From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 20 May 2020 08:37:37 -0400
Subject: KVM: nVMX: always update CR3 in VMCS
Git-commit: df7e0681dd8acfa8d07816eaef232ded816d8a8c
Patch-mainline: 5.8-rc1
References: git-fixes

vmx_load_mmu_pgd is delaying the write of GUEST_CR3 to prepare_vmcs02 as
an optimization, but this is only correct before the nested vmentry.
If userspace is modifying CR3 with KVM_SET_SREGS after the VM has
already been put in guest mode, the value of CR3 will not be updated.
Remove the optimization, which almost never triggers anyway.

Fixes: 04f11ef45810 ("KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/x86/kvm/vmx/vmx.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2979,10 +2979,7 @@ void vmx_set_cr3(struct kvm_vcpu *vcpu,
 			spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
 		}
 
-		/* Loading vmcs02.GUEST_CR3 is handled by nested VM-Enter. */
-		if (is_guest_mode(vcpu))
-			update_guest_cr3 = false;
-		else if (enable_unrestricted_guest || is_paging(vcpu))
+		if (enable_unrestricted_guest || is_paging(vcpu))
 			guest_cr3 = kvm_read_cr3(vcpu);
 		else
 			guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;