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[54.240.197.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3d40c182sm1118217f8f.34.2026.10.23.10.42.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Oct 2026 10:42:20 -0700 (PDT) From: Fred Griffoul To: Ackerley Tng Cc: Alex Williamson , Alexander Graf , Alexander Viro , Alexey Kardashevskiy , Andrew Morton , "Aneesh Kumar K.V" , Ashish Kalra , Baolin Wang , Baolu Lu , Bill Wendling , Borislav Petkov , Catalin Marinas , Christian Brauner , =?utf-8?q?Christian_K=C3=B6nig?= , Connor Williamson , Dave Hansen , Dave Jiang , David Hildenbrand , David Rientjes , David Woodhouse , Erdem Aktas , Frank van der Linden , Gregory Price , "H. Peter Anvin" , Hugh Dickins , Ingo Molnar , Jacob Pan , James Houghton , Jan Kara , Jason Gunthorpe , Jianxiong Gao , Joerg Roedel , Joey Gouly , John Starks , Jonathan Corbet , Justin Stitt , Kevin Tian , Lorenzo Stoakes , Marc Zyngier , Michael Roth , Mike Rapoport , Nathan Chancellor , Nick Desaulniers , Nicolin Chen , Oliver Upton , Paolo Bonzini , Pratyush Yadav , Randy Dunlap , Robin Murphy , Samiullah Khawaja , Sean Christopherson , Shuah Khan , Steffen Eiden , Steven Price , Suzuki K Poulose , Tarun Sahu , Thomas Gleixner , Tom Lendacky , Tycho Andersen , Vishal Annapurve , Vlastimil Babka , Will Deacon , Xu Yilun , Yan Zhao , Zenghui Yu , x86@kernel.org, Shuah Khan , Fuad Tabba , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev Subject: Re: [PATCH RFC v2 31/50] KVM: guest_memfd: Support getting PFNs for stage 2 from providers Date: Fri, 23 Oct 2026 17:42:18 +0000 Message-ID: <20261023174218.54790-1-griffoul@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> References: <20261022-gmem-alternative-providers-v2-0-5dd1dc6c660a@google.com> <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > + if (kvm_gmem_is_pfn_mode(gi)) { > + r = gmem_provider_get_pfn(gi, index, pfn, max_order); > + if (r) > + return ERR_PTR(r); > + return NULL; > + } The order goes from the provider to the fault handler unchecked. MPS reports 0, but a provider with contiguous memory won't, and then a fault can map a block that the gfn and pfn aren't aligned to, one that mixes shared and private pages, or one that covers a page being revoked or converted at the same time: only that page's gfn is marked as being invalidated, so the fault doesn't retry. Clamping the order in kvm_gmem_get_pfn() to an aligned block of uniform attributes, and widening invalidations to the surrounding blocks, would cover it. Fred