From 20d49186c0302015c229e23c7e63855cbacc8032 Mon Sep 17 00:00:00 2001 From: David Matlack Date: Wed, 22 Jun 2022 15:27:06 -0400 Subject: [PATCH] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels Currently KVM only zaps collapsible 4KiB SPTEs in the shadow MMU. This is fine for now since KVM never creates intermediate huge pages during dirty logging. In other words, KVM always replaces 1GiB pages directly with 4KiB pages, so there is no reason to look for collapsible 2MiB pages. However, this will stop being true once the shadow MMU participates in eager page splitting. During eager page splitting, each 1GiB is first split into 2MiB pages and then those are split into 4KiB pages. The intermediate 2MiB pages may be left behind if an error condition causes eager page splitting to bail early. No functional change intended. Reviewed-by: Peter Xu Signed-off-by: David Matlack Message-Id: <20220516232138.1783324-20-dmatlack@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 13a059a..7fdbb90 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6154,18 +6154,24 @@ restart: return need_tlb_flush; } +static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + /* + * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap + * pages that are already mapped at the maximum hugepage level. + */ + if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true)) + kvm_arch_flush_remote_tlbs_memslot(kvm, slot); +} + void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, const struct kvm_memory_slot *slot) { if (kvm_memslots_have_rmaps(kvm)) { write_lock(&kvm->mmu_lock); - /* - * Zap only 4k SPTEs since the legacy MMU only supports dirty - * logging at a 4k granularity and never creates collapsible - * 2m SPTEs during dirty logging. - */ - if (slot_handle_level_4k(kvm, slot, kvm_mmu_zap_collapsible_spte, true)) - kvm_arch_flush_remote_tlbs_memslot(kvm, slot); + kvm_rmap_zap_collapsible_sptes(kvm, slot); write_unlock(&kvm->mmu_lock); } -- 2.7.4