linux-kernel - Re: [PATCH v4 0/3] vfio: handle DMA map/unmap up to the addressable limit

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Message-ID: <3308406e-2e64-4d53-8bcc-bac84575c1d9@oracle.com>
Date: Wed, 15 Oct 2025 17:25:14 -0400
From: Alejandro Jimenez <alejandro.j.jimenez@...cle.com>
To: Alex Williamson <alex@...zbot.org>, Alex Mastro <amastro@...com>
Cc: Jason Gunthorpe <jgg@...pe.ca>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/3] vfio: handle DMA map/unmap up to the addressable
 limit

On 10/15/25 3:24 PM, Alex Williamson wrote:
> On Sun, 12 Oct 2025 22:32:23 -0700
> Alex Mastro <amastro@...com> wrote:
> 
>> This patch series aims to fix vfio_iommu_type.c to support
>> VFIO_IOMMU_MAP_DMA and VFIO_IOMMU_UNMAP_DMA operations targeting IOVA
>> ranges which lie against the addressable limit. i.e. ranges where
>> iova_start + iova_size would overflow to exactly zero.
> 
> The series looks good to me and passes my testing.  Any further reviews
> from anyone?  I think we should make this v6.18-rc material.  Thanks,
> 

I haven't had a chance yet to closely review the latest patchset 
versions, but I did test this v4 and confirmed that it solves the issue 
of not being able to unmap an IOVA range extending up to the address 
space boundary. I verified both with the simplified test case at:
https://gist.github.com/aljimenezb/f3338c9c2eda9b0a7bf5f76b40354db8

plus using QEMU's amd-iommu and a guest with iommu.passthrough=0 
iommu.forcedac=1 (which is how I first found the problem).

So Alex Mastro, please feel free to add:

Tested-by: Alejandro Jimenez <alejandro.j.jimenez@...cle.com>

for the series. I'll try to find time to review the patches in detail.

Thank you,
Alejandro

> Alex