[5/9] vfio: Pass in a struct vfio_device * to vfio_dma_rw()

Commit Message

Jason Gunthorpe April 12, 2022, 3:53 p.m. UTC

Every caller has a readily available vfio_device pointer, use that instead
of passing in a generic struct device. The struct vfio_device already
contains the group we need so this avoids complexity, extra refcountings,
and a confusing lifecycle model.

Signed-off-by: Jason Gunthorpe <[e-mail]>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c |  5 +++--
 drivers/vfio/vfio.c              | 22 ++++++++++------------
 include/linux/vfio.h             |  2 +-
 3 files changed, 14 insertions(+), 15 deletions(-)

Comments

Jason Gunthorpe April 13, 2022, 1:39 p.m. UTC | #1

On Wed, Apr 13, 2022 at 08:00:08AM +0200, Christoph Hellwig wrote:
> This looks good execept the extern nitpick:
> 
> Reviewed-by: Christoph Hellwig <[e-mail]>
> 
> However I'd move this before the previous patch.  More of the explanation
> there.

Yes, that looks good, done

Thanks,
Jason

Patch

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index df7d87409e3a9c..3302d5d4d92146 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -2184,8 +2184,9 @@  static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
 
 	info = (struct kvmgt_guest_info *)handle;
 
-	return vfio_dma_rw(kvmgt_vdev(info->vgpu)->vfio_group,
-			   gpa, buf, len, write);
+	return vfio_dma_rw(
+		mdev_legacy_get_vfio_device(kvmgt_vdev(info->vgpu)->mdev),
+		gpa, buf, len, write);
 }
 
 static int kvmgt_read_gpa(unsigned long handle, unsigned long gpa,
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 24b92a45cfc8f1..e6e102e017623b 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2323,32 +2323,28 @@  EXPORT_SYMBOL(vfio_group_unpin_pages);
  * As the read/write of user space memory is conducted via the CPUs and is
  * not a real device DMA, it is not necessary to pin the user space memory.
  *
- * The caller needs to call vfio_group_get_external_user() or
- * vfio_group_get_external_user_from_dev() prior to calling this interface,
- * so as to prevent the VFIO group from disposal in the middle of the call.
- * But it can keep the reference to the VFIO group for several calls into
- * this interface.
- * After finishing using of the VFIO group, the caller needs to release the
- * VFIO group by calling vfio_group_put_external_user().
- *
- * @group [in]		: VFIO group
+ * @vdev [in]		: VFIO device
  * @user_iova [in]	: base IOVA of a user space buffer
  * @data [in]		: pointer to kernel buffer
  * @len [in]		: kernel buffer length
  * @write		: indicate read or write
  * Return error code on failure or 0 on success.
  */
-int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
+int vfio_dma_rw(struct vfio_device *vdev, dma_addr_t user_iova,
 		void *data, size_t len, bool write)
 {
 	struct vfio_container *container;
 	struct vfio_iommu_driver *driver;
 	int ret = 0;
 
-	if (!group || !data || len <= 0)
+	if (!data || len <= 0)
 		return -EINVAL;
 
-	container = group->container;
+	ret = vfio_group_add_container_user(vdev->group);
+	if (ret)
+		return ret;
+
+	container = vdev->group->container;
 	driver = container->iommu_driver;
 
 	if (likely(driver && driver->ops->dma_rw))
@@ -2357,6 +2353,8 @@  int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
 	else
 		ret = -ENOTTY;
 
+	vfio_group_try_dissolve_container(vdev->group);
+
 	return ret;
 }
 EXPORT_SYMBOL(vfio_dma_rw);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 8f2a09801a660b..91d46e532ca104 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -161,7 +161,7 @@  extern int vfio_group_pin_pages(struct vfio_group *group,
 extern int vfio_group_unpin_pages(struct vfio_group *group,
 				  unsigned long *user_iova_pfn, int npage);
 
-extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
+extern int vfio_dma_rw(struct vfio_device *vdev, dma_addr_t user_iova,
 		       void *data, size_t len, bool write);
 
 extern struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group);