KVM: MMU: introduce is_shadow_zero_bits_set()

We have the same data struct to check reserved bits on guest page tables
and shadow page tables, split is_rsvd_bits_set() so that the logic can be
shared between these two paths
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -3268,6 +3268,25 @@ static gpa_t nonpaging_gva_to_gpa_nested(struct kvm_vcpu *vcpu, gva_t vaddr,
 	return vcpu->arch.nested_mmu.translate_gpa(vcpu, vaddr, access, exception);
 }
 
+static bool
+__is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check, u64 pte, int level)
+{
+	int bit7 = (pte >> 7) & 1, low6 = pte & 0x3f;
+
+	return (pte & rsvd_check->rsvd_bits_mask[bit7][level-1]) |
+		((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0);
+}
+
+static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
+{
+	return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level);
+}
+
+static bool is_shadow_zero_bits_set(struct kvm_mmu *mmu, u64 spte, int level)
+{
+	return __is_rsvd_bits_set(&mmu->shadow_zero_check, spte, level);
+}
+
 static bool quickly_check_mmio_pf(struct kvm_vcpu *vcpu, u64 addr, bool direct)
 {
 	if (direct)
@@ -3546,15 +3565,6 @@ static inline bool is_last_gpte(struct kvm_mmu *mmu, unsigned level, unsigned gp
 	return mmu->last_pte_bitmap & (1 << index);
 }
 
-static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
-{
-	struct rsvd_bits_validate *rsvd_check = &mmu->guest_rsvd_check;
-	int bit7 = (gpte >> 7) & 1, low6 = gpte & 0x3f;
-
-	return (gpte & rsvd_check->rsvd_bits_mask[bit7][level-1]) |
-		((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0);
-}
-
 #define PTTYPE_EPT 18 /* arbitrary */
 #define PTTYPE PTTYPE_EPT
 #include "paging_tmpl.h"