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Tue, 13 Jan 2026 07:27:31 -0800 (PST) Received: from f4d4888f22f2.ant.amazon.com.com ([15.248.2.27]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d7f68f4ddsm421025325e9.2.2026.01.13.07.27.29 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 13 Jan 2026 07:27:30 -0800 (PST) From: Jack Thomson To: maz@kernel.org, oliver.upton@linux.dev, pbonzini@redhat.com Cc: joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, shuah@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, isaku.yamahata@intel.com, xmarcalx@amazon.co.uk, kalyazin@amazon.co.uk, jackabt@amazon.com Subject: [PATCH v4 0/3] KVM ARM64 pre_fault_memory Date: Tue, 13 Jan 2026 15:26:39 +0000 Message-ID: <20260113152643.18858-1-jackabt.amazon@gmail.com> X-Mailer: git-send-email 2.50.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260113_072733_989542_9BADB965 X-CRM114-Status: GOOD ( 14.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Jack Thomson This patch series adds ARM64 support for the KVM_PRE_FAULT_MEMORY feature, which was previously only available on x86 [1]. This allows us to reduce the number of stage-2 faults during execution. This is of benefit in post-copy migration scenarios, particularly in memory intensive applications, where we are experiencing high latencies due to the stage-2 faults. Patch Overview: - The first patch adds support for the KVM_PRE_FAULT_MEMORY ioctl on arm64. - The second patch updates the pre_fault_memory_test to support arm64. - The last patch extends the pre_fault_memory_test to cover different vm memory backings. With regards to the additional parameter to `user_mem_abort`, noted in the v3 review, would you like this to be fixed in this series or would a follow-up series be ok? I also found a series from Sean which looks to address this [2]. === Changes Since v3 [3] === - Updated to now return -EOPNOTSUPP for pKVM. Previously this was not checked. - When running a nested guest, properly resolve the L2 IPA to L1 IPA before pre faulting. - Refactoring, page_size is now unsigned and ordered definitions at top of pre_fault function. Thanks Marc for your review === Changes Since v2 [4] === - Update fault info synthesize value. Thanks Suzuki - Remove change to selftests for unaligned mmap allocations. Thanks Sean [1]: https://lore.kernel.org/kvm/20240710174031.312055-1-pbonzini@redhat.com [2]: https://lore.kernel.org/linux-arm-kernel/20250821210042.3451147-1-seanjc@google.com/ [3]: https://lore.kernel.org/linux-arm-kernel/20251119154910.97716-1-jackabt.amazon@gmail.com [4]: https://lore.kernel.org/linux-arm-kernel/20251013151502.6679-1-jackabt.amazon@gmail.com Jack Thomson (3): KVM: arm64: Add pre_fault_memory implementation KVM: selftests: Enable pre_fault_memory_test for arm64 KVM: selftests: Add option for different backing in pre-fault tests Documentation/virt/kvm/api.rst | 3 +- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/mmu.c | 79 +++++++++++- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/pre_fault_memory_test.c | 115 ++++++++++++++---- 6 files changed, 169 insertions(+), 31 deletions(-) base-commit: 3611ca7c12b740e250d83f8bbe3554b740c503b0 -- 2.43.0