KVM: x86: Add & use kvm_vcpu_is_legal_cr3() to check CR3's legality

Add and use kvm_vcpu_is_legal_cr3() to check CR3's legality to provide
a clear distinction between CR3 and GPA checks.  This will allow exempting
bits from kvm_vcpu_is_legal_cr3() without affecting general GPA checks,
e.g. for upcoming features that will use high bits in CR3 for feature
enabling.

No functional change intended.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-7-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: Binbin Wu

arch/x86/kvm/cpuid.h

@@ -279,4 +279,9 @@ static __always_inline bool guest_can_use(struct kvm_vcpu *vcpu,
 			vcpu->arch.governed_features.enabled);
 }
 
+static inline bool kvm_vcpu_is_legal_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
+{
+	return kvm_vcpu_is_legal_gpa(vcpu, cr3);
+}
+
 #endif

arch/x86/kvm/svm/nested.c

@@ -311,7 +311,7 @@ static bool __nested_vmcb_check_save(struct kvm_vcpu *vcpu,
 	if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) {
 		if (CC(!(save->cr4 & X86_CR4_PAE)) ||
 		    CC(!(save->cr0 & X86_CR0_PE)) ||
-		    CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3)))
+		    CC(!kvm_vcpu_is_legal_cr3(vcpu, save->cr3)))
 			return false;
 	}
 
@@ -520,7 +520,7 @@ static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
 static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 			       bool nested_npt, bool reload_pdptrs)
 {
-	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3)))
+	if (CC(!kvm_vcpu_is_legal_cr3(vcpu, cr3)))
 		return -EINVAL;
 
 	if (reload_pdptrs && !nested_npt && is_pae_paging(vcpu) &&

arch/x86/kvm/vmx/nested.c

@@ -1085,7 +1085,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 			       bool nested_ept, bool reload_pdptrs,
 			       enum vm_entry_failure_code *entry_failure_code)
 {
-	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3))) {
+	if (CC(!kvm_vcpu_is_legal_cr3(vcpu, cr3))) {
 		*entry_failure_code = ENTRY_FAIL_DEFAULT;
 		return -EINVAL;
 	}
@@ -2912,7 +2912,7 @@ static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu,
 
 	if (CC(!nested_host_cr0_valid(vcpu, vmcs12->host_cr0)) ||
 	    CC(!nested_host_cr4_valid(vcpu, vmcs12->host_cr4)) ||
-	    CC(kvm_vcpu_is_illegal_gpa(vcpu, vmcs12->host_cr3)))
+	    CC(!kvm_vcpu_is_legal_cr3(vcpu, vmcs12->host_cr3)))
 		return -EINVAL;
 
 	if (CC(is_noncanonical_address(vmcs12->host_ia32_sysenter_esp, vcpu)) ||

arch/x86/kvm/x86.c

@@ -1284,7 +1284,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 	 * stuff CR3, e.g. for RSM emulation, and there is no guarantee that
 	 * the current vCPU mode is accurate.
 	 */
-	if (kvm_vcpu_is_illegal_gpa(vcpu, cr3))
+	if (!kvm_vcpu_is_legal_cr3(vcpu, cr3))
 		return 1;
 
 	if (is_pae_paging(vcpu) && !load_pdptrs(vcpu, cr3))
@@ -11612,7 +11612,7 @@ static bool kvm_is_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
 		 */
 		if (!(sregs->cr4 & X86_CR4_PAE) || !(sregs->efer & EFER_LMA))
 			return false;
-		if (kvm_vcpu_is_illegal_gpa(vcpu, sregs->cr3))
+		if (!kvm_vcpu_is_legal_cr3(vcpu, sregs->cr3))
 			return false;
 	} else {
 		/*