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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id u142sm3652118wmu.3.2021.02.09.01.19.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Feb 2021 01:19:34 -0800 (PST) Subject: Re: [PATCH 1/2] mm: provide a sane PTE walking API for modules To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, jgg@ziepe.ca, linux-mm@kvack.org, Andrew Morton , dan.j.williams@intel.com, Daniel Vetter References: <20210205103259.42866-1-pbonzini@redhat.com> <20210205103259.42866-2-pbonzini@redhat.com> <20210208173936.GA1496438@infradead.org> <3b10057c-e117-89fa-1bd4-23fb5a4efb5f@redhat.com> <20210209081408.GA1703597@infradead.org> From: Paolo Bonzini Message-ID: Date: Tue, 9 Feb 2021 10:19:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210209081408.GA1703597@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/02/21 09:14, Christoph Hellwig wrote: > On Mon, Feb 08, 2021 at 07:18:56PM +0100, Paolo Bonzini wrote: >> Fair enough. I would expect that pretty much everyone using follow_pfn will >> at least want to switch to this one (as it's less bad and not impossible to >> use correctly), but I'll squash this in: > > > Daniel looked into them, so he may correct me, but the other follow_pfn > users and their destiny are: > > - SGX, which is not modular and I think I just saw a patch to kill them > - v4l videobuf and frame vector: I think those are going away > entirely as they implement a rather broken pre-dmabuf P2P scheme > - vfio: should use MMU notifiers eventually Yes, I'm thinking mostly of vfio, which could use follow_pte as a short-term fix for just the missing permission check. There's also s390 PCI, which is also not modular. Paolo > Daniel, what happened to your follow_pfn series?