linux-kernel - Re: [PATCH] vfio: Ignore -ENODEV when getting MSI cookie

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Date:   Wed, 1 Apr 2020 16:39:50 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Cornelia Huck <cohuck@...hat.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will@...nel.org>,
        Eric Auger <eric.auger@...hat.com>, kvm@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] vfio: Ignore -ENODEV when getting MSI cookie

On Wed,  1 Apr 2020 11:27:24 +0100
Andre Przywara <andre.przywara@....com> wrote:

> When we try to get an MSI cookie for a VFIO device, that can fail if
> CONFIG_IOMMU_DMA is not set. In this case iommu_get_msi_cookie() returns
> -ENODEV, and that should not be fatal.
> 
> Ignore that case and proceed with the initialisation.
> 
> This fixes VFIO with a platform device on the Calxeda Midway (no MSIs).
> 
> Fixes: f6810c15cf973f ("iommu/arm-smmu: Clean up early-probing workarounds")
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> Acked-by: Robin Murphy <robin.murphy@....com>
> Reviewed-by: Eric Auger <eric.auger@...hat.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 9fdfae1cb17a..85b32c325282 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1787,7 +1787,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  
>  	if (resv_msi) {
>  		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
> -		if (ret)
> +		if (ret && ret != -ENODEV)
>  			goto out_detach;
>  	}
>  

Applied to vfio next branch for v5.7.  Thanks,

Alex