[PATCH v2] KVM: VMX: Fix 32bit Windows blue screen with EPT

[Sheng Yang <sheng@linux.intel.com>]

After CR0 is changed during VMExit, the result of kvm_read_cr3() may be
different. Commit d95bfcdd7cda4dfdac9588e684bc7c75794a075e "KVM: Fetch guest
cr3 from hardware on demand" caused 32bit Windows guest blue screen when using
with EPT. This patch fixes it by decache CR3 before CR0 change, for both
paging to nonpaging, and nonpaging to paging switch.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
 arch/x86/kvm/vmx.c |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f107315..bf89ec2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1921,8 +1921,7 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
 					unsigned long cr0,
 					struct kvm_vcpu *vcpu)
 {
-	ulong cr3;
-
+	vmx_decache_cr3(vcpu);
 	if (!(cr0 & X86_CR0_PG)) {
 		/* From paging/starting to nonpaging */
 		vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
@@ -1937,11 +1936,8 @@ static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
 			     vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
 			     ~(CPU_BASED_CR3_LOAD_EXITING |
 			       CPU_BASED_CR3_STORE_EXITING));
-		/* Must fetch cr3 before updating cr0 */
-		cr3 = kvm_read_cr3(vcpu);
 		vcpu->arch.cr0 = cr0;
 		vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
-		vmx_set_cr3(vcpu, cr3);
 	}
 
 	if (!(cr0 & X86_CR0_WP))
-- 
1.7.0.1