KVM: x86/mmu: Merge TDP MMU put and free root

kvm_tdp_mmu_put_root and kvm_tdp_mmu_free_root are always called
together, so merge the functions to simplify TDP MMU root refcounting /
freeing.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210401233736.638171-5-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -3120,8 +3120,8 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
 
 	sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK);
 
-	if (is_tdp_mmu_page(sp) && kvm_tdp_mmu_put_root(kvm, sp))
-		kvm_tdp_mmu_free_root(kvm, sp);
+	if (is_tdp_mmu_page(sp))
+		kvm_tdp_mmu_put_root(kvm, sp);
 	else if (!--sp->root_count && sp->role.invalid)
 		kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);
 

arch/x86/kvm/mmu/tdp_mmu.c

@@ -41,10 +41,31 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm)
 	rcu_barrier();
 }
 
-static void tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root)
+static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
+			  gfn_t start, gfn_t end, bool can_yield, bool flush);
+
+static void tdp_mmu_free_sp(struct kvm_mmu_page *sp)
 {
-	if (kvm_tdp_mmu_put_root(kvm, root))
-		kvm_tdp_mmu_free_root(kvm, root);
+	free_page((unsigned long)sp->spt);
+	kmem_cache_free(mmu_page_header_cache, sp);
+}
+
+void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root)
+{
+	gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT);
+
+	lockdep_assert_held_write(&kvm->mmu_lock);
+
+	if (--root->root_count)
+		return;
+
+	WARN_ON(!root->tdp_mmu_page);
+
+	list_del(&root->link);
+
+	zap_gfn_range(kvm, root, 0, max_gfn, false, false);
+
+	tdp_mmu_free_sp(root);
 }
 
 static inline bool tdp_mmu_next_root_valid(struct kvm *kvm,
@@ -66,7 +87,7 @@ static inline struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
 	struct kvm_mmu_page *next_root;
 
 	next_root = list_next_entry(root, link);
-	tdp_mmu_put_root(kvm, root);
+	kvm_tdp_mmu_put_root(kvm, root);
 	return next_root;
 }
 
@@ -89,31 +110,6 @@ static inline struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
 		if (kvm_mmu_page_as_id(_root) != _as_id) {		\
 		} else
 
-static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
-			  gfn_t start, gfn_t end, bool can_yield, bool flush);
-
-static void tdp_mmu_free_sp(struct kvm_mmu_page *sp)
-{
-	free_page((unsigned long)sp->spt);
-	kmem_cache_free(mmu_page_header_cache, sp);
-}
-
-void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root)
-{
-	gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT);
-
-	lockdep_assert_held_write(&kvm->mmu_lock);
-
-	WARN_ON(root->root_count);
-	WARN_ON(!root->tdp_mmu_page);
-
-	list_del(&root->link);
-
-	zap_gfn_range(kvm, root, 0, max_gfn, false, false);
-
-	tdp_mmu_free_sp(root);
-}
-
 static union kvm_mmu_page_role page_role_for_level(struct kvm_vcpu *vcpu,
 						   int level)
 {

arch/x86/kvm/mmu/tdp_mmu.h

@@ -6,7 +6,6 @@
 #include <linux/kvm_host.h>
 
 hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu);
-void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root);
 
 static inline void kvm_tdp_mmu_get_root(struct kvm *kvm,
 					struct kvm_mmu_page *root)
@@ -17,14 +16,7 @@ static inline void kvm_tdp_mmu_get_root(struct kvm *kvm,
 	++root->root_count;
 }
 
-static inline bool kvm_tdp_mmu_put_root(struct kvm *kvm,
-					struct kvm_mmu_page *root)
-{
-	lockdep_assert_held(&kvm->mmu_lock);
-	--root->root_count;
-
-	return !root->root_count;
-}
+void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root);
 
 bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start,
 				 gfn_t end, bool can_yield, bool flush);