From 8c4182bd27cafc2b0f94564485c89ed366c1572c Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 10 Jul 2020 17:48:10 +0200 Subject: [PATCH] KVM: VMX: optimize #PF injection when MAXPHYADDR does not match Ignore non-present page faults, since those cannot have reserved bits set. When running access.flat with "-cpu Haswell,phys-bits=36", the number of trapped page faults goes down from 8872644 to 3978948. Signed-off-by: Paolo Bonzini Message-Id: <20200710154811.418214-9-mgamal@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 5518f75c9b19..962a78c7dde5 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4355,6 +4355,16 @@ static void init_vmcs(struct vcpu_vmx *vmx) vmx->pt_desc.guest.output_mask = 0x7F; vmcs_write64(GUEST_IA32_RTIT_CTL, 0); } + + /* + * If EPT is enabled, #PF is only trapped if MAXPHYADDR is mismatched + * between guest and host. In that case we only care about present + * faults. + */ + if (enable_ept) { + vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, PFERR_PRESENT_MASK); + vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, PFERR_PRESENT_MASK); + } } static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) -- 2.11.0