Re: [PATCH v3 03/16] iommufd/viommu: Add IOMMU_VDEVICE_ALLOC ioctl

2024-10-21 Thread Nicolin Chen 
On Mon, Oct 21, 2024 at 09:22:48AM -0300, Jason Gunthorpe wrote:
> On Sat, Oct 19, 2024 at 06:42:30PM -0700, Nicolin Chen wrote:
> > > But be mindful of this abort, it doesn't want to be inside the lock if
> > > it also gets the lock.. fail_nth should be updated to cover these new
> > > ioctls to look for tricky things like that
> > 
> > I added an abort() beside destroy():
> > 
> > +void iommufd_vdevice_abort(struct iommufd_object *obj)
> > +{
> > +   struct iommufd_vdevice *old, *vdev =
> > +   container_of(obj, struct iommufd_vdevice, obj);
> > +   struct iommufd_viommu *viommu = vdev->viommu;
> > +   struct iommufd_device *idev = vdev->idev;
> > +
> > +   lockdep_assert_not_held(&idev->igroup->lock);
> 
> ???

Oops. That's a typo from auto-completion.

> > +void iommufd_vdevice_destroy(struct iommufd_object *obj)
> > +{
> > +   struct iommufd_vdevice *vdev =
> > +   container_of(obj, struct iommufd_vdevice, obj);
> > +
> > +   mutex_lock(&vdev->idev->igroup->lock);
> > +   iommufd_vdevice_abort(obj);
> 
> When we get it here??

LOCKDEP wasn't enabled when I tested it.. Just fixed and retested.

Thanks
Nicolin

Re: [PATCH v3 03/16] iommufd/viommu: Add IOMMU_VDEVICE_ALLOC ioctl

2024-10-21 Thread Jason Gunthorpe 
On Sat, Oct 19, 2024 at 06:42:30PM -0700, Nicolin Chen wrote:
> > But be mindful of this abort, it doesn't want to be inside the lock if
> > it also gets the lock.. fail_nth should be updated to cover these new
> > ioctls to look for tricky things like that
> 
> I added an abort() beside destroy():
> 
> +void iommufd_vdevice_abort(struct iommufd_object *obj)
> +{
> +   struct iommufd_vdevice *old, *vdev =
> +   container_of(obj, struct iommufd_vdevice, obj);
> +   struct iommufd_viommu *viommu = vdev->viommu;
> +   struct iommufd_device *idev = vdev->idev;
> +
> +   lockdep_assert_not_held(&idev->igroup->lock);

???

> +
> +   if (viommu->ops && viommu->ops->vdevice_free)
> +   viommu->ops->vdevice_free(vdev);
> +
> +   old = xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
> +   if (old)
> +   WARN_ON(old != vdev);
> +
> +   refcount_dec(&viommu->obj.users);
> +   refcount_dec(&idev->obj.users);
> +   idev->vdev = NULL;
> +}
> +
> +void iommufd_vdevice_destroy(struct iommufd_object *obj)
> +{
> +   struct iommufd_vdevice *vdev =
> +   container_of(obj, struct iommufd_vdevice, obj);
> +
> +   mutex_lock(&vdev->idev->igroup->lock);
> +   iommufd_vdevice_abort(obj);

When we get it here??

Jason

Re: [PATCH v3 03/16] iommufd/viommu: Add IOMMU_VDEVICE_ALLOC ioctl

2024-10-19 Thread Nicolin Chen 
On Thu, Oct 17, 2024 at 03:52:30PM -0300, Jason Gunthorpe wrote:
> > +   if (viommu->ops && viommu->ops->vdevice_alloc)
> > +   vdev = viommu->ops->vdevice_alloc(viommu, idev->dev, virt_id);
> > +   else
> > +   vdev = __iommufd_vdevice_alloc(ucmd->ictx, sizeof(*vdev));
> > +   if (IS_ERR(vdev)) {
> > +   rc = PTR_ERR(vdev);
> > +   goto out_unlock_igroup;
> > +   }
> > +
> > +   vdev->idev = idev;
> > +   vdev->id = virt_id;
> > +   vdev->viommu = viommu;
> > +
> > +   idev->vdev = vdev;
> > +   refcount_inc(&idev->obj.users);
> > +   refcount_inc(&viommu->obj.users);
> > +
> > +   curr = xa_cmpxchg(&viommu->vdevs, virt_id, NULL, vdev, GFP_KERNEL);
> > +   if (curr) {
> > +   rc = xa_err(curr) ? : -EBUSY;
> > +   goto out_abort;
> > +   }
> > +
> > +   cmd->out_vdevice_id = vdev->obj.id;
> > +   rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> > +   if (rc)
> > +   goto out_abort;
> > +   iommufd_object_finalize(ucmd->ictx, &vdev->obj);
> > +   goto out_unlock_igroup;
> > +
> > +out_abort:
> > +   iommufd_object_abort_and_destroy(ucmd->ictx, &vdev->obj);
> 
> But be mindful of this abort, it doesn't want to be inside the lock if
> it also gets the lock.. fail_nth should be updated to cover these new
> ioctls to look for tricky things like that

I added an abort() beside destroy():

+void iommufd_vdevice_abort(struct iommufd_object *obj)
+{
+   struct iommufd_vdevice *old, *vdev =
+   container_of(obj, struct iommufd_vdevice, obj);
+   struct iommufd_viommu *viommu = vdev->viommu;
+   struct iommufd_device *idev = vdev->idev;
+
+   lockdep_assert_not_held(&idev->igroup->lock);
+
+   if (viommu->ops && viommu->ops->vdevice_free)
+   viommu->ops->vdevice_free(vdev);
+
+   old = xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
+   if (old)
+   WARN_ON(old != vdev);
+
+   refcount_dec(&viommu->obj.users);
+   refcount_dec(&idev->obj.users);
+   idev->vdev = NULL;
+}
+
+void iommufd_vdevice_destroy(struct iommufd_object *obj)
+{
+   struct iommufd_vdevice *vdev =
+   container_of(obj, struct iommufd_vdevice, obj);
+
+   mutex_lock(&vdev->idev->igroup->lock);
+   iommufd_vdevice_abort(obj);
+   mutex_unlock(&vdev->idev->igroup->lock);
+}
--

And I added fail_nth coverage for IOMMU_VIOMMU/VDEVICE_ALLOC cmds.

Thanks
Nicolin

Re: [PATCH v3 03/16] iommufd/viommu: Add IOMMU_VDEVICE_ALLOC ioctl

2024-10-17 Thread Jason Gunthorpe 
On Wed, Oct 09, 2024 at 09:38:15AM -0700, Nicolin Chen wrote:
> +void iommufd_vdevice_destroy(struct iommufd_object *obj)
> +{
> + struct iommufd_vdevice *old, *vdev =
> + container_of(obj, struct iommufd_vdevice, obj);
> + struct iommufd_viommu *viommu = vdev->viommu;
> + struct iommufd_device *idev = vdev->idev;
> +
> + if (viommu->ops && viommu->ops->vdevice_free)
> + viommu->ops->vdevice_free(vdev);
> +
> + old = xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
> + if (old)
> + WARN_ON(old != vdev);
> +
> + refcount_dec(&viommu->obj.users);
> + refcount_dec(&idev->obj.users);
> + idev->vdev = NULL;

This should hold the igroup lock when touching vdev?

> +int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
> +{
> + struct iommu_vdevice_alloc *cmd = ucmd->cmd;
> + struct iommufd_vdevice *vdev, *curr;
> + struct iommufd_viommu *viommu;
> + struct iommufd_device *idev;
> + u64 virt_id = cmd->virt_id;
> + int rc = 0;
> +
> + if (virt_id > ULONG_MAX)
> + return -EINVAL;
> +
> + viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
> + if (IS_ERR(viommu))
> + return PTR_ERR(viommu);
> +
> + idev = iommufd_get_device(ucmd, cmd->dev_id);
> + if (IS_ERR(idev)) {
> + rc = PTR_ERR(idev);
> + goto out_put_viommu;
> + }
> +
> + mutex_lock(&idev->igroup->lock);
> + if (idev->vdev) {
> + rc = -EEXIST;
> + goto out_unlock_igroup;
> + }

Otherwise this won't work right

> + if (viommu->ops && viommu->ops->vdevice_alloc)
> + vdev = viommu->ops->vdevice_alloc(viommu, idev->dev, virt_id);
> + else
> + vdev = __iommufd_vdevice_alloc(ucmd->ictx, sizeof(*vdev));
> + if (IS_ERR(vdev)) {
> + rc = PTR_ERR(vdev);
> + goto out_unlock_igroup;
> + }
> +
> + vdev->idev = idev;
> + vdev->id = virt_id;
> + vdev->viommu = viommu;
> +
> + idev->vdev = vdev;
> + refcount_inc(&idev->obj.users);
> + refcount_inc(&viommu->obj.users);
> +
> + curr = xa_cmpxchg(&viommu->vdevs, virt_id, NULL, vdev, GFP_KERNEL);
> + if (curr) {
> + rc = xa_err(curr) ? : -EBUSY;
> + goto out_abort;
> + }
> +
> + cmd->out_vdevice_id = vdev->obj.id;
> + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> + if (rc)
> + goto out_abort;
> + iommufd_object_finalize(ucmd->ictx, &vdev->obj);
> + goto out_unlock_igroup;
> +
> +out_abort:
> + iommufd_object_abort_and_destroy(ucmd->ictx, &vdev->obj);

But be mindful of this abort, it doesn't want to be inside the lock if
it also gets the lock.. fail_nth should be updated to cover these new
ioctls to look for tricky things like that

But the design looks OK

Jason

[PATCH v3 03/16] iommufd/viommu: Add IOMMU_VDEVICE_ALLOC ioctl

2024-10-09 Thread Nicolin Chen 
Introduce a new ioctl to allocate a vDEVICE object. Since a vDEVICE object
is a connection of an iommufd_iommufd object and an iommufd_viommu object,
require both as the ioctl inputs and take refcounts in the ioctl handler.

Add to the vIOMMU object a "vdevs" xarray, indexed by a per-vIOMMU virtual
device ID, which can be:
 - Virtual StreamID on a nested ARM SMMUv3, an index to a Stream Table
 - Virtual DeviceID on a nested AMD IOMMU, an index to a Device Table
 - Virtual ID on a nested Intel VT-D IOMMU, an index to a Context Table

Signed-off-by: Nicolin Chen 
---
 drivers/iommu/iommufd/iommufd_private.h | 11 +++
 include/linux/iommufd.h |  2 +
 include/uapi/linux/iommufd.h| 26 +++
 drivers/iommu/iommufd/main.c|  6 ++
 drivers/iommu/iommufd/viommu.c  | 91 +
 5 files changed, 136 insertions(+)

diff --git a/drivers/iommu/iommufd/iommufd_private.h 
b/drivers/iommu/iommufd/iommufd_private.h
index 0c56a467e440..e160edb22b67 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -409,6 +409,7 @@ struct iommufd_device {
struct iommufd_object obj;
struct iommufd_ctx *ictx;
struct iommufd_group *igroup;
+   struct iommufd_vdevice *vdev;
struct list_head group_item;
/* always the physical device */
struct device *dev;
@@ -523,8 +524,18 @@ static inline int iommufd_hwpt_replace_device(struct 
iommufd_device *idev,
return iommu_group_replace_domain(idev->igroup->group, hwpt->domain);
 }
 
+static inline struct iommufd_viommu *
+iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
+{
+   return container_of(iommufd_get_object(ucmd->ictx, id,
+  IOMMUFD_OBJ_VIOMMU),
+   struct iommufd_viommu, obj);
+}
+
 int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd);
 void iommufd_viommu_destroy(struct iommufd_object *obj);
+int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd);
+void iommufd_vdevice_destroy(struct iommufd_object *obj);
 
 #ifdef CONFIG_IOMMUFD_TEST
 int iommufd_test(struct iommufd_ucmd *ucmd);
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 510fc961a9ad..5a630952150d 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -72,6 +72,8 @@ struct iommufd_viommu {
 
const struct iommufd_viommu_ops *ops;
 
+   struct xarray vdevs;
+
unsigned int type;
 };
 
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 6ee841a8c79b..3039519d71b7 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -52,6 +52,7 @@ enum {
IOMMUFD_CMD_HWPT_INVALIDATE = 0x8d,
IOMMUFD_CMD_FAULT_QUEUE_ALLOC = 0x8e,
IOMMUFD_CMD_VIOMMU_ALLOC = 0x8f,
+   IOMMUFD_CMD_VDEVICE_ALLOC = 0x90,
 };
 
 /**
@@ -894,4 +895,29 @@ struct iommu_viommu_alloc {
__u32 out_viommu_id;
 };
 #define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
+
+/**
+ * struct iommu_vdevice_alloc - ioctl(IOMMU_VDEVICE_ALLOC)
+ * @size: sizeof(struct iommu_vdevice_alloc)
+ * @viommu_id: vIOMMU ID to associate with the virtual device
+ * @dev_id: The pyhsical device to allocate a virtual instance on the vIOMMU
+ * @__reserved: Must be 0
+ * @virt_id: Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID
+ *   of AMD IOMMU, and vID of a nested Intel VT-d to a Context Table.
+ * @out_vdevice_id: Output virtual instance ID for the allocated object
+ * @__reserved2: Must be 0
+ *
+ * Allocate a virtual device instance (for a physical device) against a vIOMMU.
+ * This instance holds the device's information (related to its vIOMMU) in a 
VM.
+ */
+struct iommu_vdevice_alloc {
+   __u32 size;
+   __u32 viommu_id;
+   __u32 dev_id;
+   __u32 __reserved;
+   __aligned_u64 virt_id;
+   __u32 out_vdevice_id;
+   __u32 __reserved2;
+};
+#define IOMMU_VDEVICE_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VDEVICE_ALLOC)
 #endif
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index cbd0a80b2d67..9a8c3cbecc11 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -302,6 +302,7 @@ union ucmd_buffer {
struct iommu_option option;
struct iommu_vfio_ioas vfio_ioas;
struct iommu_viommu_alloc viommu;
+   struct iommu_vdevice_alloc vdev;
 #ifdef CONFIG_IOMMUFD_TEST
struct iommu_test_cmd test;
 #endif
@@ -355,6 +356,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 __reserved),
IOCTL_OP(IOMMU_VIOMMU_ALLOC, iommufd_viommu_alloc_ioctl,
 struct iommu_viommu_alloc, out_viommu_id),
+   IOCTL_OP(IOMMU_VDEVICE_ALLOC, iommufd_vdevice_alloc_ioctl,
+struct iommu_vdevice_alloc, __reserved2),
 #ifdef CONFIG_IOMMUFD_TEST
IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
 #endif
@@ -