KVM: Fetch guest cr3 from hardware on demand

Instead of syncing the guest cr3 every exit, which is expensince on vmx
with ept enabled, sync it only on demand.

[sheng: fix incorrect cr3 seen by Windows XP]

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6e50314d64fb..fa708c9a7437 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -667,6 +667,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
         if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT)))
                 return 1;
         vcpu->arch.cr3 = cr3;
+        __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
         vcpu->arch.mmu.new_cr3(vcpu);
         return 0;
 }
@@ -5583,6 +5584,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
         vcpu->arch.cr2 = sregs->cr2;
         mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3;
         vcpu->arch.cr3 = sregs->cr3;
+        __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
 
         kvm_set_cr8(vcpu, sregs->cr8);