KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page()

Get the kvm pointer from the caller, rather than deriving it from
vcpu->kvm, and plumb the kvm pointer all the way from
kvm_mmu_get_shadow_page(). With this change in place, the vcpu pointer
is only needed to sync indirect shadow pages. In other words,
__kvm_mmu_get_shadow_page() can now be used to get *direct* shadow pages
without a vcpu pointer. This enables eager page splitting, which needs
to allocate direct shadow pages during VM ioctls.

No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-13-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -1975,7 +1975,8 @@ static void clear_sp_write_flooding_count(u64 *spte)
 	__clear_sp_write_flooding_count(sptep_to_sp(spte));
 }
 
-static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
+						     struct kvm_vcpu *vcpu,
 						     gfn_t gfn,
 						     struct hlist_head *sp_list,
 						     union kvm_mmu_page_role role)
@@ -1985,7 +1986,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
 	int collisions = 0;
 	LIST_HEAD(invalid_list);
 
-	for_each_valid_sp(vcpu->kvm, sp, sp_list) {
+	for_each_valid_sp(kvm, sp, sp_list) {
 		if (sp->gfn != gfn) {
 			collisions++;
 			continue;
@@ -2002,7 +2003,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
 			 * upper-level page will be write-protected.
 			 */
 			if (role.level > PG_LEVEL_4K && sp->unsync)
-				kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
+				kvm_mmu_prepare_zap_page(kvm, sp,
 							 &invalid_list);
 			continue;
 		}
@@ -2030,7 +2031,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
 
 			WARN_ON(!list_empty(&invalid_list));
 			if (ret > 0)
-				kvm_flush_remote_tlbs(vcpu->kvm);
+				kvm_flush_remote_tlbs(kvm);
 		}
 
 		__clear_sp_write_flooding_count(sp);
@@ -2039,13 +2040,13 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
 	}
 
 	sp = NULL;
-	++vcpu->kvm->stat.mmu_cache_miss;
+	++kvm->stat.mmu_cache_miss;
 
 out:
-	kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+	kvm_mmu_commit_zap_page(kvm, &invalid_list);
 
-	if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
-		vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+	if (collisions > kvm->stat.max_mmu_page_hash_collisions)
+		kvm->stat.max_mmu_page_hash_collisions = collisions;
 	return sp;
 }
 
@@ -2089,7 +2090,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
 	return sp;
 }
 
-static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,
+						      struct kvm_vcpu *vcpu,
 						      struct shadow_page_caches *caches,
 						      gfn_t gfn,
 						      union kvm_mmu_page_role role)
@@ -2098,12 +2100,12 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
 	struct kvm_mmu_page *sp;
 	bool created = false;
 
-	sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+	sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
 
-	sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
+	sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role);
 	if (!sp) {
 		created = true;
-		sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
+		sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role);
 	}
 
 	trace_kvm_mmu_get_page(sp, created);
@@ -2120,7 +2122,7 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
 		.gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
 	};
 
-	return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+	return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
 }
 
 static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, unsigned int access)