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(¶m, (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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