From fca91f6d60b6ee53b8d43c8ad5bad153a758961c Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@google.com>
Date: Wed, 15 Mar 2017 07:40:55 -0700
Subject: [PATCH] kvm: nVMX: Set VM instruction error for VMPTRLD of unbacked
page
It is never correct for a VMX instruction to fail with "invalid VMCS"
if there is, in fact, a current VMCS. Reads from unbacked addresses
return all 1's, which means that an unbacked VMCS will not have the
correct VMCS revision ID (i.e. VMCS12_REVISION).
Fixes: 63846663eac78 ("KVM: nVMX: Implement VMPTRLD")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d78fe0abf9ac1..c379d0bfdcba9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9318,9 +9318,17 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
struct vmcs12 *new_vmcs12;
struct page *page;
page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
- if (is_error_page(page))
- return nested_vmx_failInvalid(vcpu);
-
+ if (is_error_page(page)) {
+ /*
+ * Reads from an unbacked page return all 1s,
+ * which means that the 32 bits located at the
+ * given physical address won't match the required
+ * VMCS12_REVISION identifier.
+ */
+ nested_vmx_failValid(vcpu,
+ VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
+ return kvm_skip_emulated_instruction(vcpu);
+ }
new_vmcs12 = kmap(page);
if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
(new_vmcs12->hdr.shadow_vmcs &&
--
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