Currently disabling dirty logging with the TDP MMU is extremely slow. On a 96 vCPU / 96G VM it takes ~45 seconds to disable dirty logging with the TDP MMU, as opposed to ~3.5 seconds with the legacy MMU. This series optimizes TLB flushes and introduces in-place large page promotion, to bring the disable dirty log time down to ~2 seconds. Testing: Ran KVM selftests and kvm-unit-tests on an Intel Skylake. This series introduced no new failures. Performance: To collect these results I needed to apply Mingwei's patch "selftests: KVM: align guest physical memory base address to 1GB" https://lkml.org/lkml/2021/8/29/310 David Matlack is going to send out an updated version of that patch soon. Without this series, TDP MMU: > ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb Test iterations: 2 Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages guest physical test memory offset: 0x3fe7c0000000 Populate memory time: 10.966500447s Enabling dirty logging time: 0.002068737s Iteration 1 dirty memory time: 0.047556280s Iteration 1 get dirty log time: 0.001253914s Iteration 1 clear dirty log time: 0.049716661s Iteration 2 dirty memory time: 3.679662016s Iteration 2 get dirty log time: 0.000659546s Iteration 2 clear dirty log time: 1.834329322s Disabling dirty logging time: 45.738439510s Get dirty log over 2 iterations took 0.001913460s. (Avg 0.000956730s/iteration) Clear dirty log over 2 iterations took 1.884045983s. (Avg 0.942022991s/iteration) Without this series, Legacy MMU: > ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb Test iterations: 2 Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages guest physical test memory offset: 0x3fe7c0000000 Populate memory time: 12.664750666s Enabling dirty logging time: 0.002025510s Iteration 1 dirty memory time: 0.046240875s Iteration 1 get dirty log time: 0.001864342s Iteration 1 clear dirty log time: 0.170243637s Iteration 2 dirty memory time: 31.571088701s Iteration 2 get dirty log time: 0.000626245s Iteration 2 clear dirty log time: 1.294817729s Disabling dirty logging time: 3.566831573s Get dirty log over 2 iterations took 0.002490587s. (Avg 0.001245293s/iteration) Clear dirty log over 2 iterations took 1.465061366s. (Avg 0.732530683s/iteration) With this series, TDP MMU: > ./dirty_log_perf_test -v 96 -s anonymous_hugetlb_1gb Test iterations: 2 Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages guest physical test memory offset: 0x3fe7c0000000 Populate memory time: 12.016653537s Enabling dirty logging time: 0.001992860s Iteration 1 dirty memory time: 0.046701599s Iteration 1 get dirty log time: 0.001214806s Iteration 1 clear dirty log time: 0.049519923s Iteration 2 dirty memory time: 3.581931268s Iteration 2 get dirty log time: 0.000621383s Iteration 2 clear dirty log time: 1.894597059s Disabling dirty logging time: 1.950542092s Get dirty log over 2 iterations took 0.001836189s. (Avg 0.000918094s/iteration) Clear dirty log over 2 iterations took 1.944116982s. (Avg 0.972058491s/iteration) Patch breakdown: Patch 1 is a fix for a bug in the way the TBP MMU issues TLB flushes Patches 2-5 eliminate many unnecessary TLB flushes through better batching Patches 6-12 remove the need for a vCPU pointer to make_spte Patches 13-18 are small refactors in perparation for patch 19 Patch 19 implements in-place largepage promotion when disabling dirty logging Ben Gardon (19): KVM: x86/mmu: Fix TLB flush range when handling disconnected pt KVM: x86/mmu: Batch TLB flushes for a single zap KVM: x86/mmu: Factor flush and free up when zapping under MMU write lock KVM: x86/mmu: Yield while processing disconnected_sps KVM: x86/mmu: Remove redundant flushes when disabling dirty logging KVM: x86/mmu: Introduce vcpu_make_spte KVM: x86/mmu: Factor wrprot for nested PML out of make_spte KVM: x86/mmu: Factor mt_mask out of make_spte KVM: x86/mmu: Remove need for a vcpu from kvm_slot_page_track_is_active KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync_pages KVM: x86/mmu: Factor shadow_zero_check out of make_spte KVM: x86/mmu: Replace vcpu argument with kvm pointer in make_spte KVM: x86/mmu: Factor out the meat of reset_tdp_shadow_zero_bits_mask KVM: x86/mmu: Propagate memslot const qualifier KVM: x86/MMU: Refactor vmx_get_mt_mask KVM: x86/mmu: Factor out part of vmx_get_mt_mask which does not depend on vcpu KVM: x86/mmu: Add try_get_mt_mask to x86_ops KVM: x86/mmu: Make kvm_is_mmio_pfn usable outside of spte.c KVM: x86/mmu: Promote pages in-place when disabling dirty logging arch/x86/include/asm/kvm-x86-ops.h | 1 + arch/x86/include/asm/kvm_host.h | 2 + arch/x86/include/asm/kvm_page_track.h | 6 +- arch/x86/kvm/mmu/mmu.c | 45 +++--- arch/x86/kvm/mmu/mmu_internal.h | 6 +- arch/x86/kvm/mmu/page_track.c | 8 +- arch/x86/kvm/mmu/paging_tmpl.h | 6 +- arch/x86/kvm/mmu/spte.c | 43 +++-- arch/x86/kvm/mmu/spte.h | 17 +- arch/x86/kvm/mmu/tdp_mmu.c | 217 +++++++++++++++++++++----- arch/x86/kvm/mmu/tdp_mmu.h | 5 +- arch/x86/kvm/svm/svm.c | 8 + arch/x86/kvm/vmx/vmx.c | 40 +++-- include/linux/kvm_host.h | 10 +- virt/kvm/kvm_main.c | 12 +- 15 files changed, 302 insertions(+), 124 deletions(-) -- 2.34.0.rc0.344.g81b53c2807-goog
