Commit 284036c6 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: nVMX: Remove obsolete MSR bitmap refresh at nested transitions 



Drop unnecessary MSR bitmap updates during nested transitions, as L1's
APIC_BASE MSR is not modified by the standard VM-Enter/VM-Exit flows,
and L2's MSR bitmap is managed separately.  In the unlikely event that L1
is pathological and loads APIC_BASE via the VM-Exit load list, KVM will
handle updating the bitmap in its normal WRMSR flows.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-39-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9e4784e1

arch/x86/kvm/vmx/nested.c

+0 −6
Original line number Diff line number Diff line
@@ -4305,9 +4305,6 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, 
	kvm_set_dr(vcpu, 7, 0x400);

	vmcs_write64(GUEST_IA32_DEBUGCTL, 0);



	if (cpu_has_vmx_msr_bitmap())

		vmx_update_msr_bitmap(vcpu);



	if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr,

				vmcs12->vm_exit_msr_load_count))

		nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_MSR_FAIL);
@@ -4386,9 +4383,6 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu) 


	kvm_mmu_reset_context(vcpu);



	if (cpu_has_vmx_msr_bitmap())

		vmx_update_msr_bitmap(vcpu);



	/*

	 * This nasty bit of open coding is a compromise between blindly

	 * loading L1's MSRs using the exit load lists (incorrect emulation

arch/x86/kvm/vmx/vmx.c

+1 −1
Original line number Diff line number Diff line
@@ -3865,7 +3865,7 @@ static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu, u8 mode) 
	}

}



void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu)

static void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	u8 mode = vmx_msr_bitmap_mode(vcpu);

arch/x86/kvm/vmx/vmx.h

+0 −1
Original line number Diff line number Diff line
@@ -376,7 +376,6 @@ u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level); 


bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu);

void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu);

void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu);

bool vmx_nmi_blocked(struct kvm_vcpu *vcpu);

bool vmx_interrupt_blocked(struct kvm_vcpu *vcpu);

bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu);