[PATCH] vfio/pci: Clean up DMABUFs before disabling function

[PATCH] vfio/pci: Clean up DMABUFs before disabling function

[Matt Evans]

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>
---

Jason,

Added your R-B from https://lore.kernel.org/kvm/20260330132952.GS310919@nvidia.com/

Thanks, Matt

drivers/vfio/pci/vfio_pci_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index ad52abc46c04..3f8d093aacf8 100644
--- 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);
-- 
2.47.3

Re: [PATCH] vfio/pci: Clean up DMABUFs before disabling function

[Leon Romanovsky]

On Wed, Apr 15, 2026 at 11:17:52AM -0700, Matt Evans wrote:
> 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>
> ---
> 
> Jason,
> 
> Added your R-B from https://lore.kernel.org/kvm/20260330132952.GS310919@nvidia.com/
> 
> Thanks, Matt
> 
> drivers/vfio/pci/vfio_pci_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>

RE: [PATCH] vfio/pci: Clean up DMABUFs before disabling function

[Tian, Kevin]

> From: Matt Evans <mattev@meta.com>
> Sent: Thursday, April 16, 2026 2:18 AM
> 
> 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>