On Fri, Nov 19, 2021 at 8:51 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > Overhaul TDP MMU's handling of zapping and TLB flushing to reduce the > number of TLB flushes, and to clean up the zapping code. The final patch > realizes the biggest change, which is to use RCU to defer any TLB flush > due to zapping a SP to the caller. The largest cleanup is to separate the > flows for zapping roots (zap _everything_), zapping leaf SPTEs (zap guest > mappings for whatever reason), and zapping a specific SP (NX recovery). > They're currently smushed into a single zap_gfn_range(), which was a good > idea at the time, but became a mess when trying to handle the different > rules, e.g. TLB flushes aren't needed when zapping a root because KVM can > safely zap a root if and only if it's unreachable. > > For booting an 8 vCPU, remote_tlb_flush (requests) goes from roughly > 180 (600) to 130 (215). > > Please don't apply patches 02 and 03, they've been posted elsehwere and by > other people. I included them here because some of the patches have > pseudo-dependencies on their changes. Patch 01 is also posted separately. > I had a brain fart and sent it out realizing that doing so would lead to > oddities. What's the base commit for this series? > > Hou Wenlong (1): > KVM: x86/mmu: Skip tlb flush if it has been done in zap_gfn_range() > > Sean Christopherson (27): > KVM: x86/mmu: Use yield-safe TDP MMU root iter in MMU notifier > unmapping > KVM: x86/mmu: Remove spurious TLB flushes in TDP MMU zap collapsible > path > KVM: x86/mmu: Retry page fault if root is invalidated by memslot > update > KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP > MMU > KVM: x86/mmu: Formalize TDP MMU's (unintended?) deferred TLB flush > logic > KVM: x86/mmu: Document that zapping invalidated roots doesn't need to > flush > KVM: x86/mmu: Drop unused @kvm param from kvm_tdp_mmu_get_root() > KVM: x86/mmu: Require mmu_lock be held for write in unyielding root > iter > KVM: x86/mmu: Allow yielding when zapping GFNs for defunct TDP MMU > root > KVM: x86/mmu: Check for !leaf=>leaf, not PFN change, in TDP MMU SP > removal > KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier > change_spte > KVM: x86/mmu: Drop RCU after processing each root in MMU notifier > hooks > KVM: x86/mmu: Add helpers to read/write TDP MMU SPTEs and document RCU > KVM: x86/mmu: Take TDP MMU roots off list when invalidating all roots > KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path > KVM: x86/mmu: Terminate yield-friendly walk if invalid root observed > KVM: x86/mmu: Refactor low-level TDP MMU set SPTE helper to take raw > vals > KVM: x86/mmu: Zap only the target TDP MMU shadow page in NX recovery > KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap > hook > KVM: x86/mmu: Add TDP MMU helper to zap a root > KVM: x86/mmu: Skip remote TLB flush when zapping all of TDP MMU > KVM: x86/mmu: Use "zap root" path for "slow" zap of all TDP MMU SPTEs > KVM: x86/mmu: Add dedicated helper to zap TDP MMU root shadow page > KVM: x86/mmu: Require mmu_lock be held for write to zap TDP MMU range > KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range() > KVM: x86/mmu: Do remote TLB flush before dropping RCU in TDP MMU > resched > KVM: x86/mmu: Defer TLB flush to caller when freeing TDP MMU shadow > pages > > arch/x86/kvm/mmu/mmu.c | 74 +++-- > arch/x86/kvm/mmu/mmu_internal.h | 7 +- > arch/x86/kvm/mmu/paging_tmpl.h | 3 +- > arch/x86/kvm/mmu/tdp_iter.c | 6 +- > arch/x86/kvm/mmu/tdp_iter.h | 15 +- > arch/x86/kvm/mmu/tdp_mmu.c | 526 +++++++++++++++++++------------- > arch/x86/kvm/mmu/tdp_mmu.h | 48 +-- > 7 files changed, 406 insertions(+), 273 deletions(-) > > -- > 2.34.0.rc2.393.gf8c9666880-goog >
