From: Jason Gunthorpe <[email protected]> Simple conversion to add a match_mapping() callback that offers an exporter SGT mapping type. Later patches will add a physical address exporter so go straight to adding the match_mapping() function.
The check for attachment->peer2peer is replaced with setting exporter_requires_p2p=true. VFIO always uses MMIO memory. Signed-off-by: Jason Gunthorpe <[email protected]> [ dma_buf_mapping_attach() calls ->match_mapping() without holding the dma_resv lock, so the dma_resv_assert_held() in vfio_pci_dma_buf_match_mapping() fires under lockdep and the priv->vdev read it guarded was not serialised against vfio_pci_dma_buf_cleanup() either. Fixed as Jason proposed in https://lore.kernel.org/all/[email protected]/: hold a pci_dev reference for the lifetime of the dmabuf and use it for the P2P match instead of dereferencing priv->vdev. - apopple ] Reported-by: Baolu Lu <[email protected]> Closes: https://lore.kernel.org/all/[email protected]/ Signed-off-by: Alistair Popple <[email protected]> --- drivers/vfio/pci/vfio_pci_dmabuf.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index c16f460c01d6..58e771309c5f 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -12,6 +12,7 @@ MODULE_IMPORT_NS("DMA_BUF"); struct vfio_pci_dma_buf { struct dma_buf *dmabuf; struct vfio_pci_core_device *vdev; + struct pci_dev *pdev; struct list_head dmabufs_elm; size_t size; struct phys_vec *phys_vec; @@ -27,9 +28,6 @@ static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf, { struct vfio_pci_dma_buf *priv = dmabuf->priv; - if (!attachment->peer2peer) - return -EOPNOTSUPP; - if (priv->revoked) return -ENODEV; @@ -95,15 +93,31 @@ static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf) up_write(&priv->vdev->memory_lock); vfio_device_put_registration(&priv->vdev->vdev); } + pci_dev_put(priv->pdev); kfree(priv->phys_vec); kfree(priv); } -static const struct dma_buf_ops vfio_pci_dmabuf_ops = { - .attach = vfio_pci_dma_buf_attach, +static const struct dma_buf_mapping_sgt_exp_ops vfio_pci_dma_buf_sgt_ops = { .map_dma_buf = vfio_pci_dma_buf_map, .unmap_dma_buf = vfio_pci_dma_buf_unmap, +}; + +static int vfio_pci_dma_buf_match_mapping(struct dma_buf_match_args *args) +{ + struct vfio_pci_dma_buf *priv = args->dmabuf->priv; + struct dma_buf_mapping_match sgt_match[1]; + + sgt_match[0] = DMA_BUF_EMAPPING_SGT_P2P(&vfio_pci_dma_buf_sgt_ops, + priv->pdev); + + return dma_buf_match_mapping(args, sgt_match, ARRAY_SIZE(sgt_match)); +} + +static const struct dma_buf_ops vfio_pci_dmabuf_ops = { + .attach = vfio_pci_dma_buf_attach, .release = vfio_pci_dma_buf_release, + .match_mapping = vfio_pci_dma_buf_match_mapping, }; /* @@ -300,6 +314,7 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, goto err_dev_put; } + priv->pdev = pci_dev_get(vdev->pdev); kref_init(&priv->kref); init_completion(&priv->comp); -- 2.54.0
