From: Jack Thomson jackabt@amazon.com
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