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 <sheng@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 16 ++++++++++++++--
1 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 764f89b..f442da2 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;
}
@@ -692,6 +698,8 @@ 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;
@@ -723,6 +731,10 @@ 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;
}
--
1.7.0.1
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