vfio/pci: Clean up DMABUFs before disabling function

On device shutdown, make vfio_pci_core_close_device() call
vfio_pci_dma_buf_cleanup() before the function is disabled via
vfio_pci_core_disable().  This ensures that all access via DMABUFs is
revoked before the function's BARs become inaccessible.

This fixes an issue where, if the function is disabled first, a tiny
window exists in which the function's MSE is cleared and yet BARs
could still be accessed via the DMABUF.  The resources would also be
freed and up for grabs by a different driver.

Fixes: 5d74781ebc86c ("vfio/pci: Add dma-buf export support for MMIO regions")
Signed-off-by: Matt Evans <mattev@meta.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20260415181752.1027604-1-mattev@meta.com
Signed-off-by: Alex Williamson <alex@shazbot.org>

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index ad52abc46c04df935a779d66bbe91767eab66ed7..3f8d093aacf8a02e7bb1314d209f1e6f9b33100c 100644 (file)
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -734,10 +734,10 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 #if IS_ENABLED(CONFIG_EEH)
        eeh_dev_release(vdev->pdev);
 #endif
-       vfio_pci_core_disable(vdev);
-
        vfio_pci_dma_buf_cleanup(vdev);
 
+       vfio_pci_core_disable(vdev);
+
        mutex_lock(&vdev->igate);
        vfio_pci_eventfd_replace_locked(vdev, &vdev->err_trigger, NULL);
        vfio_pci_eventfd_replace_locked(vdev, &vdev->req_trigger, NULL);