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Mon, 13 Oct 2025 08:15:29 -0700 (PDT) Received: from f4d4888f22f2.ant.amazon.com.com ([15.248.3.91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fab36a773sm135545825e9.0.2025.10.13.08.15.28 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 13 Oct 2025 08:15:28 -0700 (PDT) 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, roypat@amazon.co.uk, kalyazin@amazon.co.uk, jackabt@amazon.com Subject: [PATCH v2 0/4] KVM ARM64 pre_fault_memory Date: Mon, 13 Oct 2025 16:14:57 +0100 Message-ID: <20251013151502.6679-1-jackabt.amazon@gmail.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 fixes an issue with unaligned mmap allocations in the selftests. - The third 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. === Changes Since v1 [2] === Addressing feedback from Oliver: - No pre-fault flag is passed to user_mem_abort() or gmem_abort() now aborts are synthesized. - Remove retry loop from kvm_arch_vcpu_pre_fault_memory() [1]: https://lore.kernel.org/kvm/20240710174031.312055-1-pbonzini@redhat.com [2]: https://lore.kernel.org/all/20250911134648.58945-1-jackabt.amazon@gmail.com Jack Thomson (4): KVM: arm64: Add pre_fault_memory implementation KVM: selftests: Fix unaligned mmap allocations 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 | 73 +++++++++++- tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 12 +- .../selftests/kvm/pre_fault_memory_test.c | 110 +++++++++++++----- 7 files changed, 163 insertions(+), 38 deletions(-) base-commit: 42188667be387867d2bf763d028654cbad046f7b -- 2.43.0