From c51e1ffee50121a2b2e00208f517a695493ee85d Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 20 Mar 2020 14:28:22 -0700 Subject: [PATCH] KVM: nVMX: Selectively use TLB_FLUSH_CURRENT for nested VM-Enter/VM-Exit Flush only the current context, as opposed to all contexts, when requesting a TLB flush to handle the scenario where a L1 does not expect a TLB flush, but one is required because L1 and L2 shared an ASID. This occurs if EPT is disabled (no per-EPTP tag), VPID is enabled (hardware doesn't flush unconditionally) and vmcs02 does not have its own VPID due to exhaustion of available VPIDs. Signed-off-by: Sean Christopherson Message-Id: <20200320212833.3507-27-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 567a7a0..deddf0f 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -1152,8 +1152,8 @@ static void nested_vmx_transition_tlb_flush(struct kvm_vcpu *vcpu, * * If VPID is enabled and used by vmc12, but L2 does not have a unique * TLB tag (ASID), i.e. EPT is disabled and KVM was unable to allocate - * a VPID for L2, flush the TLB as the effective ASID is common to both - * L1 and L2. + * a VPID for L2, flush the current context as the effective ASID is + * common to both L1 and L2. * * Defer the flush so that it runs after vmcs02.EPTP has been set by * KVM_REQ_LOAD_MMU_PGD (if nested EPT is enabled) and to avoid @@ -1165,8 +1165,10 @@ static void nested_vmx_transition_tlb_flush(struct kvm_vcpu *vcpu, * mapping between vpid02 and vpid12, vpid02 is per-vCPU and reused for * all nested vCPUs. */ - if (!nested_cpu_has_vpid(vmcs12) || !nested_has_guest_tlb_tag(vcpu)) { + if (!nested_cpu_has_vpid(vmcs12)) { kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); + } else if (!nested_has_guest_tlb_tag(vcpu)) { + kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } else if (is_vmenter && vmcs12->virtual_processor_id != vmx->nested.last_vpid) { vmx->nested.last_vpid = vmcs12->virtual_processor_id; -- 2.7.4