Re: [PATCH v6 10/11] vfio/pci: Add dma-buf export support for MMIO regions

Leon Romanovsky
2025-11-02T15:13:00Z

On Sun, Nov 02, 2025 at 08:01:37AM -0700, Alex Williamson wrote:
> On Sun, 2 Nov 2025 10:00:58 +0200
> Leon Romanovsky <leon@kernel.org> wrote:
> > @@ -2391,6 +2403,7 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
> > struct iommufd_ctx *iommufd_ctx)
> > {
> > struct vfio_pci_core_device *vdev;
> > + bool restore_revoke = false;
> > struct pci_dev *pdev;
> > int ret;
> >
> > @@ -2459,6 +2472,8 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
> > break;
> > }
> >
> > + vfio_pci_dma_buf_move(vdev, true);
> > + restore_revoke = true;
> > vfio_pci_zap_bars(vdev);
> > }
> >
> > @@ -2486,6 +2501,12 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
> > struct vfio_pci_core_device, vdev.dev_set_list);
> >
> > err_undo:
> > + if (restore_revoke) {
> > + list_for_each_entry(vdev, &dev_set->device_list, vdev.dev_set_list)
> > + if (__vfio_pci_memory_enabled(vdev))
> > + vfio_pci_dma_buf_move(vdev, false);
> > + }
> > +
> > list_for_each_entry_from_reverse(vdev, &dev_set->device_list,
> > vdev.dev_set_list)
>
> We don't need the separate loop or flag, and adding it breaks the
> existing reverse list walk. Thanks,

Do you want me to send v7? I have a feeling that v6 is good to be merged.

Thanks

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 24204893e221..51a3bcc26f8b 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -2403,7 +2403,6 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
struct iommufd_ctx *iommufd_ctx)
{
struct vfio_pci_core_device *vdev;
- bool restore_revoke = false;
struct pci_dev *pdev;
int ret;

@@ -2473,7 +2472,6 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
}

vfio_pci_dma_buf_move(vdev, true);
- restore_revoke = true;
vfio_pci_zap_bars(vdev);
}

@@ -2501,15 +2499,12 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
struct vfio_pci_core_device, vdev.dev_set_list);

err_undo:
- if (restore_revoke) {
- list_for_each_entry(vdev, &dev_set->device_list, vdev.dev_set_list)
- if (__vfio_pci_memory_enabled(vdev))
- vfio_pci_dma_buf_move(vdev, false);
- }
-
list_for_each_entry_from_reverse(vdev, &dev_set->device_list,
- vdev.dev_set_list)
+ vdev.dev_set_list) {
+ if (__vfio_pci_memory_enabled(vdev))
+ vfio_pci_dma_buf_move(vdev, false);
up_write(&vdev->memory_lock);
+ }

list_for_each_entry(vdev, &dev_set->device_list, vdev.dev_set_list)
pm_runtime_put(&vdev->pdev->dev);

>
> Alex
>