kvm: nVMX: Fix nested_vmx_check_msr_bitmap_controls

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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 22034ac4b5f2..e02c7004b64b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4634,6 +4634,11 @@ 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;
@@ -9611,20 +9616,10 @@ static int nested_vmx_check_io_bitmap_controls(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;