Re: [PATCH v6 4/4] vfio: convey kvm that the vfio-pci device is wc safe

[Catalin Marinas <catalin.marinas@arm.com>]

+ David H

On Thu, Feb 08, 2024 at 02:16:52AM +0530, ankita@nvidia.com wrote:
> From: Ankit Agrawal <ankita@nvidia.com>
> 
> The code to map the MMIO in S2 as NormalNC is enabled when conveyed
> that the device is WC safe using a new flag VM_VFIO_ALLOW_WC.
> 
> Make vfio-pci set the VM_VFIO_ALLOW_WC flag.
> 
> This could be extended to other devices in the future once that
> is deemed safe.
> 
> Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Acked-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 1cbc990d42e0..c3f95ec7fc3a 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -1863,7 +1863,8 @@ int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma
>  	 * See remap_pfn_range(), called from vfio_pci_fault() but we can't
>  	 * change vm_flags within the fault handler.  Set them now.
>  	 */
> -	vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
> +	vm_flags_set(vma, VM_VFIO_ALLOW_WC | VM_IO | VM_PFNMAP |
> +			VM_DONTEXPAND | VM_DONTDUMP);
>  	vma->vm_ops = &vfio_pci_mmap_ops;
>  
>  	return 0;

Acked-by: Catalin Marinas <catalin.marinas@arm.com>