KVM: nVMX: Do not flush TLB on L1<->L2 transitions if L1 uses VPID and EPT (efebf0aa) · Commits · 戴 / test

arch/x86/kvm/vmx.c

+27 −10

Original line number	Diff line number	Diff line
		@@ -11964,6 +11964,25 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
		return 0;
		}

		/*
		* Returns if KVM is able to config CPU to tag TLB entries
		* populated by L2 differently than TLB entries populated
		* by L1.
		*
		* If L1 uses EPT, then TLB entries are tagged with different EPTP.
		*
		* If L1 uses VPID and we allocated a vpid02, TLB entries are tagged
		* with different VPID (L1 entries are tagged with vmx->vpid
		* while L2 entries are tagged with vmx->nested.vpid02).
		*/
		static bool nested_has_guest_tlb_tag(struct kvm_vcpu *vcpu)
		{
		struct vmcs12 *vmcs12 = get_vmcs12(vcpu);

		return nested_cpu_has_ept(vmcs12) \|\|
		(nested_cpu_has_vpid(vmcs12) && to_vmx(vcpu)->nested.vpid02);
		}

		static void prepare_vmcs02_full(struct kvm_vcpu vcpu, struct vmcs12 vmcs12)
		{
		struct vcpu_vmx *vmx = to_vmx(vcpu);
		@@ -12292,10 +12311,10 @@ static int prepare_vmcs02(struct kvm_vcpu vcpu, struct vmcs12 vmcs12,
		* influence global bitmap(for vpid01 and vpid02 allocation)
		* even if spawn a lot of nested vCPUs.
		*/
		if (nested_cpu_has_vpid(vmcs12) && vmx->nested.vpid02) {
		if (nested_cpu_has_vpid(vmcs12) && nested_has_guest_tlb_tag(vcpu)) {
		if (vmcs12->virtual_processor_id != vmx->nested.last_vpid) {
		vmx->nested.last_vpid = vmcs12->virtual_processor_id;
		__vmx_flush_tlb(vcpu, vmx->nested.vpid02, false);
		__vmx_flush_tlb(vcpu, nested_get_vpid02(vcpu), false);
		}
		} else {
		/*
		@@ -13194,23 +13213,21 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
		load_vmcs12_mmu_host_state(vcpu, vmcs12);

		/*
		* If vmcs01 don't use VPID, CPU flushes TLB on every
		* If vmcs01 doesn't use VPID, CPU flushes TLB on every
		* VMEntry/VMExit. Thus, no need to flush TLB.
		*
		* If vmcs12 uses VPID, TLB entries populated by L2 are
		* tagged with vmx->nested.vpid02 while L1 entries are tagged
		* with vmx->vpid. Thus, no need to flush TLB.
		* If vmcs12 doesn't use VPID, L1 expects TLB to be
		* flushed on every VMEntry/VMExit.
		*
		* Therefore, flush TLB only in case vmcs01 uses VPID and
		* vmcs12 don't use VPID as in this case L1 & L2 TLB entries
		* are both tagged with vmx->vpid.
		* Otherwise, we can preserve TLB entries as long as we are
		* able to tag L1 TLB entries differently than L2 TLB entries.
		*
		* If vmcs12 uses EPT, we need to execute this flush on EPTP01
		* and therefore we request the TLB flush to happen only after VMCS EPTP
		* has been set by KVM_REQ_LOAD_CR3.
		*/
		if (enable_vpid &&
		!(nested_cpu_has_vpid(vmcs12) && to_vmx(vcpu)->nested.vpid02)) {
		(!nested_cpu_has_vpid(vmcs12) \|\| !nested_has_guest_tlb_tag(vcpu))) {
		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
		}

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