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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-89f24ecbc11sm1141931785a.24.2025.10.29.13.44.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Oct 2025 13:44:12 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vED1g-000000053O5-0MFV; Wed, 29 Oct 2025 17:44:12 -0300 Date: Wed, 29 Oct 2025 17:44:12 -0300 From: Jason Gunthorpe To: Mukesh R Cc: alex.williamson@redhat.com, joe@perches.com, kvm@vger.kernel.org, "linux-kernel@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , "wei.liu@kernel.org" Subject: Re: [RFC] Making vma_to_pfn() public (due to vm_pgoff change) Message-ID: <20251029204412.GU760669@ziepe.ca> References: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Oct 27, 2025 at 02:21:56PM -0700, Mukesh R wrote: > Hi Alex, > > This regards vfio passthru support on hyperv running linux as dom0 aka > root. At a high level, cloud hypervisor uses vfio for set up as usual, > then maps the mmio ranges via the hyperv linux driver ioctls. > > Over a year ago, when working on this I had used vm_pgoff to get the pfn > for the mmio, that was 5.15 and early 6.x kernels. Now that I am porting > to 6.18 for upstreaming, I noticed: > > commit aac6db75a9fc > Author: Alex Williamson > vfio/pci: Use unmap_mapping_range() > > changed the behavior and vm_pgoff is no longer holding the pfn. In light > of that, I wondered if the following minor change, making vma_to_pfn() > public (after renaming it), would be acceptable to you. No way, no driver should be looking into VMAs like this - it is already a known security problem. Is this "hyperv linux driver ioctls" upstream? You should probably be looking to use the coming DMABUF stuff instead. Jason