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vfio: Wait for dma-buf invalidation to complete

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dma-buf invalidation is handled asynchronously by the hardware, so VFIO
must wait until all affected objects have been fully invalidated.

In addition, the dma-buf exporter is expecting that all importers unmap any
buffers they previously mapped.

Fixes: 5d74781ebc ("vfio/pci: Add dma-buf export support for MMIO regions")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex@shazbot.org>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20260131-dmabuf-revoke-v7-4-463d956bd527@nvidia.com
This commit is contained in:
Leon Romanovsky 2026-01-31 07:34:14 +02:00 committed by Christian König
parent a408c0ca0c
commit 1a8a5227f2
1 changed files with 57 additions and 4 deletions
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61
drivers/vfio/pci/vfio_pci_dmabuf.c
View File

@ -17,6 +17,8 @@ struct vfio_pci_dma_buf {
struct phys_vec *phys_vec;
struct p2pdma_provider *provider;
u32 nr_ranges;
struct kref kref;
struct completion comp;
u8 revoked : 1;
};
@ -44,27 +46,46 @@ static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf,
return 0;
}
static void vfio_pci_dma_buf_done(struct kref *kref)
{
struct vfio_pci_dma_buf *priv =
container_of(kref, struct vfio_pci_dma_buf, kref);
complete(&priv->comp);
}
static struct sg_table *
vfio_pci_dma_buf_map(struct dma_buf_attachment *attachment,
enum dma_data_direction dir)
{
struct vfio_pci_dma_buf *priv = attachment->dmabuf->priv;
struct sg_table *ret;
dma_resv_assert_held(priv->dmabuf->resv);
if (priv->revoked)
return ERR_PTR(-ENODEV);
return dma_buf_phys_vec_to_sgt(attachment, priv->provider,
priv->phys_vec, priv->nr_ranges,
priv->size, dir);
ret = dma_buf_phys_vec_to_sgt(attachment, priv->provider,
priv->phys_vec, priv->nr_ranges,
priv->size, dir);
if (IS_ERR(ret))
return ret;
kref_get(&priv->kref);
return ret;
}
static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment,
struct sg_table *sgt,
enum dma_data_direction dir)
{
struct vfio_pci_dma_buf *priv = attachment->dmabuf->priv;
dma_resv_assert_held(priv->dmabuf->resv);
dma_buf_free_sgt(attachment, sgt, dir);
kref_put(&priv->kref, vfio_pci_dma_buf_done);
}
static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf)
@ -286,6 +307,9 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags,
goto err_dev_put;
}
kref_init(&priv->kref);
init_completion(&priv->comp);
/* dma_buf_put() now frees priv */
INIT_LIST_HEAD(&priv->dmabufs_elm);
down_write(&vdev->memory_lock);
@ -330,9 +354,33 @@ void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked)
if (priv->revoked != revoked) {
dma_resv_lock(priv->dmabuf->resv, NULL);
priv->revoked = revoked;
if (revoked)
priv->revoked = true;
dma_buf_invalidate_mappings(priv->dmabuf);
dma_resv_wait_timeout(priv->dmabuf->resv,
DMA_RESV_USAGE_BOOKKEEP, false,
MAX_SCHEDULE_TIMEOUT);
dma_resv_unlock(priv->dmabuf->resv);
if (revoked) {
kref_put(&priv->kref, vfio_pci_dma_buf_done);
wait_for_completion(&priv->comp);
} else {
/*
* Kref is initialize again, because when revoke
* was performed the reference counter was decreased
* to zero to trigger completion.
*/
kref_init(&priv->kref);
/*
* There is no need to wait as no mapping was
* performed when the previous status was
* priv->revoked == true.
*/
reinit_completion(&priv->comp);
dma_resv_lock(priv->dmabuf->resv, NULL);
priv->revoked = false;
dma_resv_unlock(priv->dmabuf->resv);
}
}
fput(priv->dmabuf->file);
}
@ -353,7 +401,12 @@ void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev)
priv->vdev = NULL;
priv->revoked = true;
dma_buf_invalidate_mappings(priv->dmabuf);
dma_resv_wait_timeout(priv->dmabuf->resv,
DMA_RESV_USAGE_BOOKKEEP, false,
MAX_SCHEDULE_TIMEOUT);
dma_resv_unlock(priv->dmabuf->resv);
kref_put(&priv->kref, vfio_pci_dma_buf_done);
wait_for_completion(&priv->comp);
vfio_device_put_registration(&vdev->vdev);
fput(priv->dmabuf->file);
}