linux-kernel - Re: [PATCH v2 3/3] vfio/type1: handle DMA map/unmap up to the addressable limit

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Message-ID: <aOcA8LhIoWZPNOA5@devgpu015.cco6.facebook.com>
Date: Wed, 8 Oct 2025 17:25:20 -0700
From: Alex Mastro <amastro@...com>
To: Alex Williamson <alex.williamson@...hat.com>
CC: Jason Gunthorpe <jgg@...pe.ca>,
        Alejandro Jimenez
	<alejandro.j.jimenez@...cle.com>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] vfio/type1: handle DMA map/unmap up to the
 addressable limit

On Tue, Oct 07, 2025 at 09:08:48PM -0700, Alex Mastro wrote:
> @@ -1401,17 +1409,17 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>  		if (dma && dma->iova != iova)
>  			goto unlock;
>  
> -		dma = vfio_find_dma(iommu, iova_end, 0);
> -		if (dma && dma->iova + dma->size != iova + size)
> +		dma = vfio_find_dma(iommu, iova_end, 1);
> +		if (dma && dma->iova + dma->size - 1 != iova_end)
>  			goto unlock;
>  	}
>  
>  	ret = 0;
> -	n = first_n = vfio_find_dma_first_node(iommu, iova, size);
> +	n = first_n = vfio_find_dma_first_node(iommu, iova, iova_end);

I missed updating iova_end to be consistent in the unmap_all case, which is
broken with this change. Currently, iova_end is only assigned by the
check_add_overflow call in the !unmap_all path. Will address in v3.