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Thu, 11 Sep 2025 06:49:37 -0700 (PDT) Received: from f4d4888f22f2.ant.amazon.com.com ([15.248.2.27]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e760778915sm2608361f8f.12.2025.09.11.06.49.35 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 11 Sep 2025 06:49:36 -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 0/6] KVM ARM64 pre_fault_memory Date: Thu, 11 Sep 2025 14:46:42 +0100 Message-Id: <20250911134648.58945-1-jackabt.amazon@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) 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 Overview: This patch series adds ARM64 support for the KVM_PRE_FAULT_MEMORY feature, which was previously only available on x86 [1]. This allows a reduction in the number of stage-2 faults during execution. This is beneficial in post-copy migration scenarios, particularly in memory intensive applications, where high latencies are experienced due to the stage-2 faults when pre-populating memory via UFFD / memcpy. Patch Overview: - The first patch is a preparatory refactor. - The second patch is adding a page walk flag for pre-faulting. - The third patch adds support for the KVM_PRE_FAULT_MEMORY ioctl on arm64. - The fourth patch fixes an issue with unaligned mmap allocations in the selftests. - The fifth 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. [1]: https://lore.kernel.org/kvm/20240710174031.312055-1-pbonzini@redhat.com Jack Thomson (6): KVM: arm64: Add __gmem_abort and __user_mem_abort KVM: arm64: Add KVM_PGTABLE_WALK_PRE_FAULT walk flag 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 arch/arm64/include/asm/kvm_pgtable.h | 3 + arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/hyp/pgtable.c | 6 +- arch/arm64/kvm/mmu.c | 97 +++++++++++++-- tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 12 +- .../selftests/kvm/pre_fault_memory_test.c | 110 +++++++++++++----- 8 files changed, 186 insertions(+), 45 deletions(-) base-commit: 42188667be387867d2bf763d028654cbad046f7b -- 2.43.0