KVM: split kvm_arch_set_memory_region into prepare and commit

Required for SRCU convertion later.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/ia64/kvm/kvm-ia64.c

@@ -1578,15 +1578,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	return r;
 }
 
-int kvm_arch_set_memory_region(struct kvm *kvm,
-		struct kvm_userspace_memory_region *mem,
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+		struct kvm_memory_slot *memslot,
 		struct kvm_memory_slot old,
+		struct kvm_userspace_memory_region *mem,
 		int user_alloc)
 {
 	unsigned long i;
 	unsigned long pfn;
-	int npages = mem->memory_size >> PAGE_SHIFT;
-	struct kvm_memory_slot *memslot = &kvm->memslots[mem->slot];
+	int npages = memslot->npages;
 	unsigned long base_gfn = memslot->base_gfn;
 
 	if (base_gfn + npages > (KVM_MAX_MEM_SIZE >> PAGE_SHIFT))
@@ -1610,6 +1610,14 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 	return 0;
 }
 
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+		struct kvm_userspace_memory_region *mem,
+		struct kvm_memory_slot old,
+		int user_alloc)
+{
+	return;
+}
+
 void kvm_arch_flush_shadow(struct kvm *kvm)
 {
 	kvm_flush_remote_tlbs(kvm);

arch/powerpc/kvm/powerpc.c

@@ -165,14 +165,24 @@ long kvm_arch_dev_ioctl(struct file *filp,
 	return -EINVAL;
 }
 
-int kvm_arch_set_memory_region(struct kvm *kvm,
-                               struct kvm_userspace_memory_region *mem,
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+                                   struct kvm_memory_slot *memslot,
                                    struct kvm_memory_slot old,
+                                   struct kvm_userspace_memory_region *mem,
                                    int user_alloc)
 {
 	return 0;
 }
 
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+               struct kvm_userspace_memory_region *mem,
+               struct kvm_memory_slot old,
+               int user_alloc)
+{
+       return;
+}
+
+
 void kvm_arch_flush_shadow(struct kvm *kvm)
 {
 }

arch/s390/kvm/kvm-s390.c

@@ -690,14 +690,12 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 }
 
 /* Section: memory related */
-int kvm_arch_set_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				   struct kvm_memory_slot *memslot,
 				   struct kvm_memory_slot old,
+				   struct kvm_userspace_memory_region *mem,
 				   int user_alloc)
 {
-	int i;
-	struct kvm_vcpu *vcpu;
-
 	/* A few sanity checks. We can have exactly one memory slot which has
 	   to start at guest virtual zero and which has to be located at a
 	   page boundary in userland and which has to end at a page boundary.
@@ -720,14 +718,23 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 	if (!user_alloc)
 		return -EINVAL;
 
+	return 0;
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+				struct kvm_userspace_memory_region *mem,
+				struct kvm_memory_slot old,
+				int user_alloc)
+{
+	int i;
+	struct kvm_vcpu *vcpu;
+
 	/* request update of sie control block for all available vcpus */
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (test_and_set_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
 			continue;
 		kvm_s390_inject_sigp_stop(vcpu, ACTION_RELOADVCPU_ON_STOP);
 	}
-
-	return 0;
 }
 
 void kvm_arch_flush_shadow(struct kvm *kvm)

arch/x86/kvm/x86.c

@@ -5228,13 +5228,13 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kfree(kvm);
 }
 
-int kvm_arch_set_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				struct kvm_memory_slot *memslot,
 				struct kvm_memory_slot old,
+				struct kvm_userspace_memory_region *mem,
 				int user_alloc)
 {
-	int npages = mem->memory_size >> PAGE_SHIFT;
-	struct kvm_memory_slot *memslot = &kvm->memslots->memslots[mem->slot];
+	int npages = memslot->npages;
 
 	/*To keep backward compatibility with older userspace,
 	 *x86 needs to hanlde !user_alloc case.
@@ -5254,12 +5254,23 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 			if (IS_ERR((void *)userspace_addr))
 				return PTR_ERR((void *)userspace_addr);
 
-			/* set userspace_addr atomically for kvm_hva_to_rmapp */
-			spin_lock(&kvm->mmu_lock);
 			memslot->userspace_addr = userspace_addr;
-			spin_unlock(&kvm->mmu_lock);
-		} else {
-			if (!old.user_alloc && old.rmap) {
+		}
+	}
+
+
+	return 0;
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+				struct kvm_userspace_memory_region *mem,
+				struct kvm_memory_slot old,
+				int user_alloc)
+{
+
+	int npages = mem->memory_size >> PAGE_SHIFT;
+
+	if (!user_alloc && !old.user_alloc && old.rmap && !npages) {
 		int ret;
 
 		down_write(&current->mm->mmap_sem);
@@ -5271,8 +5282,6 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 			       "kvm_vm_ioctl_set_memory_region: "
 			       "failed to munmap memory\n");
 	}
-		}
-	}
 
 	spin_lock(&kvm->mmu_lock);
 	if (!kvm->arch.n_requested_mmu_pages) {
@@ -5282,8 +5291,6 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 
 	kvm_mmu_slot_remove_write_access(kvm, mem->slot);
 	spin_unlock(&kvm->mmu_lock);
-
-	return 0;
 }
 
 void kvm_arch_flush_shadow(struct kvm *kvm)

include/linux/kvm_host.h

@@ -253,7 +253,12 @@ int kvm_set_memory_region(struct kvm *kvm,
 int __kvm_set_memory_region(struct kvm *kvm,
 			    struct kvm_userspace_memory_region *mem,
 			    int user_alloc);
-int kvm_arch_set_memory_region(struct kvm *kvm,
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				struct kvm_memory_slot *memslot,
+				struct kvm_memory_slot old,
+				struct kvm_userspace_memory_region *mem,
+				int user_alloc);
+void kvm_arch_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
 				struct kvm_memory_slot old,
 				int user_alloc);

virt/kvm/kvm_main.c

@@ -663,6 +663,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (!npages)
 		kvm_arch_flush_shadow(kvm);
 
+	r = kvm_arch_prepare_memory_region(kvm, &new, old, mem, user_alloc);
+	if (r)
+		goto out_free;
+
 	spin_lock(&kvm->mmu_lock);
 	if (mem->slot >= kvm->memslots->nmemslots)
 		kvm->memslots->nmemslots = mem->slot + 1;
@@ -670,13 +674,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	*memslot = new;
 	spin_unlock(&kvm->mmu_lock);
 
-	r = kvm_arch_set_memory_region(kvm, mem, old, user_alloc);
-	if (r) {
-		spin_lock(&kvm->mmu_lock);
-		*memslot = old;
-		spin_unlock(&kvm->mmu_lock);
-		goto out_free;
-	}
+	kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);
 
 	kvm_free_physmem_slot(&old, npages ? &new : NULL);
 	/* Slot deletion case: we have to update the current slot */