Hi,
This series is on top of kvmarm/next as I needed to also modify Eager page splitting logic in clear-dirty-log API. Eager page splitting is not present in Linux 6.4-rc4.
Also, I had to change selftests patches (1 to 5) as some commits were removed from kvm/queue remote. This caused issue due to different APIs being present in dirty_log_perf_test when I was rebasing v2. Those removed commits are now back in kvm-x86 branch of Sean [1] but not in kvmarm/next or kvm/queue. I didn't want to wait for review of v2, so I changed dirty_log_perf_test to work with kvmarm/next branch. When Sean's kvm-x86 branch is merged, sleftests in this patch series need to be modified to use new APIs or whoever merges last need to take care of that.
This patch series modifies clear-dirty-log operation to run under MMU read lock. It write protects SPTEs and split huge pages using MMU read lock instead of MMU write lock.
Use of MMU read lock is made possible by using shared page table walkers. Currently only page fault handlers use shared page table walkers, with this series, clear-dirty-log operation will also use shared page table walkers.
Patches 1 to 5: These patches are modifying dirty_log_perf_test. Intent is to mimic production scenarios where guest keeps on executing while userspace thread collects and clears dirty logs independently.
Three new command line options are added: 1. j: Allows to run guest vCPUs and main thread collecting dirty logs independently of each other after initialization is complete. 2. k: Allows to clear dirty logs in smaller chunks compared to existing whole memslot clear in one call. 3. l: Allows to add customizable wait time between consecutive clear dirty log calls to mimic sending dirty memory to destination.
Patch 7-16: These patches refactor code to move MMU lock operations to arch specific code, refactor Arm's page table walker APIs, and change MMU write lock for clearing dirty logs to read lock. Patch 16 has results showing improvements based on dirty_log_perf_test.
1. https://lore.kernel.org/lkml/168565341087.666819.6731422637224460050.b4-ty@g...
v2: - Fix compile warning for mips and riscv. - Added logic to continue or retry shared page walk which are not fault handler. - Huge page split also changed to run under MMU read lock. - Added more explanations in commit logs. - Selftests is modified because a commit series was reverted back in dirty_log_perf_test on kvm/queue.
v1: https://lore.kernel.org/lkml/20230421165305.804301-1-vipinsh@google.com/
Vipin Sharma (16): KVM: selftests: Clear dirty logs in user defined chunks sizes in dirty_log_perf_test KVM: selftests: Add optional delay between consecutive clear-dirty-log calls KVM: selftests: Pass the count of read and write accesses from guest to host KVM: selftests: Print read-write progress by vCPUs in dirty_log_perf_test KVM: selftests: Allow independent execution of vCPUs in dirty_log_perf_test KVM: arm64: Correct the kvm_pgtable_stage2_flush() documentation KVM: mmu: Move mmu lock/unlock to arch code for clear dirty log KMV: arm64: Pass page table walker flags to stage2_apply_range_*() KVM: arm64: Document the page table walker actions based on the callback's return value KVM: arm64: Return -ENOENT if PTE is not valid in stage2_attr_walker KVM: arm64: Use KVM_PGTABLE_WALK_SHARED flag instead of KVM_PGTABLE_WALK_HANDLE_FAULT KVM: arm64: Retry shared page table walks outside of fault handler KVM: arm64: Run clear-dirty-log under MMU read lock KVM: arm64: Pass page walker flags from callers of stage 2 split walker KVM: arm64: Provide option to pass page walker flag for huge page splits KVM: arm64: Split huge pages during clear-dirty-log under MMU read lock
arch/arm64/include/asm/kvm_pgtable.h | 42 +++-- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 4 +- arch/arm64/kvm/hyp/pgtable.c | 68 ++++++-- arch/arm64/kvm/mmu.c | 65 +++++--- arch/mips/kvm/mmu.c | 2 + arch/riscv/kvm/mmu.c | 2 + arch/x86/kvm/mmu/mmu.c | 3 + .../selftests/kvm/dirty_log_perf_test.c | 147 ++++++++++++++---- tools/testing/selftests/kvm/lib/memstress.c | 13 +- virt/kvm/dirty_ring.c | 2 - virt/kvm/kvm_main.c | 4 - 11 files changed, 265 insertions(+), 87 deletions(-)
base-commit: 532b2ecfa547f02b1825108711565eff026bce5a