On 03/10/2016 04:21 PM, David Gibson wrote:
On Wed, Mar 09, 2016 at 08:20:12PM +1100, Alexey Kardashevskiy wrote:
On 03/09/2016 04:45 PM, David Gibson wrote:
On Mon, Mar 07, 2016 at 02:41:17PM +1100, Alexey Kardashevskiy wrote:
sPAPR TCE IOMMU is para-virtualized and the guest does map/unmap
via hypercalls which take a logical bus id (LIOBN) as a target IOMMU
identifier. LIOBNs are made up, advertised to guest systems and
linked to IOMMU groups by the user space.
In order to enable acceleration for IOMMU operations in KVM, we need
to tell KVM the information about the LIOBN-to-group mapping.
For that, a new KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN parameter
is added which accepts:
- a VFIO group fd and IO base address to find the actual hardware
TCE table;
- a LIOBN to assign to the found table.
Before notifying KVM about new link, this check the group for being
registered with KVM device in order to release them at unexpected KVM
finish.
This advertises the new KVM_CAP_SPAPR_TCE_VFIO capability to the user
space.
While we are here, this also fixes VFIO KVM device compiling to let it
link to a KVM module.
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Documentation/virtual/kvm/devices/vfio.txt | 21 +++++-
arch/powerpc/kvm/Kconfig | 1 +
arch/powerpc/kvm/Makefile | 5 +-
arch/powerpc/kvm/powerpc.c | 1 +
include/uapi/linux/kvm.h | 9 +++
virt/kvm/vfio.c | 106 +++++++++++++++++++++++++++++
6 files changed, 140 insertions(+), 3 deletions(-)
diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt
index ef51740..c0d3eb7 100644
--- a/Documentation/virtual/kvm/devices/vfio.txt
+++ b/Documentation/virtual/kvm/devices/vfio.txt
@@ -16,7 +16,24 @@ 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.
AFAICT these changes are accurate for VFIO as it is already, in which
case it might be clearer to put them in a separate patch.
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.
-For each, kvm_device_attr.addr points to an int32_t file descriptor
-for the VFIO group.
+ KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN: sets a liobn for a VFIO group
+ kvm_device_attr.addr points to a struct:
+ struct kvm_vfio_spapr_tce_liobn {
+ __u32 argsz;
+ __s32 fd;
+ __u32 liobn;
+ __u8 pad[4];
+ __u64 start_addr;
+ };
+ where
+ @argsz is the size of kvm_vfio_spapr_tce_liobn;
+ @fd is a file descriptor for a VFIO group;
+ @liobn is a logical bus id to be associated with the group;
+ @start_addr is a DMA window offset on the IO (PCI) bus
For the cause of DDW and multiple windows, I'm assuming you can call
this multiple times with different LIOBNs and the same IOMMU group?
Yes. It is called twice per each group (when DDW is activated) - for 32bit
and 64bit windows, this is why @start_addr is there.
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 1059846..dfa3488 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -65,6 +65,7 @@ config KVM_BOOK3S_64
select KVM
select KVM_BOOK3S_PR_POSSIBLE if !KVM_BOOK3S_HV_POSSIBLE
select SPAPR_TCE_IOMMU if IOMMU_SUPPORT
+ select KVM_VFIO if VFIO
---help---
Support running unmodified book3s_64 and book3s_32 guest kernels
in virtual machines on book3s_64 host processors.
diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
index 7f7b6d8..71f577c 100644
--- a/arch/powerpc/kvm/Makefile
+++ b/arch/powerpc/kvm/Makefile
@@ -8,7 +8,7 @@ ccflags-y := -Ivirt/kvm -Iarch/powerpc/kvm
KVM := ../../../virt/kvm
common-objs-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o \
- $(KVM)/eventfd.o $(KVM)/vfio.o
+ $(KVM)/eventfd.o
Please don't disable the VFIO device for the non-book3s case. I added
it (even though it didn't do anything until now) so that libvirt
wouldn't choke when it finds it's not available. Obviously the new
ioctl needs to be only for the right IOMMU setup, but the device
itself should be available always.
Ah. Ok, I'll fix this. I just wanted to be able to compile kvm as a module.
CFLAGS_e500_mmu.o := -I.
CFLAGS_e500_mmu_host.o := -I.
@@ -87,6 +87,9 @@ endif
kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \
book3s_xics.o
+kvm-book3s_64-objs-$(CONFIG_KVM_VFIO) += \
+ $(KVM)/vfio.o \
+
kvm-book3s_64-module-objs += \
$(KVM)/kvm_main.o \
$(KVM)/eventfd.o \
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 19aa59b..63f188d 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -521,6 +521,7 @@ 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:
+ case KVM_CAP_SPAPR_TCE_VFIO:
case KVM_CAP_PPC_ALLOC_HTAB:
case KVM_CAP_PPC_RTAS:
case KVM_CAP_PPC_FIXUP_HCALL:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 080ffbf..f1abbea 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1056,6 +1056,7 @@ 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_LIOBN 3
enum kvm_device_type {
KVM_DEV_TYPE_FSL_MPIC_20 = 1,
@@ -1075,6 +1076,14 @@ enum kvm_device_type {
KVM_DEV_TYPE_MAX,
};
+struct kvm_vfio_spapr_tce_liobn {
+ __u32 argsz;
+ __s32 fd;
+ __u32 liobn;
+ __u8 pad[4];
+ __u64 start_addr;
+};
+
/*
* ioctls for VM fds
*/
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 1dd087d..87c771e 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;
@@ -60,6 +64,22 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *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;
Should this be -ESOMETHING?
+ 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 bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
{
long (*fn)(struct vfio_group *, unsigned long);
@@ -110,6 +130,22 @@ static void kvm_vfio_update_coherency(struct kvm_device *dev)
mutex_unlock(&kv->lock);
}
+#ifdef CONFIG_SPAPR_TCE_IOMMU
+static void kvm_vfio_spapr_detach_iommu_group(struct kvm *kvm,
+ struct vfio_group *vfio_group)
Shouldn't this go in the same patch that introduced the attach
function?
Having less patches which touch different maintainers areas is better. I
cannot avoid touching both PPC KVM and VFIO in this patch but I can in
"[PATCH kernel 6/9] KVM: PPC: Associate IOMMU group with guest view of TCE
table".
+{
+ int group_id;
+ struct iommu_group *grp;
+
+ group_id = kvm_vfio_external_user_iommu_id(vfio_group);
+ grp = iommu_group_get_by_id(group_id);
+ if (grp) {
+ kvm_spapr_tce_detach_iommu_group(kvm, grp);
+ iommu_group_put(grp);
+ }
+}
+#endif
+
static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
{
struct kvm_vfio *kv = dev->private;
@@ -186,6 +222,10 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
continue;
list_del(&kvg->node);
+#ifdef CONFIG_SPAPR_TCE_IOMMU
Better to make a no-op version of the call than have to #ifdef at the
callsite.
It is questionable. A x86 reader may decide that
KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE_LIOBN is implemented for x86 and get
confused.
+ kvm_vfio_spapr_detach_iommu_group(dev->kvm,
+ kvg->vfio_group);
+#endif
kvm_vfio_group_put_external_user(kvg->vfio_group);
kfree(kvg);
ret = 0;
@@ -201,6 +241,69 @@ 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_LIOBN: {
+ struct kvm_vfio_spapr_tce_liobn 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_liobn,
+ start_addr);
+
+ if (copy_from_user(¶m, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (param.argsz < minsz)
+ return -EINVAL;
+
+ f = fdget(param.fd);
+ 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;
Shouldn't there be some runtime test for the type of the IOMMU? It's
possible a kernel could be built for a platform supporting multiple
IOMMU types.
Well, may make sense but I do not know to test that. The IOMMU type is a
VFIO container property, not a group property and here (KVM) we only have
groups.
Which, as mentioned previously, is broken.
Which I am failing to follow you on this.
What I am trying to achieve here is pretty much referencing a group so it
cannot be reused. Plus LIOBNs. Passing a container fd does not make much
sense here as the VFIO device would walk through groups, reference them and
that is it, there is no locking on VFIO containters and so far there was no
need to teach KVM about containers.
What do I miss now?
And calling iommu_group_get_iommudata() is quite useless as it returns a
void pointer... I could probably check that the release() callback is the
one I set via iommu_group_set_iommudata() but there is no API to get it from
a group.
And I cannot really imagine a kernel with CONFIG_PPC_BOOK3S_64 (and
therefore KVM_CAP_SPAPR_TCE_VFIO enabled) with different IOMMU types. Can
the same kernel binary image work on both BOOK3S and embedded PPC? Where
these other types can come from?
+ mutex_lock(&kv->lock);
+
+ list_for_each_entry(kvg, &kv->group_list, node) {
+ int group_id;
+ struct iommu_group *grp;
+
+ if (kvg->vfio_group != vfio_group)
+ continue;
+
+ group_id = kvm_vfio_external_user_iommu_id(
+ kvg->vfio_group);
+ grp = iommu_group_get_by_id(group_id);
+ if (!grp) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = kvm_spapr_tce_attach_iommu_group(dev->kvm,
+ param.liobn, param.start_addr,
+ grp);
+ if (ret)
+ iommu_group_put(grp);
+ break;
+ }
+
+ mutex_unlock(&kv->lock);
+
+ kvm_vfio_group_put_external_user(vfio_group);
+
+ return ret;
+ }
+#endif /* CONFIG_SPAPR_TCE_IOMMU */
}
return -ENXIO;
@@ -225,6 +328,9 @@ 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_LIOBN:
+#endif
return 0;
}
--
Alexey
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