[PATCH v2] KVM: nVMX: Fix nested_vmx_check_msr_bitmap_controls

[Jim Mattson <jmattson@google.com>]

Allow the L1 guest to specify the last page of addressable guest
physical memory for an L2 MSR permission bitmap. Also remove the
vmcs12_read_any() check that should never fail.

Fixes: 3af18d9c5fe95 ("KVM: nVMX: Prepare for using hardware MSR bitmap")
Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 60fa010d3fa1..8b403682dcdf 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4624,6 +4624,11 @@ static bool guest_state_valid(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static bool page_address_valid(struct kvm_vcpu *vcpu, gpa_t gpa)
+{
+	return PAGE_ALIGNED(gpa) && !(gpa >> cpuid_maxphyaddr(vcpu));
+}
+
 static int init_rmode_tss(struct kvm *kvm)
 {
 	gfn_t fn;
@@ -9559,20 +9564,10 @@ static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu)
 static int nested_vmx_check_msr_bitmap_controls(struct kvm_vcpu *vcpu,
 						struct vmcs12 *vmcs12)
 {
-	int maxphyaddr;
-	u64 addr;
-
 	if (!nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS))
 		return 0;
 
-	if (vmcs12_read_any(vcpu, MSR_BITMAP, &addr)) {
-		WARN_ON(1);
-		return -EINVAL;
-	}
-	maxphyaddr = cpuid_maxphyaddr(vcpu);
-
-	if (!PAGE_ALIGNED(vmcs12->msr_bitmap) ||
-	   ((addr + PAGE_SIZE) >> maxphyaddr))
+	if (!page_address_valid(vcpu, vmcs12->msr_bitmap))
 		return -EINVAL;
 
 	return 0;
-- 
2.13.1.518.g3df882009-goog