KVM: x86/mmu: Add sptep_to_sp() helper to wrap shadow page lookup

Introduce sptep_to_sp() to reduce the boilerplate code needed to get the
shadow page associated with a spte pointer, and to improve readability
as it's not immediately obvious that "page_header" is a KVM-specific
accessor for retrieving a shadow page.

Signed-off-by: Sean Christopherson <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>

arch/x86/kvm/mmu/mmu.c

···
 
 static void count_spte_clear(u64 *sptep, u64 spte)
 {
-	struct kvm_mmu_page *sp =  page_header(__pa(sptep));
+	struct kvm_mmu_page *sp =  sptep_to_sp(sptep);
 
 	if (is_shadow_present_pte(spte))
 		return;
···
  */
 static u64 __get_spte_lockless(u64 *sptep)
 {
-	struct kvm_mmu_page *sp =  page_header(__pa(sptep));
+	struct kvm_mmu_page *sp =  sptep_to_sp(sptep);
 	union split_spte spte, *orig = (union split_spte *)sptep;
 	int count;
 
···
 	struct kvm_mmu_page *sp;
 	struct kvm_rmap_head *rmap_head;
 
-	sp = page_header(__pa(spte));
+	sp = sptep_to_sp(spte);
 	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
 	rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
 	return pte_list_add(vcpu, spte, rmap_head);
···
 	gfn_t gfn;
 	struct kvm_rmap_head *rmap_head;
 
-	sp = page_header(__pa(spte));
+	sp = sptep_to_sp(spte);
 	gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
 	rmap_head = gfn_to_rmap(kvm, gfn, sp);
 	__pte_list_remove(spte, rmap_head);
···
 static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
 {
 	if (is_large_pte(*sptep)) {
-		WARN_ON(page_header(__pa(sptep))->role.level == PG_LEVEL_4K);
+		WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
 		drop_spte(kvm, sptep);
 		--kvm->stat.lpages;
 		return true;
···
 static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
 {
 	if (__drop_large_spte(vcpu->kvm, sptep)) {
-		struct kvm_mmu_page *sp = page_header(__pa(sptep));
+		struct kvm_mmu_page *sp = sptep_to_sp(sptep);
 
 		kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
 			KVM_PAGES_PER_HPAGE(sp->role.level));
···
 	struct kvm_rmap_head *rmap_head;
 	struct kvm_mmu_page *sp;
 
-	sp = page_header(__pa(spte));
+	sp = sptep_to_sp(spte);
 
 	rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
 
···
 	struct kvm_mmu_page *sp;
 	unsigned int index;
 
-	sp = page_header(__pa(spte));
+	sp = sptep_to_sp(spte);
 	index = spte - sp->spt;
 	if (__test_and_set_bit(index, sp->unsync_child_bitmap))
 		return;
···
 
 static void clear_sp_write_flooding_count(u64 *spte)
 {
-	struct kvm_mmu_page *sp =  page_header(__pa(spte));
-
-	__clear_sp_write_flooding_count(sp);
+	__clear_sp_write_flooding_count(sptep_to_sp(spte));
 }
 
 static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
···
 	if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access))
 		return 0;
 
-	sp = page_header(__pa(sptep));
+	sp = sptep_to_sp(sptep);
 	if (sp_ad_disabled(sp))
 		spte |= SPTE_AD_DISABLED_MASK;
 	else if (kvm_vcpu_ad_need_write_protect(vcpu))
···
 {
 	struct kvm_mmu_page *sp;
 
-	sp = page_header(__pa(sptep));
+	sp = sptep_to_sp(sptep);
 
 	/*
 	 * Without accessed bits, there's no way to distinguish between
···
 			if (!is_shadow_present_pte(spte))
 				break;
 
-		sp = page_header(__pa(iterator.sptep));
+		sp = sptep_to_sp(iterator.sptep);
 		if (!is_last_spte(spte, sp->role.level))
 			break;
 
···
 
 restart:
 	for_each_rmap_spte(rmap_head, &iter, sptep) {
-		sp = page_header(__pa(sptep));
+		sp = sptep_to_sp(sptep);
 		pfn = spte_to_pfn(*sptep);
 
 		/*

arch/x86/kvm/mmu/mmu_audit.c

···
 	kvm_pfn_t pfn;
 	hpa_t hpa;
 
-	sp = page_header(__pa(sptep));
+	sp = sptep_to_sp(sptep);
 
 	if (sp->unsync) {
 		if (level != PG_LEVEL_4K) {
···
 	struct kvm_memory_slot *slot;
 	gfn_t gfn;
 
-	rev_sp = page_header(__pa(sptep));
+	rev_sp = sptep_to_sp(sptep);
 	gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt);
 
 	slots = kvm_memslots_for_spte_role(kvm, rev_sp->role);
···
 
 static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level)
 {
-	struct kvm_mmu_page *sp = page_header(__pa(sptep));
+	struct kvm_mmu_page *sp = sptep_to_sp(sptep);
 
 	if (vcpu->kvm->arch.audit_point == AUDIT_POST_SYNC && sp->unsync)
 		audit_printk(vcpu->kvm, "meet unsync sp(%p) after sync "

arch/x86/kvm/mmu/mmu_internal.h

···
 	return (struct kvm_mmu_page *)page_private(page);
 }
 
+static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
+{
+	return page_header(__pa(sptep));
+}
+
 void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,

arch/x86/kvm/mmu/paging_tmpl.h

···
 	u64 *spte;
 	int i;
 
-	sp = page_header(__pa(sptep));
+	sp = sptep_to_sp(sptep);
 
 	if (sp->role.level > PG_LEVEL_4K)
 		return;
···
 		level = iterator.level;
 		sptep = iterator.sptep;
 
-		sp = page_header(__pa(sptep));
+		sp = sptep_to_sp(sptep);
 		if (is_last_spte(*sptep, level)) {
 			pt_element_t gpte;
 			gpa_t pte_gpa;