From aad827034e419fa8c5ec39e6455266f0b942d856 Mon Sep 17 00:00:00 2001 From: Sheng Yang Date: Wed, 12 May 2010 16:40:42 +0800 Subject: [PATCH] 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: Sheng Yang Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 03039fd8698..78147f0421a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -416,6 +416,10 @@ out: 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 @@ -449,7 +453,8 @@ static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) kvm_x86_ops->set_cr0(vcpu, cr0); - kvm_mmu_reset_context(vcpu); + if ((cr0 ^ old_cr0) & update_bits) + kvm_mmu_reset_context(vcpu); return 0; } @@ -487,7 +492,8 @@ int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) kvm_x86_ops->set_cr4(vcpu, cr4); - kvm_mmu_reset_context(vcpu); + 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; } -- 2.39.5