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([2a01:e0a:f0e:9070:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2dc57c8dbbsm363629266b.12.2026.09.29.01.29.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Sep 2026 01:29:54 -0700 (PDT) Message-ID: Date: Tue, 29 Sep 2026 10:29:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: eric.auger@redhat.com Subject: Re: [PATCH 4/7] vfio/platform: keep logical vm_pgoff in MMIO region mmap Content-Language: en-US To: Alex Williamson , Abdifatah Suruur Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, smostafa@google.com, praan@google.com, ioana.ciornei@nxp.com, nipun.gupta@amd.com, nikhil.agarwal@amd.com References: <20260921122334.2099-1-suruurism@gmail.com> <20260921122334.2099-5-suruurism@gmail.com> <20260928170019.2b46ee5a@shazbot.org> From: Eric Auger In-Reply-To: <20260928170019.2b46ee5a@shazbot.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/29/26 1:00 AM, Alex Williamson wrote: > On Mon, 21 Sep 2026 15:23:31 +0300 > Abdifatah Suruur wrote: > >> vfio_platform_mmap_mmio() overwrites vma->vm_pgoff with the physical >> frame number of the MMIO region and passes it to remap_pfn_range(). >> The VMA is inserted into the device file's mapping->i_mmap interval >> tree keyed by vm_pgoff, which VFIO expects to be the logical file >> offset: the core links every device mmap to the device inode's >> i_mapping precisely so that unmap_mapping_range() can revoke all >> mappings associated with a device (see vfio_device_cdev_open()). >> >> With a raw PFN in vm_pgoff the interval tree entry lands in the wrong >> coordinate space and unmap_mapping_range() cannot find the VMA, >> leaving stale MMIO mappings behind any revocation attempt. Keep >> vm_pgoff in the logical VFIO offset space, as vfio-pci does, and pass >> the physical PFN to remap_pfn_range() explicitly. >> >> This is defensive hygiene: none of vfio-platform, vfio/fsl-mc and >> vfio/cdx call unmap_mapping_range() today, so no reachable >> stale-mapping issue exists. Keeping vm_pgoff logical preserves the >> VFIO core contract for any future revocation path. >> >> Signed-off-by: Abdifatah Suruur >> --- >> --- a/drivers/vfio/platform/vfio_platform_common.c >> +++ b/drivers/vfio/platform/vfio_platform_common.c >> @@ -561,6 +561,5 @@ >> vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); >> - vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff; >> - >> - return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, >> + return remap_pfn_range(vma, vma->vm_start, >> + (region.addr >> PAGE_SHIFT) + pgoff, >> req_len, vma->vm_page_prot); >> } > Eric had provided a Reviewed-by in [1], I think the only difference is > the commit log, including dropping the Fixes: tag since it's not > currently reachable. I'd keep the R-b for that, or he can re-add it on > the next spin. Thanks, I do agree. Feel free to keep the R-b Eric > > Alex > > [1]https://lore.kernel.org/all/21fda51a-6974-487d-874a-387dd73e2346@redhat.com/ >