Re: [PATCH kernel v5 10/10] KVM: PPC: VFIO: Add in-kernel acceleration for VFIO

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On 24/02/17 14:43, Alexey Kardashevskiy wrote:
> On 24/02/17 14:36, David Gibson wrote:
>> On Fri, Feb 24, 2017 at 02:29:14PM +1100, Alexey Kardashevskiy wrote:
>>> On 24/02/17 13:14, David Gibson wrote:
>>>> On Wed, Feb 22, 2017 at 07:21:33PM +1100, Alexey Kardashevskiy wrote:
>>>>> This allows the host kernel to handle H_PUT_TCE, H_PUT_TCE_INDIRECT
>>>>> and H_STUFF_TCE requests targeted an IOMMU TCE table used for VFIO
>>>>> without passing them to user space which saves time on switching
>>>>> to user space and back.
>>>>>
>>>>> This adds H_PUT_TCE/H_PUT_TCE_INDIRECT/H_STUFF_TCE handlers to KVM.
>>>>> KVM tries to handle a TCE request in the real mode, if failed
>>>>> it passes the request to the virtual mode to complete the operation.
>>>>> If it a virtual mode handler fails, the request is passed to
>>>>> the user space; this is not expected to happen though.
>>>>>
>>>>> To avoid dealing with page use counters (which is tricky in real mode),
>>>>> this only accelerates SPAPR TCE IOMMU v2 clients which are required
>>>>> to pre-register the userspace memory. The very first TCE request will
>>>>> be handled in the VFIO SPAPR TCE driver anyway as the userspace view
>>>>> of the TCE table (iommu_table::it_userspace) is not allocated till
>>>>> the very first mapping happens and we cannot call vmalloc in real mode.
>>>>>
>>>>> If we fail to update a hardware IOMMU table unexpected reason, we just
>>>>> clear it and move on as there is nothing really we can do about it -
>>>>> for example, if we hot plug a VFIO device to a guest, existing TCE tables
>>>>> will be mirrored automatically to the hardware and there is no interface
>>>>> to report to the guest about possible failures.
>>>>>
>>>>> This adds new attribute - KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE - to
>>>>> the VFIO KVM device. It takes a VFIO group fd and SPAPR TCE table fd
>>>>> and associates a physical IOMMU table with the SPAPR TCE table (which
>>>>> is a guest view of the hardware IOMMU table). The iommu_table object
>>>>> is cached and referenced so we do not have to look up for it in real mode.
>>>>>
>>>>> This does not implement the UNSET counterpart as there is no use for it -
>>>>> once the acceleration is enabled, the existing userspace won't
>>>>> disable it unless a VFIO container is destroyed; this adds necessary
>>>>> cleanup to the KVM_DEV_VFIO_GROUP_DEL handler.
>>>>>
>>>>> As this creates a descriptor per IOMMU table-LIOBN couple (called
>>>>> kvmppc_spapr_tce_iommu_table), it is possible to have several
>>>>> descriptors with the same iommu_table (hardware IOMMU table) attached
>>>>> to the same LIOBN; we do not remove duplicates though as
>>>>> iommu_table_ops::exchange not just update a TCE entry (which is
>>>>> shared among IOMMU groups) but also invalidates the TCE cache
>>>>> (one per IOMMU group).
>>>>>
>>>>> This advertises the new KVM_CAP_SPAPR_TCE_VFIO capability to the user
>>>>> space.
>>>>>
>>>>> This finally makes use of vfio_external_user_iommu_id() which was
>>>>> introduced quite some time ago and was considered for removal.
>>>>>
>>>>> Tests show that this patch increases transmission speed from 220MB/s
>>>>> to 750..1020MB/s on 10Gb network (Chelsea CXGB3 10Gb ethernet card).
>>>>>
>>>>> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
>>>>
>>>> I have some comments on this patch, but all the definite ones are
>>>> pretty minor and could be done as later cleanups.
>>>>
>>>> I have some more serious queries, but they are just queries and
>>>> requests for clarification.  If there are satisfactory answers to
>>>> them, I'll add my R-b.
>>>>
>>>>
>>>> ---
>>>>> Changes:
>>>>> v5:
>>>>> * changed error codes in multiple places
>>>>> * added bunch of WARN_ON() in places which should not really happen
>>>>> * adde a check that an iommu table is not attached already to LIOBN
>>>>> * dropped explicit calls to iommu_tce_clear_param_check/
>>>>> iommu_tce_put_param_check as kvmppc_tce_validate/kvmppc_ioba_validate
>>>>> call them anyway (since the previous patch)
>>>>> * if we fail to update a hardware IOMMU table for unexpected reason,
>>>>> this just clears the entry
>>>>>
>>>>> v4:
>>>>> * added note to the commit log about allowing multiple updates of
>>>>> the same IOMMU table;
>>>>> * instead of checking for if any memory was preregistered, this
>>>>> returns H_TOO_HARD if a specific page was not;
>>>>> * fixed comments from v3 about error handling in many places;
>>>>> * simplified TCE handlers and merged IOMMU parts inline - for example,
>>>>> there used to be kvmppc_h_put_tce_iommu(), now it is merged into
>>>>> kvmppc_h_put_tce(); this allows to check IOBA boundaries against
>>>>> the first attached table only (makes the code simpler);
>>>>>
>>>>> v3:
>>>>> * simplified not to use VFIO group notifiers
>>>>> * reworked cleanup, should be cleaner/simpler now
>>>>>
>>>>> v2:
>>>>> * reworked to use new VFIO notifiers
>>>>> * now same iommu_table may appear in the list several times, to be fixed later
>>>>> ---
>>>>>  Documentation/virtual/kvm/devices/vfio.txt |  22 ++-
>>>>>  arch/powerpc/include/asm/kvm_host.h        |   8 +
>>>>>  arch/powerpc/include/asm/kvm_ppc.h         |   4 +
>>>>>  include/uapi/linux/kvm.h                   |   8 +
>>>>>  arch/powerpc/kvm/book3s_64_vio.c           | 307 ++++++++++++++++++++++++++++-
>>>>>  arch/powerpc/kvm/book3s_64_vio_hv.c        | 152 +++++++++++++-
>>>>>  arch/powerpc/kvm/powerpc.c                 |   2 +
>>>>>  virt/kvm/vfio.c                            |  60 ++++++
>>>>>  8 files changed, 555 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt
>>>>> index ef51740c67ca..f95d867168ea 100644
>>>>> --- a/Documentation/virtual/kvm/devices/vfio.txt
>>>>> +++ b/Documentation/virtual/kvm/devices/vfio.txt
>>>>> @@ -16,7 +16,25 @@ Groups:
>>>>>  
>>>>>  KVM_DEV_VFIO_GROUP attributes:
>>>>>    KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking
>>>>> +	kvm_device_attr.addr points to an int32_t file descriptor
>>>>> +	for the VFIO group.
>>>>>    KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking
>>>>> +	kvm_device_attr.addr points to an int32_t file descriptor
>>>>> +	for the VFIO group.
>>>>> +  KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
>>>>> +	allocated by sPAPR KVM.
>>>>> +	kvm_device_attr.addr points to a struct:
>>>>>  
>>>>> -For each, kvm_device_attr.addr points to an int32_t file descriptor
>>>>> -for the VFIO group.
>>>>> +	struct kvm_vfio_spapr_tce {
>>>>> +		__u32	argsz;
>>>>> +		__u32	flags;
>>>>> +		__s32	groupfd;
>>>>> +		__s32	tablefd;
>>>>> +	};
>>>>> +
>>>>> +	where
>>>>> +	@argsz is the size of kvm_vfio_spapr_tce_liobn;
>>>>> +	@flags are not supported now, must be zero;
>>>>> +	@groupfd is a file descriptor for a VFIO group;
>>>>> +	@tablefd is a file descriptor for a TCE table allocated via
>>>>> +		KVM_CREATE_SPAPR_TCE.
>>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
>>>>> index e59b172666cd..a827006941f8 100644
>>>>> --- a/arch/powerpc/include/asm/kvm_host.h
>>>>> +++ b/arch/powerpc/include/asm/kvm_host.h
>>>>> @@ -191,6 +191,13 @@ struct kvmppc_pginfo {
>>>>>  	atomic_t refcnt;
>>>>>  };
>>>>>  
>>>>> +struct kvmppc_spapr_tce_iommu_table {
>>>>> +	struct rcu_head rcu;
>>>>> +	struct list_head next;
>>>>> +	struct vfio_group *group;
>>>>> +	struct iommu_table *tbl;
>>>>> +};
>>>>> +
>>>>>  struct kvmppc_spapr_tce_table {
>>>>>  	struct list_head list;
>>>>>  	struct kvm *kvm;
>>>>> @@ -199,6 +206,7 @@ struct kvmppc_spapr_tce_table {
>>>>>  	u32 page_shift;
>>>>>  	u64 offset;		/* in pages */
>>>>>  	u64 size;		/* window size in pages */
>>>>> +	struct list_head iommu_tables;
>>>>>  	struct page *pages[0];
>>>>>  };
>>>>>  
>>>>> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
>>>>> index e04b7fb8ccaa..b8a39dec92cf 100644
>>>>> --- a/arch/powerpc/include/asm/kvm_ppc.h
>>>>> +++ b/arch/powerpc/include/asm/kvm_ppc.h
>>>>> @@ -163,6 +163,10 @@ extern long kvmppc_prepare_vrma(struct kvm *kvm,
>>>>>  extern void kvmppc_map_vrma(struct kvm_vcpu *vcpu,
>>>>>  			struct kvm_memory_slot *memslot, unsigned long porder);
>>>>>  extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
>>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd,
>>>>> +		struct vfio_group *group);
>>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
>>>>> +		struct vfio_group *group);
>>>>>  
>>>>>  extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>>>>  				struct kvm_create_spapr_tce_64 *args);
>>>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>>>> index a2c9bb5a0ead..cdfa01169bd2 100644
>>>>> --- a/include/uapi/linux/kvm.h
>>>>> +++ b/include/uapi/linux/kvm.h
>>>>> @@ -1076,6 +1076,7 @@ struct kvm_device_attr {
>>>>>  #define  KVM_DEV_VFIO_GROUP			1
>>>>>  #define   KVM_DEV_VFIO_GROUP_ADD			1
>>>>>  #define   KVM_DEV_VFIO_GROUP_DEL			2
>>>>> +#define   KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE		3
>>>>>  
>>>>>  enum kvm_device_type {
>>>>>  	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
>>>>> @@ -1097,6 +1098,13 @@ enum kvm_device_type {
>>>>>  	KVM_DEV_TYPE_MAX,
>>>>>  };
>>>>>  
>>>>> +struct kvm_vfio_spapr_tce {
>>>>> +	__u32	argsz;
>>>>> +	__u32	flags;
>>>>> +	__s32	groupfd;
>>>>> +	__s32	tablefd;
>>>>> +};
>>>>> +
>>>>>  /*
>>>>>   * ioctls for VM fds
>>>>>   */
>>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
>>>>> index 15df8ae627d9..062407af09ee 100644
>>>>> --- a/arch/powerpc/kvm/book3s_64_vio.c
>>>>> +++ b/arch/powerpc/kvm/book3s_64_vio.c
>>>>> @@ -27,6 +27,10 @@
>>>>>  #include <linux/hugetlb.h>
>>>>>  #include <linux/list.h>
>>>>>  #include <linux/anon_inodes.h>
>>>>> +#include <linux/iommu.h>
>>>>> +#include <linux/file.h>
>>>>> +#include <linux/vfio.h>
>>>>> +#include <linux/module.h>
>>>>>  
>>>>>  #include <asm/tlbflush.h>
>>>>>  #include <asm/kvm_ppc.h>
>>>>> @@ -39,6 +43,36 @@
>>>>>  #include <asm/udbg.h>
>>>>>  #include <asm/iommu.h>
>>>>>  #include <asm/tce.h>
>>>>> +#include <asm/mmu_context.h>
>>>>> +
>>>>> +static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
>>>>> +{
>>>>> +	void (*fn)(struct vfio_group *);
>>>>> +
>>>>> +	fn = symbol_get(vfio_group_put_external_user);
>>>>> +	if (WARN_ON(!fn))
>>>>> +		return;
>>>>> +
>>>>> +	fn(vfio_group);
>>>>> +
>>>>> +	symbol_put(vfio_group_put_external_user);
>>>>> +}
>>>>> +
>>>>> +static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group)
>>>>> +{
>>>>> +	int (*fn)(struct vfio_group *);
>>>>> +	int ret = -1;
>>>>> +
>>>>> +	fn = symbol_get(vfio_external_user_iommu_id);
>>>>> +	if (!fn)
>>>>> +		return ret;
>>>>> +
>>>>> +	ret = fn(vfio_group);
>>>>> +
>>>>> +	symbol_put(vfio_external_user_iommu_id);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>>  
>>>>>  static unsigned long kvmppc_tce_pages(unsigned long iommu_pages)
>>>>>  {
>>>>> @@ -90,6 +124,130 @@ static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc)
>>>>>  	return ret;
>>>>>  }
>>>>>  
>>>>> +static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit = container_of(head,
>>>>> +			struct kvmppc_spapr_tce_iommu_table, rcu);
>>>>> +
>>>>> +	iommu_table_put(stit->tbl);
>>>>> +	kvm_vfio_group_put_external_user(stit->group);
>>>>> +
>>>>> +	kfree(stit);
>>>>> +}
>>>>> +
>>>>> +static void kvm_spapr_tce_liobn_release_iommu_group(
>>>>> +		struct kvmppc_spapr_tce_table *stt,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit, *tmp;
>>>>> +
>>>>> +	list_for_each_entry_safe(stit, tmp, &stt->iommu_tables, next) {
>>>>> +		if (group && (stit->group != group))
>>>>> +			continue;
>>>>> +
>>>>> +		list_del_rcu(&stit->next);
>>>>> +
>>>>> +		call_rcu(&stit->rcu, kvm_spapr_tce_iommu_table_free);
>>>>> +	}
>>>>> +}
>>>>> +
>>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_table *stt;
>>>>> +
>>>>> +	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list)
>>>>> +		kvm_spapr_tce_liobn_release_iommu_group(stt, group);
>>>>> +}
>>>>> +
>>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_table *stt = NULL;
>>>>> +	bool found = false;
>>>>> +	struct iommu_table *tbl = NULL;
>>>>> +	struct iommu_table_group *table_group;
>>>>> +	long i, ret = 0;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	struct fd f;
>>>>> +	int group_id;
>>>>> +	struct iommu_group *grp;
>>>>> +
>>>>> +	group_id = kvm_vfio_external_user_iommu_id(group);
>>>>> +	grp = iommu_group_get_by_id(group_id);
>>>>> +	if (WARN_ON(!grp))
>>>>> +		return -EIO;
>>>>
>>>> I think it would be nicer to have a function that goes directly from
>>>> vfio_group to iommu_group rather than going via id.  That can be a
>>>> later cleanup, though.
>>>>
>>>>> +
>>>>> +	f = fdget(tablefd);
>>>>> +	if (!f.file) {
>>>>> +		ret = -EBADF;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
>>>>> +		if (stt == f.file->private_data) {
>>>>> +			found = true;
>>>>> +			break;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	fdput(f);
>>>>> +
>>>>> +	if (!found) {
>>>>> +		ret = -EINVAL;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	table_group = iommu_group_get_iommudata(grp);
>>>>> +	if (WARN_ON(!table_group)) {
>>>>> +		ret = -EFAULT;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>>>>> +		struct iommu_table *tbltmp = table_group->tables[i];
>>>>> +
>>>>> +		if (!tbltmp)
>>>>> +			continue;
>>>>> +
>>>>> +		/*
>>>>> +		 * Make sure hardware table parameters are exactly the same;
>>>>> +		 * this is used in the TCE handlers where boundary checks
>>>>> +		 * use only the first attached table.
>>>>> +		 */
>>>>> +		if ((tbltmp->it_page_shift == stt->page_shift) &&
>>>>> +				(tbltmp->it_offset == stt->offset) &&
>>>>> +				(tbltmp->it_size == stt->size)) {
>>>>> +			tbl = tbltmp;
>>>>> +			break;
>>>>> +		}
>>>>> +	}
>>>>> +	if (!tbl) {
>>>>> +		ret = -EINVAL;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	list_for_each_entry_rcu(stit, &stt->iommu_tables, next) {
>>>>> +		if ((stit->tbl == tbl) && (stit->group == group)) {
>>>>> +			ret = -EBUSY;
>>>>> +			goto put_exit;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	iommu_table_get(tbl);
>>>>> +
>>>>> +	stit = kzalloc(sizeof(*stit), GFP_KERNEL);
>>>>> +	stit->tbl = tbl;
>>>>> +	stit->group = group;
>>>>> +
>>>>> +	list_add_rcu(&stit->next, &stt->iommu_tables);
>>>>> +
>>>>> +put_exit:
>>>>> +	iommu_group_put(grp);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>>  static void release_spapr_tce_table(struct rcu_head *head)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt = container_of(head,
>>>>> @@ -132,6 +290,8 @@ static int kvm_spapr_tce_release(struct inode *inode, struct file *filp)
>>>>>  
>>>>>  	list_del_rcu(&stt->list);
>>>>>  
>>>>> +	kvm_spapr_tce_liobn_release_iommu_group(stt, NULL /* release all */);
>>>>> +
>>>>>  	kvm_put_kvm(stt->kvm);
>>>>>  
>>>>>  	kvmppc_account_memlimit(
>>>>> @@ -181,6 +341,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>>>>  	stt->offset = args->offset;
>>>>>  	stt->size = size;
>>>>>  	stt->kvm = kvm;
>>>>> +	INIT_LIST_HEAD_RCU(&stt->iommu_tables);
>>>>>  
>>>>>  	for (i = 0; i < npages; i++) {
>>>>>  		stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
>>>>> @@ -209,11 +370,102 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>>>>  	return ret;
>>>>>  }
>>>>>  
>>>>> +static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	unsigned long hpa = 0;
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +
>>>>> +	iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	struct mm_iommu_table_group_mem_t *mem = NULL;
>>>>
>>>> Initialization is unnecessary for the variable above.
>>>>
>>>>> +	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	mem = mm_iommu_lookup(kvm->mm, *pua, pgsize);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mm_iommu_mapped_dec(mem);
>>>>> +
>>>>> +	*pua = 0;
>>>>> +
>>>>> +	return H_SUCCESS;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_tce_iommu_unmap(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +	unsigned long hpa = 0;
>>>>> +	long ret;
>>>>> +
>>>>> +	if (iommu_tce_xchg(tbl, entry, &hpa, &dir))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	if (dir == DMA_NONE)
>>>>> +		return H_SUCCESS;
>>>>> +
>>>>> +	ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +	if (ret != H_SUCCESS)
>>>>> +		iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +long kvmppc_tce_iommu_map(struct kvm *kvm, struct iommu_table *tbl,
>>>>> +		unsigned long entry, unsigned long gpa,
>>>>> +		enum dma_data_direction dir)
>>>>> +{
>>>>> +	long ret;
>>>>> +	unsigned long hpa, ua, *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +	struct mm_iommu_table_group_mem_t *mem;
>>>>> +
>>>>> +	if (!pua)
>>>>> +		/* it_userspace allocation might be delayed */
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>>>>> +		return H_PARAMETER;
>>>>> +
>>>>> +	mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_ua_to_hpa(mem, ua, &hpa)))
>>>>> +		return H_HARDWARE;
>>>>
>>>> Remind me - could a failure here be triggered by userspace failing to
>>>> preregister all the memory it should?
>>>
>>>
>>> mm_iommu_lookup() should fail first as the only reason for
>>> mm_iommu_ua_to_hpa() to fail is (entry >= mem->entries) but this is checked
>>> in mm_iommu_lookup().
>>
>> Ah, yes of course, I forgot.  Ok, that should be fine.
>>
>>
>>>>
>>>>> +	if (mm_iommu_mapped_inc(mem))
>>>>> +		return H_CLOSED;
>>>>> +
>>>>> +	ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +	if (ret) {
>>>>> +		mm_iommu_mapped_dec(mem);
>>>>> +		return H_TOO_HARD;
>>>>> +	}
>>>>> +
>>>>> +	if (dir != DMA_NONE)
>>>>> +		kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +
>>>>> +	*pua = ua;
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  		      unsigned long ioba, unsigned long tce)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>> -	long ret;
>>>>> +	long ret, idx;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	unsigned long entry, gpa;
>>>>> +	enum dma_data_direction dir;
>>>>>  
>>>>>  	/* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>>>>>  	/* 	    liobn, ioba, tce); */
>>>>> @@ -230,7 +482,28 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  	if (ret != H_SUCCESS)
>>>>>  		return ret;
>>>>>  
>>>>> -	kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>>>> +	entry = ioba >> stt->page_shift;
>>>>> +	gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +	dir = iommu_tce_direction(tce);
>>>>> +
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		if (dir == DMA_NONE) {
>>>>> +			ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry);
>>>>> +		} else {
>>>>> +			idx = srcu_read_lock(&vcpu->kvm->srcu);
>>>>> +			ret = kvmppc_tce_iommu_map(vcpu->kvm, stit->tbl,
>>>>> +					entry, gpa, dir);
>>>>> +			srcu_read_unlock(&vcpu->kvm->srcu, idx);
>>>>> +		}
>>>>> +
>>>>> +		if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +			kvmppc_clear_tce(stit->tbl, entry);
>>>>> +		else if (ret != H_SUCCESS)
>>>>> +			return ret;
>>>>> +	}
>>>>> +
>>>>> +	kvmppc_tce_put(stt, entry, tce);
>>>>>  
>>>>>  	return H_SUCCESS;
>>>>>  }
>>>>> @@ -242,9 +515,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret = H_SUCCESS, idx;
>>>>> -	unsigned long entry, ua = 0;
>>>>> +	unsigned long entry, ua = 0, gpa;
>>>>>  	u64 __user *tces;
>>>>>  	u64 tce;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>  
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -283,6 +557,18 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>>>>>  		if (ret != H_SUCCESS)
>>>>>  			goto unlock_exit;
>>>>>  
>>>>> +		gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +
>>>>> +		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +			ret = kvmppc_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry + i, gpa,
>>>>> +					iommu_tce_direction(tce));
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				goto unlock_exit;
>>>>> +		}
>>>>> +
>>>>>  		kvmppc_tce_put(stt, entry + i, tce);
>>>>>  	}
>>>>>  
>>>>> @@ -299,6 +585,7 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>  
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -312,6 +599,20 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  	if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
>>>>>  		return H_PARAMETER;
>>>>>  
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		unsigned long entry = ioba >> stit->tbl->it_page_shift;
>>>>> +
>>>>> +		for (i = 0; i < npages; ++i) {
>>>>> +			ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry + i);
>>>>> +
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				return ret;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>>  	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
>>>>>  		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);
>>>>>  
>>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> index 92d769f4eaea..4a1d978ebd98 100644
>>>>> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> @@ -161,11 +161,111 @@ long kvmppc_gpa_to_ua(struct kvm *kvm, unsigned long gpa,
>>>>>  EXPORT_SYMBOL_GPL(kvmppc_gpa_to_ua);
>>>>>  
>>>>>  #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
>>>>> +static void kvmppc_rm_clear_tce(struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	unsigned long hpa = 0;
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +
>>>>> +	iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	struct mm_iommu_table_group_mem_t *mem = NULL;
>>>>> +	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	pua = (void *) vmalloc_to_phys(pua);
>>>>> +	if (!pua)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mem = mm_iommu_lookup_rm(kvm->mm, *pua, pgsize);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mm_iommu_mapped_dec(mem);
>>>>> +
>>>>> +	*pua = 0;
>>>>> +
>>>>> +	return H_SUCCESS;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_unmap(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +	unsigned long hpa = 0;
>>>>> +	long ret;
>>>>> +
>>>>> +	if (iommu_tce_xchg_rm(tbl, entry, &hpa, &dir))
>>>>> +		return H_HARDWARE;
>>>>
>>>> To avoid a double WARN() (and to make the warnings easier to
>>>> understand) I'd suggest putting a WARN_ON() here, rather than in the
>>>> callers when they receieve an H_HARDWARE.  IIUC this really shouldn't
>>>> ever happen, and it certainly can't be the guest's fault?
>>>
>>>
>>> Makes sense.
>>
>> I guess it might want WARN_ON_ONCE() to avoid spamming the user with
>> errors for every TCE, though.
> 
> 
> We do not expect this to happen at all :) I can convert all of them to
> _ONCE really as the purpose of WARN_ON is mostly to document what we do not
> expect.
> 
> 
> 
>>>>> +
>>>>> +	if (dir == DMA_NONE)
>>>>> +		return H_SUCCESS;
>>>>> +
>>>>> +	ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +	if (ret)
>>>>> +		iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_map(struct kvm *kvm, struct iommu_table *tbl,
>>>>> +		unsigned long entry, unsigned long gpa,
>>>>> +		enum dma_data_direction dir)
>>>>> +{
>>>>> +	long ret;
>>>>> +	unsigned long hpa = 0, ua;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +	struct mm_iommu_table_group_mem_t *mem;
>>>>> +
>>>>> +	if (!pua)
>>>>> +		/* it_userspace allocation might be delayed */
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>>>>> +		return H_PARAMETER;
>>>
>>>
>>> Referred below as [1]
>>>
>>>
>>>>> +
>>>>> +	mem = mm_iommu_lookup_rm(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_ua_to_hpa_rm(mem, ua, &hpa)))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	pua = (void *) vmalloc_to_phys(pua);
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_mapped_inc(mem)))
>>>>> +		return H_CLOSED;
>>>>> +
>>>>> +	ret = iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +	if (ret) {
>>>>> +		mm_iommu_mapped_dec(mem);
>>>>> +		return H_TOO_HARD;
>>>>> +	}
>>>>> +
>>>>> +	if (dir != DMA_NONE)
>>>>> +		kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +
>>>>> +	*pua = ua;
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  		unsigned long ioba, unsigned long tce)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	unsigned long entry, gpa;
>>>>> +	enum dma_data_direction dir;
>>>>>  
>>>>>  	/* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>>>>>  	/* 	    liobn, ioba, tce); */
>>>>> @@ -182,7 +282,25 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  	if (ret != H_SUCCESS)
>>>>>  		return ret;
>>>>>  
>>>>> -	kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>>>> +	entry = ioba >> stt->page_shift;
>>>>> +	gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +	dir = iommu_tce_direction(tce);
>>>>> +
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		if (dir == DMA_NONE)
>>>>> +			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry);
>>>>> +		else
>>>>> +			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry, gpa, dir);
>>>>> +
>>>>> +		if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +			kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>> +		else if (ret != H_SUCCESS)
>>>>> +			return ret;
>>>>> +	}
>>>>> +
>>>>> +	kvmppc_tce_put(stt, entry, tce);
>>>>>  
>>>>>  	return H_SUCCESS;
>>>>>  }
>>>>> @@ -220,9 +338,10 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret = H_SUCCESS;
>>>>> -	unsigned long tces, entry, ua = 0;
>>>>> +	unsigned long tces, entry, ua = 0, tce, gpa;
>>>>>  	unsigned long *rmap = NULL;
>>>>>  	bool prereg = false;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>  
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -287,12 +406,24 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
>>>>>  	}
>>>>>  
>>>>>  	for (i = 0; i < npages; ++i) {
>>>>> -		unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
>>>>> +		tce = be64_to_cpu(((u64 *)tces)[i]);
>>>>>  
>>>>>  		ret = kvmppc_tce_validate(stt, tce);
>>>>>  		if (ret != H_SUCCESS)
>>>>>  			goto unlock_exit;
>>>>>  
>>>>> +		gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +
>>>>> +		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry + i, gpa,
>>>>> +					iommu_tce_direction(tce));
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>
>>>> I don't think you need the WARN() here - the only H_HARDWARE failure
>>>> path in iommu_map() already includes a WARN().
>>>
>>>
>>> True, I can drop it here.
>>>
>>>
>>>>
>>>>> +				kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				goto unlock_exit;
>>>>
>>>> It's also not clear to me why the H_HARDWARE error path clears the
>>>> entry, but the other failure paths don't.  Or why an H_HARDWARE will
>>>> result in continuing to set the rest of the TCEs, but other failures
>>>> won't.
>>>
>>>
>>> The idea was that other failures still have some chance that handling may
>>> succeed in virtual mode or via QEMU, H_HARDWARE is fatal.
>>
>> Um... yes.. but the logic seems to be backwards for that: on
>> H_HARDWARE you warn and keep going, on other errors you bail out
>> entirely.
> 
> By "fatal" I means fatal for this particular hardware TCE(s), no hope in
> trying this particular TCE in virtual mode.
> 
> 
>>
>>> I am just not sure if H_PARAMETER is what I want to return at [1], to make
>>> the calling code simplier, I could return H_HARDWARE there as well (instead
>>> of H_PARAMETER).
>>
>> That sounds right, IIUC the gpa to ua translation shouldn't ever
>> fail because of something the guest did. 
> 
> 
> The guest can easily pass bad TCE/GPA which is not in any registered slot.
> So it is rather H_PARAMETER.
> 
>> So I'd expect either
>> H_HARDWARE, or H_TOO_HARD (if there's some hope that virtual mode can
>> make the translation when real mode couldn't).
> 
> No, virtual mode uses the exact same helper.


I just realized that kvmppc_gpa_to_ua() could be a part of
kvmppc_tce_validate() and kvmppc_rm_tce_iommu_map() could just receive the
userspace address rather than guest physical.


> 
> 
>>>>> +		}
>>>>> +
>>>>>  		kvmppc_tce_put(stt, entry + i, tce);
>>>>>  	}
>>>>>  
>>>>> @@ -309,6 +440,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>  
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -322,6 +454,20 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  	if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
>>>>>  		return H_PARAMETER;
>>>>>  
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		unsigned long entry = ioba >> stit->tbl->it_page_shift;
>>>>> +
>>>>> +		for (i = 0; i < npages; ++i) {
>>>>> +			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry + i);
>>>>> +
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>
>>>> As noted earlier, I think this WARN belongs within iommu_unmap()
>>>> rather than out here.
>>>>
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				return ret;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>>  	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
>>>>>  		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);
>>>>>  
>>>>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>>>>> index cd892dec7cb6..f3127dc87912 100644
>>>>> --- a/arch/powerpc/kvm/powerpc.c
>>>>> +++ b/arch/powerpc/kvm/powerpc.c
>>>>> @@ -536,6 +536,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>>>>  #ifdef CONFIG_PPC_BOOK3S_64
>>>>>  	case KVM_CAP_SPAPR_TCE:
>>>>>  	case KVM_CAP_SPAPR_TCE_64:
>>>>> +		/* fallthrough */
>>>>> +	case KVM_CAP_SPAPR_TCE_VFIO:
>>>>>  	case KVM_CAP_PPC_RTAS:
>>>>>  	case KVM_CAP_PPC_FIXUP_HCALL:
>>>>>  	case KVM_CAP_PPC_ENABLE_HCALL:
>>>>> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
>>>>> index d32f239eb471..2b7dc22265fe 100644
>>>>> --- a/virt/kvm/vfio.c
>>>>> +++ b/virt/kvm/vfio.c
>>>>> @@ -20,6 +20,10 @@
>>>>>  #include <linux/vfio.h>
>>>>>  #include "vfio.h"
>>>>>  
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +#include <asm/kvm_ppc.h>
>>>>> +#endif
>>>>> +
>>>>>  struct kvm_vfio_group {
>>>>>  	struct list_head node;
>>>>>  	struct vfio_group *vfio_group;
>>>>> @@ -211,6 +215,9 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
>>>>>  
>>>>>  		mutex_unlock(&kv->lock);
>>>>>  
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		kvm_spapr_tce_release_iommu_group(dev->kvm, vfio_group);
>>>>> +#endif
>>>>>  		kvm_vfio_group_set_kvm(vfio_group, NULL);
>>>>>  
>>>>>  		kvm_vfio_group_put_external_user(vfio_group);
>>>>> @@ -218,6 +225,53 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
>>>>>  		kvm_vfio_update_coherency(dev);
>>>>>  
>>>>>  		return ret;
>>>>> +
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: {
>>>>> +		struct kvm_vfio_spapr_tce param;
>>>>> +		unsigned long minsz;
>>>>> +		struct kvm_vfio *kv = dev->private;
>>>>> +		struct vfio_group *vfio_group;
>>>>> +		struct kvm_vfio_group *kvg;
>>>>> +		struct fd f;
>>>>> +
>>>>> +		minsz = offsetofend(struct kvm_vfio_spapr_tce, tablefd);
>>>>> +
>>>>> +		if (copy_from_user(&param, (void __user *)arg, minsz))
>>>>> +			return -EFAULT;
>>>>> +
>>>>> +		if (param.argsz < minsz || param.flags)
>>>>> +			return -EINVAL;
>>>>> +
>>>>> +		f = fdget(param.groupfd);
>>>>> +		if (!f.file)
>>>>> +			return -EBADF;
>>>>> +
>>>>> +		vfio_group = kvm_vfio_group_get_external_user(f.file);
>>>>> +		fdput(f);
>>>>> +
>>>>> +		if (IS_ERR(vfio_group))
>>>>> +			return PTR_ERR(vfio_group);
>>>>> +
>>>>> +		ret = -ENOENT;
>>>>> +
>>>>> +		mutex_lock(&kv->lock);
>>>>> +
>>>>> +		list_for_each_entry(kvg, &kv->group_list, node) {
>>>>> +			if (kvg->vfio_group != vfio_group)
>>>>> +				continue;
>>>>> +
>>>>> +			ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
>>>>> +					param.tablefd, vfio_group);
>>>>> +
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +		mutex_unlock(&kv->lock);
>>>>> +
>>>>> +		return ret;
>>>>> +	}
>>>>> +#endif /* CONFIG_SPAPR_TCE_IOMMU */
>>>>>  	}
>>>>>  
>>>>>  	return -ENXIO;
>>>>> @@ -242,6 +296,9 @@ static int kvm_vfio_has_attr(struct kvm_device *dev,
>>>>>  		switch (attr->attr) {
>>>>>  		case KVM_DEV_VFIO_GROUP_ADD:
>>>>>  		case KVM_DEV_VFIO_GROUP_DEL:
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
>>>>> +#endif
>>>>>  			return 0;
>>>>>  		}
>>>>>  
>>>>> @@ -257,6 +314,9 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
>>>>>  	struct kvm_vfio_group *kvg, *tmp;
>>>>>  
>>>>>  	list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		kvm_spapr_tce_release_iommu_group(dev->kvm, kvg->vfio_group);
>>>>> +#endif
>>>>>  		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
>>>>>  		kvm_vfio_group_put_external_user(kvg->vfio_group);
>>>>>  		list_del(&kvg->node);
>>>>
>>>
>>>
>>
>>
>>
>>
> 
> 


-- 
Alexey
On 24/02/17 14:43, Alexey Kardashevskiy wrote:
> On 24/02/17 14:36, David Gibson wrote:
>> On Fri, Feb 24, 2017 at 02:29:14PM +1100, Alexey Kardashevskiy wrote:
>>> On 24/02/17 13:14, David Gibson wrote:
>>>> On Wed, Feb 22, 2017 at 07:21:33PM +1100, Alexey Kardashevskiy wrote:
>>>>> This allows the host kernel to handle H_PUT_TCE, H_PUT_TCE_INDIRECT
>>>>> and H_STUFF_TCE requests targeted an IOMMU TCE table used for VFIO
>>>>> without passing them to user space which saves time on switching
>>>>> to user space and back.
>>>>>
>>>>> This adds H_PUT_TCE/H_PUT_TCE_INDIRECT/H_STUFF_TCE handlers to KVM.
>>>>> KVM tries to handle a TCE request in the real mode, if failed
>>>>> it passes the request to the virtual mode to complete the operation.
>>>>> If it a virtual mode handler fails, the request is passed to
>>>>> the user space; this is not expected to happen though.
>>>>>
>>>>> To avoid dealing with page use counters (which is tricky in real mode),
>>>>> this only accelerates SPAPR TCE IOMMU v2 clients which are required
>>>>> to pre-register the userspace memory. The very first TCE request will
>>>>> be handled in the VFIO SPAPR TCE driver anyway as the userspace view
>>>>> of the TCE table (iommu_table::it_userspace) is not allocated till
>>>>> the very first mapping happens and we cannot call vmalloc in real mode.
>>>>>
>>>>> If we fail to update a hardware IOMMU table unexpected reason, we just
>>>>> clear it and move on as there is nothing really we can do about it -
>>>>> for example, if we hot plug a VFIO device to a guest, existing TCE tables
>>>>> will be mirrored automatically to the hardware and there is no interface
>>>>> to report to the guest about possible failures.
>>>>>
>>>>> This adds new attribute - KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE - to
>>>>> the VFIO KVM device. It takes a VFIO group fd and SPAPR TCE table fd
>>>>> and associates a physical IOMMU table with the SPAPR TCE table (which
>>>>> is a guest view of the hardware IOMMU table). The iommu_table object
>>>>> is cached and referenced so we do not have to look up for it in real
mode.
>>>>>
>>>>> This does not implement the UNSET counterpart as there is no use for it -
>>>>> once the acceleration is enabled, the existing userspace won't
>>>>> disable it unless a VFIO container is destroyed; this adds necessary
>>>>> cleanup to the KVM_DEV_VFIO_GROUP_DEL handler.
>>>>>
>>>>> As this creates a descriptor per IOMMU table-LIOBN couple (called
>>>>> kvmppc_spapr_tce_iommu_table), it is possible to have several
>>>>> descriptors with the same iommu_table (hardware IOMMU table) attached
>>>>> to the same LIOBN; we do not remove duplicates though as
>>>>> iommu_table_ops::exchange not just update a TCE entry (which is
>>>>> shared among IOMMU groups) but also invalidates the TCE cache
>>>>> (one per IOMMU group).
>>>>>
>>>>> This advertises the new KVM_CAP_SPAPR_TCE_VFIO capability to the user
>>>>> space.
>>>>>
>>>>> This finally makes use of vfio_external_user_iommu_id() which was
>>>>> introduced quite some time ago and was considered for removal.
>>>>>
>>>>> Tests show that this patch increases transmission speed from 220MB/s
>>>>> to 750..1020MB/s on 10Gb network (Chelsea CXGB3 10Gb ethernet card).
>>>>>
>>>>> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
>>>>
>>>> I have some comments on this patch, but all the definite ones are
>>>> pretty minor and could be done as later cleanups.
>>>>
>>>> I have some more serious queries, but they are just queries and
>>>> requests for clarification.  If there are satisfactory answers to
>>>> them, I'll add my R-b.
>>>>
>>>>
>>>> ---
>>>>> Changes:
>>>>> v5:
>>>>> * changed error codes in multiple places
>>>>> * added bunch of WARN_ON() in places which should not really happen
>>>>> * adde a check that an iommu table is not attached already to LIOBN
>>>>> * dropped explicit calls to iommu_tce_clear_param_check/
>>>>> iommu_tce_put_param_check as kvmppc_tce_validate/kvmppc_ioba_validate
>>>>> call them anyway (since the previous patch)
>>>>> * if we fail to update a hardware IOMMU table for unexpected reason,
>>>>> this just clears the entry
>>>>>
>>>>> v4:
>>>>> * added note to the commit log about allowing multiple updates of
>>>>> the same IOMMU table;
>>>>> * instead of checking for if any memory was preregistered, this
>>>>> returns H_TOO_HARD if a specific page was not;
>>>>> * fixed comments from v3 about error handling in many places;
>>>>> * simplified TCE handlers and merged IOMMU parts inline - for example,
>>>>> there used to be kvmppc_h_put_tce_iommu(), now it is merged into
>>>>> kvmppc_h_put_tce(); this allows to check IOBA boundaries against
>>>>> the first attached table only (makes the code simpler);
>>>>>
>>>>> v3:
>>>>> * simplified not to use VFIO group notifiers
>>>>> * reworked cleanup, should be cleaner/simpler now
>>>>>
>>>>> v2:
>>>>> * reworked to use new VFIO notifiers
>>>>> * now same iommu_table may appear in the list several times, to be
fixed later
>>>>> ---
>>>>>  Documentation/virtual/kvm/devices/vfio.txt |  22 ++-
>>>>>  arch/powerpc/include/asm/kvm_host.h        |   8 +
>>>>>  arch/powerpc/include/asm/kvm_ppc.h         |   4 +
>>>>>  include/uapi/linux/kvm.h                   |   8 +
>>>>>  arch/powerpc/kvm/book3s_64_vio.c           | 307
++++++++++++++++++++++++++++-
>>>>>  arch/powerpc/kvm/book3s_64_vio_hv.c        | 152 +++++++++++++-
>>>>>  arch/powerpc/kvm/powerpc.c                 |   2 +
>>>>>  virt/kvm/vfio.c                            |  60 ++++++
>>>>>  8 files changed, 555 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/Documentation/virtual/kvm/devices/vfio.txt
b/Documentation/virtual/kvm/devices/vfio.txt
>>>>> index ef51740c67ca..f95d867168ea 100644
>>>>> --- a/Documentation/virtual/kvm/devices/vfio.txt
>>>>> +++ b/Documentation/virtual/kvm/devices/vfio.txt
>>>>> @@ -16,7 +16,25 @@ Groups:
>>>>>
>>>>>  KVM_DEV_VFIO_GROUP attributes:
>>>>>    KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking
>>>>> +	kvm_device_attr.addr points to an int32_t file descriptor
>>>>> +	for the VFIO group.
>>>>>    KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device
tracking
>>>>> +	kvm_device_attr.addr points to an int32_t file descriptor
>>>>> +	for the VFIO group.
>>>>> +  KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
>>>>> +	allocated by sPAPR KVM.
>>>>> +	kvm_device_attr.addr points to a struct:
>>>>>
>>>>> -For each, kvm_device_attr.addr points to an int32_t file descriptor
>>>>> -for the VFIO group.
>>>>> +	struct kvm_vfio_spapr_tce {
>>>>> +		__u32	argsz;
>>>>> +		__u32	flags;
>>>>> +		__s32	groupfd;
>>>>> +		__s32	tablefd;
>>>>> +	};
>>>>> +
>>>>> +	where
>>>>> +	@argsz is the size of kvm_vfio_spapr_tce_liobn;
>>>>> +	@flags are not supported now, must be zero;
>>>>> +	@groupfd is a file descriptor for a VFIO group;
>>>>> +	@tablefd is a file descriptor for a TCE table allocated via
>>>>> +		KVM_CREATE_SPAPR_TCE.
>>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h
b/arch/powerpc/include/asm/kvm_host.h
>>>>> index e59b172666cd..a827006941f8 100644
>>>>> --- a/arch/powerpc/include/asm/kvm_host.h
>>>>> +++ b/arch/powerpc/include/asm/kvm_host.h
>>>>> @@ -191,6 +191,13 @@ struct kvmppc_pginfo {
>>>>>  	atomic_t refcnt;
>>>>>  };
>>>>>
>>>>> +struct kvmppc_spapr_tce_iommu_table {
>>>>> +	struct rcu_head rcu;
>>>>> +	struct list_head next;
>>>>> +	struct vfio_group *group;
>>>>> +	struct iommu_table *tbl;
>>>>> +};
>>>>> +
>>>>>  struct kvmppc_spapr_tce_table {
>>>>>  	struct list_head list;
>>>>>  	struct kvm *kvm;
>>>>> @@ -199,6 +206,7 @@ struct kvmppc_spapr_tce_table {
>>>>>  	u32 page_shift;
>>>>>  	u64 offset;		/* in pages */
>>>>>  	u64 size;		/* window size in pages */
>>>>> +	struct list_head iommu_tables;
>>>>>  	struct page *pages[0];
>>>>>  };
>>>>>
>>>>> diff --git a/arch/powerpc/include/asm/kvm_ppc.h
b/arch/powerpc/include/asm/kvm_ppc.h
>>>>> index e04b7fb8ccaa..b8a39dec92cf 100644
>>>>> --- a/arch/powerpc/include/asm/kvm_ppc.h
>>>>> +++ b/arch/powerpc/include/asm/kvm_ppc.h
>>>>> @@ -163,6 +163,10 @@ extern long kvmppc_prepare_vrma(struct kvm *kvm,
>>>>>  extern void kvmppc_map_vrma(struct kvm_vcpu *vcpu,
>>>>>  			struct kvm_memory_slot *memslot, unsigned long porder);
>>>>>  extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
>>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int
tablefd,
>>>>> +		struct vfio_group *group);
>>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
>>>>> +		struct vfio_group *group);
>>>>>
>>>>>  extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>>>>  				struct kvm_create_spapr_tce_64 *args);
>>>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>>>> index a2c9bb5a0ead..cdfa01169bd2 100644
>>>>> --- a/include/uapi/linux/kvm.h
>>>>> +++ b/include/uapi/linux/kvm.h
>>>>> @@ -1076,6 +1076,7 @@ struct kvm_device_attr {
>>>>>  #define  KVM_DEV_VFIO_GROUP			1
>>>>>  #define   KVM_DEV_VFIO_GROUP_ADD			1
>>>>>  #define   KVM_DEV_VFIO_GROUP_DEL			2
>>>>> +#define   KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE		3
>>>>>
>>>>>  enum kvm_device_type {
>>>>>  	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
>>>>> @@ -1097,6 +1098,13 @@ enum kvm_device_type {
>>>>>  	KVM_DEV_TYPE_MAX,
>>>>>  };
>>>>>
>>>>> +struct kvm_vfio_spapr_tce {
>>>>> +	__u32	argsz;
>>>>> +	__u32	flags;
>>>>> +	__s32	groupfd;
>>>>> +	__s32	tablefd;
>>>>> +};
>>>>> +
>>>>>  /*
>>>>>   * ioctls for VM fds
>>>>>   */
>>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio.c
b/arch/powerpc/kvm/book3s_64_vio.c
>>>>> index 15df8ae627d9..062407af09ee 100644
>>>>> --- a/arch/powerpc/kvm/book3s_64_vio.c
>>>>> +++ b/arch/powerpc/kvm/book3s_64_vio.c
>>>>> @@ -27,6 +27,10 @@
>>>>>  #include <linux/hugetlb.h>
>>>>>  #include <linux/list.h>
>>>>>  #include <linux/anon_inodes.h>
>>>>> +#include <linux/iommu.h>
>>>>> +#include <linux/file.h>
>>>>> +#include <linux/vfio.h>
>>>>> +#include <linux/module.h>
>>>>>
>>>>>  #include <asm/tlbflush.h>
>>>>>  #include <asm/kvm_ppc.h>
>>>>> @@ -39,6 +43,36 @@
>>>>>  #include <asm/udbg.h>
>>>>>  #include <asm/iommu.h>
>>>>>  #include <asm/tce.h>
>>>>> +#include <asm/mmu_context.h>
>>>>> +
>>>>> +static void kvm_vfio_group_put_external_user(struct vfio_group
*vfio_group)
>>>>> +{
>>>>> +	void (*fn)(struct vfio_group *);
>>>>> +
>>>>> +	fn = symbol_get(vfio_group_put_external_user);
>>>>> +	if (WARN_ON(!fn))
>>>>> +		return;
>>>>> +
>>>>> +	fn(vfio_group);
>>>>> +
>>>>> +	symbol_put(vfio_group_put_external_user);
>>>>> +}
>>>>> +
>>>>> +static int kvm_vfio_external_user_iommu_id(struct vfio_group
*vfio_group)
>>>>> +{
>>>>> +	int (*fn)(struct vfio_group *);
>>>>> +	int ret = -1;
>>>>> +
>>>>> +	fn = symbol_get(vfio_external_user_iommu_id);
>>>>> +	if (!fn)
>>>>> +		return ret;
>>>>> +
>>>>> +	ret = fn(vfio_group);
>>>>> +
>>>>> +	symbol_put(vfio_external_user_iommu_id);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>>
>>>>>  static unsigned long kvmppc_tce_pages(unsigned long iommu_pages)
>>>>>  {
>>>>> @@ -90,6 +124,130 @@ static long kvmppc_account_memlimit(unsigned
long stt_pages, bool inc)
>>>>>  	return ret;
>>>>>  }
>>>>>
>>>>> +static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit = container_of(head,
>>>>> +			struct kvmppc_spapr_tce_iommu_table, rcu);
>>>>> +
>>>>> +	iommu_table_put(stit->tbl);
>>>>> +	kvm_vfio_group_put_external_user(stit->group);
>>>>> +
>>>>> +	kfree(stit);
>>>>> +}
>>>>> +
>>>>> +static void kvm_spapr_tce_liobn_release_iommu_group(
>>>>> +		struct kvmppc_spapr_tce_table *stt,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit, *tmp;
>>>>> +
>>>>> +	list_for_each_entry_safe(stit, tmp, &stt->iommu_tables, next) {
>>>>> +		if (group && (stit->group != group))
>>>>> +			continue;
>>>>> +
>>>>> +		list_del_rcu(&stit->next);
>>>>> +
>>>>> +		call_rcu(&stit->rcu, kvm_spapr_tce_iommu_table_free);
>>>>> +	}
>>>>> +}
>>>>> +
>>>>> +extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_table *stt;
>>>>> +
>>>>> +	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list)
>>>>> +		kvm_spapr_tce_liobn_release_iommu_group(stt, group);
>>>>> +}
>>>>> +
>>>>> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int
tablefd,
>>>>> +		struct vfio_group *group)
>>>>> +{
>>>>> +	struct kvmppc_spapr_tce_table *stt = NULL;
>>>>> +	bool found = false;
>>>>> +	struct iommu_table *tbl = NULL;
>>>>> +	struct iommu_table_group *table_group;
>>>>> +	long i, ret = 0;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	struct fd f;
>>>>> +	int group_id;
>>>>> +	struct iommu_group *grp;
>>>>> +
>>>>> +	group_id = kvm_vfio_external_user_iommu_id(group);
>>>>> +	grp = iommu_group_get_by_id(group_id);
>>>>> +	if (WARN_ON(!grp))
>>>>> +		return -EIO;
>>>>
>>>> I think it would be nicer to have a function that goes directly from
>>>> vfio_group to iommu_group rather than going via id.  That can be a
>>>> later cleanup, though.
>>>>
>>>>> +
>>>>> +	f = fdget(tablefd);
>>>>> +	if (!f.file) {
>>>>> +		ret = -EBADF;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
>>>>> +		if (stt == f.file->private_data) {
>>>>> +			found = true;
>>>>> +			break;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	fdput(f);
>>>>> +
>>>>> +	if (!found) {
>>>>> +		ret = -EINVAL;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	table_group = iommu_group_get_iommudata(grp);
>>>>> +	if (WARN_ON(!table_group)) {
>>>>> +		ret = -EFAULT;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>>>>> +		struct iommu_table *tbltmp = table_group->tables[i];
>>>>> +
>>>>> +		if (!tbltmp)
>>>>> +			continue;
>>>>> +
>>>>> +		/*
>>>>> +		 * Make sure hardware table parameters are exactly the same;
>>>>> +		 * this is used in the TCE handlers where boundary checks
>>>>> +		 * use only the first attached table.
>>>>> +		 */
>>>>> +		if ((tbltmp->it_page_shift == stt->page_shift) &&
>>>>> +				(tbltmp->it_offset == stt->offset) &&
>>>>> +				(tbltmp->it_size == stt->size)) {
>>>>> +			tbl = tbltmp;
>>>>> +			break;
>>>>> +		}
>>>>> +	}
>>>>> +	if (!tbl) {
>>>>> +		ret = -EINVAL;
>>>>> +		goto put_exit;
>>>>> +	}
>>>>> +
>>>>> +	list_for_each_entry_rcu(stit, &stt->iommu_tables, next) {
>>>>> +		if ((stit->tbl == tbl) && (stit->group == group)) {
>>>>> +			ret = -EBUSY;
>>>>> +			goto put_exit;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	iommu_table_get(tbl);
>>>>> +
>>>>> +	stit = kzalloc(sizeof(*stit), GFP_KERNEL);
>>>>> +	stit->tbl = tbl;
>>>>> +	stit->group = group;
>>>>> +
>>>>> +	list_add_rcu(&stit->next, &stt->iommu_tables);
>>>>> +
>>>>> +put_exit:
>>>>> +	iommu_group_put(grp);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>>  static void release_spapr_tce_table(struct rcu_head *head)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt = container_of(head,
>>>>> @@ -132,6 +290,8 @@ static int kvm_spapr_tce_release(struct inode
*inode, struct file *filp)
>>>>>
>>>>>  	list_del_rcu(&stt->list);
>>>>>
>>>>> +	kvm_spapr_tce_liobn_release_iommu_group(stt, NULL /* release all */);
>>>>> +
>>>>>  	kvm_put_kvm(stt->kvm);
>>>>>
>>>>>  	kvmppc_account_memlimit(
>>>>> @@ -181,6 +341,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
>>>>>  	stt->offset = args->offset;
>>>>>  	stt->size = size;
>>>>>  	stt->kvm = kvm;
>>>>> +	INIT_LIST_HEAD_RCU(&stt->iommu_tables);
>>>>>
>>>>>  	for (i = 0; i < npages; i++) {
>>>>>  		stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
>>>>> @@ -209,11 +370,102 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm
*kvm,
>>>>>  	return ret;
>>>>>  }
>>>>>
>>>>> +static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long
entry)
>>>>> +{
>>>>> +	unsigned long hpa = 0;
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +
>>>>> +	iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	struct mm_iommu_table_group_mem_t *mem = NULL;
>>>>
>>>> Initialization is unnecessary for the variable above.
>>>>
>>>>> +	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	mem = mm_iommu_lookup(kvm->mm, *pua, pgsize);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mm_iommu_mapped_dec(mem);
>>>>> +
>>>>> +	*pua = 0;
>>>>> +
>>>>> +	return H_SUCCESS;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_tce_iommu_unmap(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +	unsigned long hpa = 0;
>>>>> +	long ret;
>>>>> +
>>>>> +	if (iommu_tce_xchg(tbl, entry, &hpa, &dir))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	if (dir == DMA_NONE)
>>>>> +		return H_SUCCESS;
>>>>> +
>>>>> +	ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +	if (ret != H_SUCCESS)
>>>>> +		iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +long kvmppc_tce_iommu_map(struct kvm *kvm, struct iommu_table *tbl,
>>>>> +		unsigned long entry, unsigned long gpa,
>>>>> +		enum dma_data_direction dir)
>>>>> +{
>>>>> +	long ret;
>>>>> +	unsigned long hpa, ua, *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +	struct mm_iommu_table_group_mem_t *mem;
>>>>> +
>>>>> +	if (!pua)
>>>>> +		/* it_userspace allocation might be delayed */
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>>>>> +		return H_PARAMETER;
>>>>> +
>>>>> +	mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_ua_to_hpa(mem, ua, &hpa)))
>>>>> +		return H_HARDWARE;
>>>>
>>>> Remind me - could a failure here be triggered by userspace failing to
>>>> preregister all the memory it should?
>>>
>>>
>>> mm_iommu_lookup() should fail first as the only reason for
>>> mm_iommu_ua_to_hpa() to fail is (entry >= mem->entries) but this is checked
>>> in mm_iommu_lookup().
>>
>> Ah, yes of course, I forgot.  Ok, that should be fine.
>>
>>
>>>>
>>>>> +	if (mm_iommu_mapped_inc(mem))
>>>>> +		return H_CLOSED;
>>>>> +
>>>>> +	ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
>>>>> +	if (ret) {
>>>>> +		mm_iommu_mapped_dec(mem);
>>>>> +		return H_TOO_HARD;
>>>>> +	}
>>>>> +
>>>>> +	if (dir != DMA_NONE)
>>>>> +		kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +
>>>>> +	*pua = ua;
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  		      unsigned long ioba, unsigned long tce)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>> -	long ret;
>>>>> +	long ret, idx;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	unsigned long entry, gpa;
>>>>> +	enum dma_data_direction dir;
>>>>>
>>>>>  	/* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>>>>>  	/* 	    liobn, ioba, tce); */
>>>>> @@ -230,7 +482,28 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu,
unsigned long liobn,
>>>>>  	if (ret != H_SUCCESS)
>>>>>  		return ret;
>>>>>
>>>>> -	kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>>>> +	entry = ioba >> stt->page_shift;
>>>>> +	gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +	dir = iommu_tce_direction(tce);
>>>>> +
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		if (dir == DMA_NONE) {
>>>>> +			ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry);
>>>>> +		} else {
>>>>> +			idx = srcu_read_lock(&vcpu->kvm->srcu);
>>>>> +			ret = kvmppc_tce_iommu_map(vcpu->kvm, stit->tbl,
>>>>> +					entry, gpa, dir);
>>>>> +			srcu_read_unlock(&vcpu->kvm->srcu, idx);
>>>>> +		}
>>>>> +
>>>>> +		if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +			kvmppc_clear_tce(stit->tbl, entry);
>>>>> +		else if (ret != H_SUCCESS)
>>>>> +			return ret;
>>>>> +	}
>>>>> +
>>>>> +	kvmppc_tce_put(stt, entry, tce);
>>>>>
>>>>>  	return H_SUCCESS;
>>>>>  }
>>>>> @@ -242,9 +515,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu
*vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret = H_SUCCESS, idx;
>>>>> -	unsigned long entry, ua = 0;
>>>>> +	unsigned long entry, ua = 0, gpa;
>>>>>  	u64 __user *tces;
>>>>>  	u64 tce;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -283,6 +557,18 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu
*vcpu,
>>>>>  		if (ret != H_SUCCESS)
>>>>>  			goto unlock_exit;
>>>>>
>>>>> +		gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +
>>>>> +		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +			ret = kvmppc_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry + i, gpa,
>>>>> +					iommu_tce_direction(tce));
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				goto unlock_exit;
>>>>> +		}
>>>>> +
>>>>>  		kvmppc_tce_put(stt, entry + i, tce);
>>>>>  	}
>>>>>
>>>>> @@ -299,6 +585,7 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -312,6 +599,20 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  	if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
>>>>>  		return H_PARAMETER;
>>>>>
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		unsigned long entry = ioba >> stit->tbl->it_page_shift;
>>>>> +
>>>>> +		for (i = 0; i < npages; ++i) {
>>>>> +			ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry + i);
>>>>> +
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				return ret;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>>  	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
>>>>>  		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);
>>>>>
>>>>> diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c
b/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> index 92d769f4eaea..4a1d978ebd98 100644
>>>>> --- a/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
>>>>> @@ -161,11 +161,111 @@ long kvmppc_gpa_to_ua(struct kvm *kvm,
unsigned long gpa,
>>>>>  EXPORT_SYMBOL_GPL(kvmppc_gpa_to_ua);
>>>>>
>>>>>  #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
>>>>> +static void kvmppc_rm_clear_tce(struct iommu_table *tbl, unsigned
long entry)
>>>>> +{
>>>>> +	unsigned long hpa = 0;
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +
>>>>> +	iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	struct mm_iommu_table_group_mem_t *mem = NULL;
>>>>> +	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	pua = (void *) vmalloc_to_phys(pua);
>>>>> +	if (!pua)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mem = mm_iommu_lookup_rm(kvm->mm, *pua, pgsize);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	mm_iommu_mapped_dec(mem);
>>>>> +
>>>>> +	*pua = 0;
>>>>> +
>>>>> +	return H_SUCCESS;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_unmap(struct kvm *kvm,
>>>>> +		struct iommu_table *tbl, unsigned long entry)
>>>>> +{
>>>>> +	enum dma_data_direction dir = DMA_NONE;
>>>>> +	unsigned long hpa = 0;
>>>>> +	long ret;
>>>>> +
>>>>> +	if (iommu_tce_xchg_rm(tbl, entry, &hpa, &dir))
>>>>> +		return H_HARDWARE;
>>>>
>>>> To avoid a double WARN() (and to make the warnings easier to
>>>> understand) I'd suggest putting a WARN_ON() here, rather than in the
>>>> callers when they receieve an H_HARDWARE.  IIUC this really shouldn't
>>>> ever happen, and it certainly can't be the guest's fault?
>>>
>>>
>>> Makes sense.
>>
>> I guess it might want WARN_ON_ONCE() to avoid spamming the user with
>> errors for every TCE, though.
>
>
> We do not expect this to happen at all :) I can convert all of them to
> _ONCE really as the purpose of WARN_ON is mostly to document what we do not
> expect.
>
>
>
>>>>> +
>>>>> +	if (dir == DMA_NONE)
>>>>> +		return H_SUCCESS;
>>>>> +
>>>>> +	ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +	if (ret)
>>>>> +		iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static long kvmppc_rm_tce_iommu_map(struct kvm *kvm, struct
iommu_table *tbl,
>>>>> +		unsigned long entry, unsigned long gpa,
>>>>> +		enum dma_data_direction dir)
>>>>> +{
>>>>> +	long ret;
>>>>> +	unsigned long hpa = 0, ua;
>>>>> +	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>>>>> +	struct mm_iommu_table_group_mem_t *mem;
>>>>> +
>>>>> +	if (!pua)
>>>>> +		/* it_userspace allocation might be delayed */
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (kvmppc_gpa_to_ua(kvm, gpa, &ua, NULL))
>>>>> +		return H_PARAMETER;
>>>
>>>
>>> Referred below as [1]
>>>
>>>
>>>>> +
>>>>> +	mem = mm_iommu_lookup_rm(kvm->mm, ua, 1ULL << tbl->it_page_shift);
>>>>> +	if (!mem)
>>>>> +		return H_TOO_HARD;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_ua_to_hpa_rm(mem, ua, &hpa)))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	pua = (void *) vmalloc_to_phys(pua);
>>>>> +	if (WARN_ON(!pua))
>>>>> +		return H_HARDWARE;
>>>>> +
>>>>> +	if (WARN_ON(mm_iommu_mapped_inc(mem)))
>>>>> +		return H_CLOSED;
>>>>> +
>>>>> +	ret = iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
>>>>> +	if (ret) {
>>>>> +		mm_iommu_mapped_dec(mem);
>>>>> +		return H_TOO_HARD;
>>>>> +	}
>>>>> +
>>>>> +	if (dir != DMA_NONE)
>>>>> +		kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
>>>>> +
>>>>> +	*pua = ua;
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
>>>>>  		unsigned long ioba, unsigned long tce)
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>> +	unsigned long entry, gpa;
>>>>> +	enum dma_data_direction dir;
>>>>>
>>>>>  	/* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
>>>>>  	/* 	    liobn, ioba, tce); */
>>>>> @@ -182,7 +282,25 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu,
unsigned long liobn,
>>>>>  	if (ret != H_SUCCESS)
>>>>>  		return ret;
>>>>>
>>>>> -	kvmppc_tce_put(stt, ioba >> stt->page_shift, tce);
>>>>> +	entry = ioba >> stt->page_shift;
>>>>> +	gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +	dir = iommu_tce_direction(tce);
>>>>> +
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		if (dir == DMA_NONE)
>>>>> +			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry);
>>>>> +		else
>>>>> +			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry, gpa, dir);
>>>>> +
>>>>> +		if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +			kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>> +		else if (ret != H_SUCCESS)
>>>>> +			return ret;
>>>>> +	}
>>>>> +
>>>>> +	kvmppc_tce_put(stt, entry, tce);
>>>>>
>>>>>  	return H_SUCCESS;
>>>>>  }
>>>>> @@ -220,9 +338,10 @@ long kvmppc_rm_h_put_tce_indirect(struct
kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret = H_SUCCESS;
>>>>> -	unsigned long tces, entry, ua = 0;
>>>>> +	unsigned long tces, entry, ua = 0, tce, gpa;
>>>>>  	unsigned long *rmap = NULL;
>>>>>  	bool prereg = false;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -287,12 +406,24 @@ long kvmppc_rm_h_put_tce_indirect(struct
kvm_vcpu *vcpu,
>>>>>  	}
>>>>>
>>>>>  	for (i = 0; i < npages; ++i) {
>>>>> -		unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
>>>>> +		tce = be64_to_cpu(((u64 *)tces)[i]);
>>>>>
>>>>>  		ret = kvmppc_tce_validate(stt, tce);
>>>>>  		if (ret != H_SUCCESS)
>>>>>  			goto unlock_exit;
>>>>>
>>>>> +		gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
>>>>> +
>>>>> +		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm,
>>>>> +					stit->tbl, entry + i, gpa,
>>>>> +					iommu_tce_direction(tce));
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>
>>>> I don't think you need the WARN() here - the only H_HARDWARE failure
>>>> path in iommu_map() already includes a WARN().
>>>
>>>
>>> True, I can drop it here.
>>>
>>>
>>>>
>>>>> +				kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				goto unlock_exit;
>>>>
>>>> It's also not clear to me why the H_HARDWARE error path clears the
>>>> entry, but the other failure paths don't.  Or why an H_HARDWARE will
>>>> result in continuing to set the rest of the TCEs, but other failures
>>>> won't.
>>>
>>>
>>> The idea was that other failures still have some chance that handling may
>>> succeed in virtual mode or via QEMU, H_HARDWARE is fatal.
>>
>> Um... yes.. but the logic seems to be backwards for that: on
>> H_HARDWARE you warn and keep going, on other errors you bail out
>> entirely.
>
> By "fatal" I means fatal for this particular hardware TCE(s), no hope in
> trying this particular TCE in virtual mode.
>
>
>>
>>> I am just not sure if H_PARAMETER is what I want to return at [1], to make
>>> the calling code simplier, I could return H_HARDWARE there as well (instead
>>> of H_PARAMETER).
>>
>> That sounds right, IIUC the gpa to ua translation shouldn't ever
>> fail because of something the guest did.
>
>
> The guest can easily pass bad TCE/GPA which is not in any registered slot.
> So it is rather H_PARAMETER.
>
>> So I'd expect either
>> H_HARDWARE, or H_TOO_HARD (if there's some hope that virtual mode can
>> make the translation when real mode couldn't).
>
> No, virtual mode uses the exact same helper.
>
>
>>>>> +		}
>>>>> +
>>>>>  		kvmppc_tce_put(stt, entry + i, tce);
>>>>>  	}
>>>>>
>>>>> @@ -309,6 +440,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  {
>>>>>  	struct kvmppc_spapr_tce_table *stt;
>>>>>  	long i, ret;
>>>>> +	struct kvmppc_spapr_tce_iommu_table *stit;
>>>>>
>>>>>  	stt = kvmppc_find_table(vcpu->kvm, liobn);
>>>>>  	if (!stt)
>>>>> @@ -322,6 +454,20 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
>>>>>  	if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
>>>>>  		return H_PARAMETER;
>>>>>
>>>>> +	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
>>>>> +		unsigned long entry = ioba >> stit->tbl->it_page_shift;
>>>>> +
>>>>> +		for (i = 0; i < npages; ++i) {
>>>>> +			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm,
>>>>> +					stit->tbl, entry + i);
>>>>> +
>>>>> +			if (WARN_ON_ONCE(ret == H_HARDWARE))
>>>>> +				kvmppc_rm_clear_tce(stit->tbl, entry);
>>>>
>>>> As noted earlier, I think this WARN belongs within iommu_unmap()
>>>> rather than out here.
>>>>
>>>>> +			else if (ret != H_SUCCESS)
>>>>> +				return ret;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>>  	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
>>>>>  		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);
>>>>>
>>>>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>>>>> index cd892dec7cb6..f3127dc87912 100644
>>>>> --- a/arch/powerpc/kvm/powerpc.c
>>>>> +++ b/arch/powerpc/kvm/powerpc.c
>>>>> @@ -536,6 +536,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm,
long ext)
>>>>>  #ifdef CONFIG_PPC_BOOK3S_64
>>>>>  	case KVM_CAP_SPAPR_TCE:
>>>>>  	case KVM_CAP_SPAPR_TCE_64:
>>>>> +		/* fallthrough */
>>>>> +	case KVM_CAP_SPAPR_TCE_VFIO:
>>>>>  	case KVM_CAP_PPC_RTAS:
>>>>>  	case KVM_CAP_PPC_FIXUP_HCALL:
>>>>>  	case KVM_CAP_PPC_ENABLE_HCALL:
>>>>> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
>>>>> index d32f239eb471..2b7dc22265fe 100644
>>>>> --- a/virt/kvm/vfio.c
>>>>> +++ b/virt/kvm/vfio.c
>>>>> @@ -20,6 +20,10 @@
>>>>>  #include <linux/vfio.h>
>>>>>  #include "vfio.h"
>>>>>
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +#include <asm/kvm_ppc.h>
>>>>> +#endif
>>>>> +
>>>>>  struct kvm_vfio_group {
>>>>>  	struct list_head node;
>>>>>  	struct vfio_group *vfio_group;
>>>>> @@ -211,6 +215,9 @@ static int kvm_vfio_set_group(struct kvm_device
*dev, long attr, u64 arg)
>>>>>
>>>>>  		mutex_unlock(&kv->lock);
>>>>>
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		kvm_spapr_tce_release_iommu_group(dev->kvm, vfio_group);
>>>>> +#endif
>>>>>  		kvm_vfio_group_set_kvm(vfio_group, NULL);
>>>>>
>>>>>  		kvm_vfio_group_put_external_user(vfio_group);
>>>>> @@ -218,6 +225,53 @@ static int kvm_vfio_set_group(struct kvm_device
*dev, long attr, u64 arg)
>>>>>  		kvm_vfio_update_coherency(dev);
>>>>>
>>>>>  		return ret;
>>>>> +
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: {
>>>>> +		struct kvm_vfio_spapr_tce param;
>>>>> +		unsigned long minsz;
>>>>> +		struct kvm_vfio *kv = dev->private;
>>>>> +		struct vfio_group *vfio_group;
>>>>> +		struct kvm_vfio_group *kvg;
>>>>> +		struct fd f;
>>>>> +
>>>>> +		minsz = offsetofend(struct kvm_vfio_spapr_tce, tablefd);
>>>>> +
>>>>> +		if (copy_from_user(&param, (void __user *)arg, minsz))
>>>>> +			return -EFAULT;
>>>>> +
>>>>> +		if (param.argsz < minsz || param.flags)
>>>>> +			return -EINVAL;
>>>>> +
>>>>> +		f = fdget(param.groupfd);
>>>>> +		if (!f.file)
>>>>> +			return -EBADF;
>>>>> +
>>>>> +		vfio_group = kvm_vfio_group_get_external_user(f.file);
>>>>> +		fdput(f);
>>>>> +
>>>>> +		if (IS_ERR(vfio_group))
>>>>> +			return PTR_ERR(vfio_group);
>>>>> +
>>>>> +		ret = -ENOENT;
>>>>> +
>>>>> +		mutex_lock(&kv->lock);
>>>>> +
>>>>> +		list_for_each_entry(kvg, &kv->group_list, node) {
>>>>> +			if (kvg->vfio_group != vfio_group)
>>>>> +				continue;
>>>>> +
>>>>> +			ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
>>>>> +					param.tablefd, vfio_group);
>>>>> +
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +		mutex_unlock(&kv->lock);
>>>>> +
>>>>> +		return ret;
>>>>> +	}
>>>>> +#endif /* CONFIG_SPAPR_TCE_IOMMU */
>>>>>  	}
>>>>>
>>>>>  	return -ENXIO;
>>>>> @@ -242,6 +296,9 @@ static int kvm_vfio_has_attr(struct kvm_device *dev,
>>>>>  		switch (attr->attr) {
>>>>>  		case KVM_DEV_VFIO_GROUP_ADD:
>>>>>  		case KVM_DEV_VFIO_GROUP_DEL:
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
>>>>> +#endif
>>>>>  			return 0;
>>>>>  		}
>>>>>
>>>>> @@ -257,6 +314,9 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
>>>>>  	struct kvm_vfio_group *kvg, *tmp;
>>>>>
>>>>>  	list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
>>>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>>>> +		kvm_spapr_tce_release_iommu_group(dev->kvm, kvg->vfio_group);
>>>>> +#endif
>>>>>  		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
>>>>>  		kvm_vfio_group_put_external_user(kvg->vfio_group);
>>>>>  		list_del(&kvg->node);
>>>>
>>>
>>>
>>
>>
>>
>>
>
>

-- 
Alexey

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