KVM: nSVM: CR3 MBZ bits are only 63:52

Commit 761e4169 created a wrong mask for the
CR3 MBZ bits. According to APM vol 2, only the upper 12 bits are MBZ.

Fixes: 761e4169 ("KVM: nSVM: Check that MBZ bits in CR3 and CR4 are not set on vmrun of nested guests", 2020-07-08)
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Message-Id: <20200829004824.4577-2-krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -237,7 +237,7 @@ static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb12)
 	} else {
 		if (!(vmcb12->save.cr4 & X86_CR4_PAE) ||
 		    !(vmcb12->save.cr0 & X86_CR0_PE) ||
-		    (vmcb12->save.cr3 & MSR_CR3_LONG_RESERVED_MASK))
+		    (vmcb12->save.cr3 & MSR_CR3_LONG_MBZ_MASK))
 			return false;
 	}
 	if (kvm_valid_cr4(&svm->vcpu, vmcb12->save.cr4))

arch/x86/kvm/svm/svm.h

@@ -339,7 +339,7 @@ static inline bool gif_set(struct vcpu_svm *svm)
 /* svm.c */
 #define MSR_CR3_LEGACY_RESERVED_MASK		0xfe7U
 #define MSR_CR3_LEGACY_PAE_RESERVED_MASK	0x7U
-#define MSR_CR3_LONG_RESERVED_MASK		0xfff0000000000fe7U
+#define MSR_CR3_LONG_MBZ_MASK			0xfff0000000000000U
 #define MSR_INVALID				0xffffffffU
 
 u32 svm_msrpm_offset(u32 msr);