Commit 1196cb97 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: nVMX: Reload APIC access page on nested VM-Exit only if necessary 



Defer reloading L1's APIC page by logging the need for a reload and
processing it during nested VM-Exit instead of unconditionally reloading
the APIC page on nested VM-Exit.  This eliminates a TLB flush on the
majority of VM-Exits as the APIC page rarely needs to be reloaded.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200320212833.3507-28-sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c51e1ffe

arch/x86/kvm/vmx/nested.c

+4 −5
Original line number Diff line number Diff line
@@ -4346,11 +4346,10 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, 
	kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);

	vmx->nested.pi_desc = NULL;



	/*

	 * We are now running in L2, mmu_notifier will force to reload the

	 * page's hpa for L2 vmcs. Need to reload it for L1 before entering L1.

	 */

	if (vmx->nested.reload_vmcs01_apic_access_page) {

		vmx->nested.reload_vmcs01_apic_access_page = false;

		kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu);

	}



	if ((exit_reason != -1) && (enable_shadow_vmcs || vmx->nested.hv_evmcs))

		vmx->nested.need_vmcs12_to_shadow_sync = true;

arch/x86/kvm/vmx/vmx.c

+7 −3
Original line number Diff line number Diff line
@@ -6142,11 +6142,15 @@ void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu) 


static void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu, hpa_t hpa)

{

	if (!is_guest_mode(vcpu)) {

	/* Defer reload until vmcs01 is the current VMCS. */

	if (is_guest_mode(vcpu)) {

		to_vmx(vcpu)->nested.reload_vmcs01_apic_access_page = true;

		return;

	}



	vmcs_write64(APIC_ACCESS_ADDR, hpa);

	vmx_flush_tlb_current(vcpu);

}

}



static void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)

{

arch/x86/kvm/vmx/vmx.h

+1 −0
Original line number Diff line number Diff line
@@ -136,6 +136,7 @@ struct nested_vmx { 
	bool vmcs02_initialized;



	bool change_vmcs01_virtual_apic_mode;

	bool reload_vmcs01_apic_access_page;



	/*

	 * Enlightened VMCS has been enabled. It does not mean that L1 has to

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