Commit aad82703 authored by Sheng Yang's avatar Sheng Yang Committed by Avi Kivity
Browse files

KVM: VMX: Only reset MMU when necessary 



Only modifying some bits of CR0/CR4 needs paging mode switch.

Modify EFER.NXE bit would result in reserved bit updates.

Signed-off-by: default avatarSheng Yang <sheng@linux.intel.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 62ad0755

arch/x86/kvm/x86.c

+14 −2
Original line number Diff line number Diff line
@@ -416,6 +416,10 @@ static bool pdptrs_changed(struct kvm_vcpu *vcpu) 


static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)

{

	unsigned long old_cr0 = kvm_read_cr0(vcpu);

	unsigned long update_bits = X86_CR0_PG | X86_CR0_WP |

				    X86_CR0_CD | X86_CR0_NW;



	cr0 |= X86_CR0_ET;



#ifdef CONFIG_X86_64
@@ -449,6 +453,7 @@ static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) 


	kvm_x86_ops->set_cr0(vcpu, cr0);



	if ((cr0 ^ old_cr0) & update_bits)

		kvm_mmu_reset_context(vcpu);

	return 0;

}
@@ -487,6 +492,7 @@ int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) 


	kvm_x86_ops->set_cr4(vcpu, cr4);



	if ((cr4 ^ old_cr4) & pdptr_bits)

		kvm_mmu_reset_context(vcpu);



	return 0;
@@ -693,6 +699,8 @@ static u32 emulated_msrs[] = { 


static int set_efer(struct kvm_vcpu *vcpu, u64 efer)

{

	u64 old_efer = vcpu->arch.efer;



	if (efer & efer_reserved_bits)

		return 1;
@@ -724,6 +732,10 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer) 
	vcpu->arch.mmu.base_role.nxe = (efer & EFER_NX) && !tdp_enabled;

	kvm_mmu_reset_context(vcpu);



	/* Update reserved bits */

	if ((efer ^ old_efer) & EFER_NX)

		kvm_mmu_reset_context(vcpu);



	return 0;

}