[PATCH v12 47/84] KVM: x86/mmu: Don't mark unused faultin pages as accessed
From: Sean Christopherson <seanjc@google.com>
Date: 2024-07-26 23:54:15
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
When finishing guest page faults, don't mark pages as accessed if KVM is resuming the guest _without_ installing a mapping, i.e. if the page isn't being used. While it's possible that marking the page accessed could avoid minor thrashing due to reclaiming a page that the guest is about to access, it's far more likely that the gfn=>pfn mapping was was invalidated, e.g. due a memslot change, or because the corresponding VMA is being modified. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/mmu/mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3cdb1bd80823..95beb50748fc 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c@@ -4339,7 +4339,9 @@ static void kvm_mmu_finish_page_fault(struct kvm_vcpu *vcpu, * fault handler, and so KVM must (somewhat) speculatively mark the * folio dirty if KVM could locklessly make the SPTE writable. */ - if (!fault->map_writable || r == RET_PF_RETRY) + if (r == RET_PF_RETRY) + kvm_release_page_unused(fault->refcounted_page); + else if (!fault->map_writable) kvm_release_page_clean(fault->refcounted_page); else kvm_release_page_dirty(fault->refcounted_page);
--
2.46.0.rc1.232.g9752f9e123-goog