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

[Leon Romanovsky <leon@kernel.org>]

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
>