KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu

Allow adding new entries to the rmap and linking shadow pages without a
struct kvm_vcpu pointer by moving the implementation of rmap_add() and
link_shadow_page() into inner helper functions.

No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-16-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -673,11 +673,6 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
 	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
 }
 
-static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
-{
-	return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
-}
-
 static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
 {
 	kmem_cache_free(pte_list_desc_cache, pte_list_desc);
@@ -832,7 +827,7 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
 /*
  * Returns the number of pointers in the rmap chain, not counting the new one.
  */
-static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
+static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte,
 			struct kvm_rmap_head *rmap_head)
 {
 	struct pte_list_desc *desc;
@@ -843,7 +838,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 		rmap_head->val = (unsigned long)spte;
 	} else if (!(rmap_head->val & 1)) {
 		rmap_printk("%p %llx 1->many\n", spte, *spte);
-		desc = mmu_alloc_pte_list_desc(vcpu);
+		desc = kvm_mmu_memory_cache_alloc(cache);
 		desc->sptes[0] = (u64 *)rmap_head->val;
 		desc->sptes[1] = spte;
 		desc->spte_count = 2;
@@ -855,7 +850,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 		while (desc->spte_count == PTE_LIST_EXT) {
 			count += PTE_LIST_EXT;
 			if (!desc->more) {
-				desc->more = mmu_alloc_pte_list_desc(vcpu);
+				desc->more = kvm_mmu_memory_cache_alloc(cache);
 				desc = desc->more;
 				desc->spte_count = 0;
 				break;
@@ -1556,7 +1551,9 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 
 #define RMAP_RECYCLE_THRESHOLD 1000
 
-static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
+static void __rmap_add(struct kvm *kvm,
+		       struct kvm_mmu_memory_cache *cache,
+		       const struct kvm_memory_slot *slot,
 		       u64 *spte, gfn_t gfn)
 {
 	struct kvm_mmu_page *sp;
@@ -1566,15 +1563,23 @@ static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
 	sp = sptep_to_sp(spte);
 	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
 	rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
-	rmap_count = pte_list_add(vcpu, spte, rmap_head);
+	rmap_count = pte_list_add(cache, spte, rmap_head);
 
 	if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
-		kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
+		kvm_unmap_rmapp(kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
 		kvm_flush_remote_tlbs_with_address(
-				vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+				kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
 	}
 }
 
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
+		     u64 *spte, gfn_t gfn)
+{
+	struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache;
+
+	__rmap_add(vcpu->kvm, cache, slot, spte, gfn);
+}
+
 bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	bool young = false;
@@ -1645,13 +1650,13 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn)
 	return hash_64(gfn, KVM_MMU_HASH_SHIFT);
 }
 
-static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
+static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache,
 				    struct kvm_mmu_page *sp, u64 *parent_pte)
 {
 	if (!parent_pte)
 		return;
 
-	pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
+	pte_list_add(cache, parent_pte, &sp->parent_ptes);
 }
 
 static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
@@ -2247,7 +2252,7 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
 	__shadow_walk_next(iterator, *iterator->sptep);
 }
 
-static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+static void __link_shadow_page(struct kvm_mmu_memory_cache *cache, u64 *sptep,
 			       struct kvm_mmu_page *sp)
 {
 	u64 spte;
@@ -2258,12 +2263,18 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	mmu_spte_set(sptep, spte);
 
-	mmu_page_add_parent_pte(vcpu, sp, sptep);
+	mmu_page_add_parent_pte(cache, sp, sptep);
 
 	if (sp->unsync_children || sp->unsync)
 		mark_unsync(sptep);
 }
 
+static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+			     struct kvm_mmu_page *sp)
+{
+	__link_shadow_page(&vcpu->arch.mmu_pte_list_desc_cache, sptep, sp);
+}
+
 static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 				   unsigned direct_access)
 {