KVM: MMU: Introduce struct kvm_page_fault

Create a single structure for arguments that are passed from
kvm_mmu_do_page_fault to the page fault handlers.  Later
the structure will grow to include various output parameters
that are passed back to the next steps in the page fault
handling.
Suggested-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.h

@@ -114,17 +114,45 @@ static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu)
 					  vcpu->arch.mmu->shadow_root_level);
 }
 
+struct kvm_page_fault {
+	/* arguments to kvm_mmu_do_page_fault.  */
+	const gpa_t addr;
+	const u32 error_code;
+	const bool prefault;
+
+	/* Derived from error_code.  */
+	const bool exec;
+	const bool write;
+	const bool present;
+	const bool rsvd;
+	const bool user;
+
+	/* Derived from mmu.  */
+	const bool is_tdp;
+};
+
 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		       bool prefault);
 
 static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 					u32 err, bool prefault)
 {
+	struct kvm_page_fault fault = {
+		.addr = cr2_or_gpa,
+		.error_code = err,
+		.exec = err & PFERR_FETCH_MASK,
+		.write = err & PFERR_WRITE_MASK,
+		.present = err & PFERR_PRESENT_MASK,
+		.rsvd = err & PFERR_RSVD_MASK,
+		.user = err & PFERR_USER_MASK,
+		.prefault = prefault,
+		.is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
+	};
 #ifdef CONFIG_RETPOLINE
-	if (likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault))
-		return kvm_tdp_page_fault(vcpu, cr2_or_gpa, err, prefault);
+	if (fault.is_tdp)
+		return kvm_tdp_page_fault(vcpu, fault.addr, fault.error_code, fault.prefault);
 #endif
-	return vcpu->arch.mmu->page_fault(vcpu, cr2_or_gpa, err, prefault);
+	return vcpu->arch.mmu->page_fault(vcpu, fault.addr, fault.error_code, fault.prefault);
 }
 
 /*