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

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Message-ID: <20251102101158.6d2c36c6@shazbot.org>
Date: Sun, 2 Nov 2025 10:11:58 -0700
From: Alex Williamson <alex@...zbot.org>
To: Leon Romanovsky <leon@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
 Logan Gunthorpe <logang@...tatee.com>, Jens Axboe <axboe@...nel.dk>,
 Robin Murphy <robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>,
 Marek Szyprowski <m.szyprowski@...sung.com>,
 Jason Gunthorpe <jgg@...pe.ca>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Jonathan Corbet <corbet@....net>, Sumit Semwal <sumit.semwal@...aro.org>,
 Christian König <christian.koenig@....com>,
 Alex Williamson <alex.williamson@...hat.com>,
 Kees Cook <kees@...nel.org>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Ankit Agrawal <ankita@...dia.com>, Yishai Hadas <yishaih@...dia.com>,
 Shameer Kolothum <skolothumtho@...dia.com>,
 Kevin Tian <kevin.tian@...el.com>, Krishnakant Jaju <kjaju@...dia.com>,
 Matt Ochs <mochs@...dia.com>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
 iommu@...ts.linux.dev, linux-mm@...ck.org, linux-doc@...r.kernel.org,
 linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linaro-mm-sig@...ts.linaro.org, kvm@...r.kernel.org,
 linux-hardening@...r.kernel.org,
 Vivek Kasireddy <vivek.kasireddy@...el.com>
Subject: Re: [PATCH v6 10/11] vfio/pci: Add dma-buf export support for MMIO
 regions

On Sun, 2 Nov 2025 17:12:53 +0200
Leon Romanovsky <leon@...nel.org> wrote:
> On Sun, Nov 02, 2025 at 08:01:37AM -0700, Alex Williamson wrote: 
> > 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.

Let's hold off, if this ends up being the only fixup I can roll it in.
Thanks,

Alex

> 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
> >   
>