[PATCH v2 4/7] vfio/mdev: Pass in a struct vfio_device * to vfio_dma_rw()

Jason Gunthorpe
2022-04-21T16:31:02Z

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.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/gpu/drm/i915/gvt/gvt.h | 4 ++--
drivers/vfio/vfio.c | 24 +++++++++++-------------
include/linux/vfio.h | 2 +-
3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index 03ecffc2ba56a9..5a28ee965b7f3e 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/drivers/gpu/drm/i915/gvt/gvt.h
@@ -732,7 +732,7 @@ static inline int intel_gvt_read_gpa(struct intel_vgpu *vgpu, unsigned long gpa,
{
if (!vgpu->attached)
return -ESRCH;
- return vfio_dma_rw(vgpu->vfio_group, gpa, buf, len, false);
+ return vfio_dma_rw(&vgpu->vfio_device, gpa, buf, len, false);
}

/**
@@ -750,7 +750,7 @@ static inline int intel_gvt_write_gpa(struct intel_vgpu *vgpu,
{
if (!vgpu->attached)
return -ESRCH;
- return vfio_dma_rw(vgpu->vfio_group, gpa, buf, len, true);
+ return vfio_dma_rw(&vgpu->vfio_device, gpa, buf, len, true);
}

void intel_gvt_debugfs_remove_vgpu(struct intel_vgpu *vgpu);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 24b92a45cfc8f1..d10d20d393b706 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,
- void *data, size_t len, bool write)
+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);
--
2.36.0