KVM: nVMX: Selectively use TLB_FLUSH_CURRENT for nested VM-Enter/VM-Exit (c51e1ffe) · Commits · 戴 / test

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 <sean.j.christopherson@intel.com> Message-Id: <20200320212833.3507-27-sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/nested.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -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;

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