KVM: PPC: Book3S HV: Migrate hot plugged memory

When a memory slot is hot plugged to a SVM, PFNs associated with the
GFNs in that slot must be migrated to the secure-PFNs, aka device-PFNs.

Call kvmppc_uv_migrate_mem_slot() to accomplish this.
Disable page-merge for all pages in the memory slot.
Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[rearranged the code, and modified the commit log]
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_book3s_uvmem.h

@@ -23,6 +23,10 @@ int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn);
 unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm);
 void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 			     struct kvm *kvm, bool skip_page_out);
+int kvmppc_uvmem_memslot_create(struct kvm *kvm,
+		const struct kvm_memory_slot *new);
+void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+		const struct kvm_memory_slot *old);
 #else
 static inline int kvmppc_uvmem_init(void)
 {
@@ -82,5 +86,15 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
 static inline void
 kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 			struct kvm *kvm, bool skip_page_out) { }
+
+static inline int  kvmppc_uvmem_memslot_create(struct kvm *kvm,
+		const struct kvm_memory_slot *new)
+{
+	return H_UNSUPPORTED;
+}
+
+static inline void  kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+		const struct kvm_memory_slot *old) { }
+
 #endif /* CONFIG_PPC_UV */
 #endif /* __ASM_KVM_BOOK3S_UVMEM_H__ */

arch/powerpc/kvm/book3s_hv.c

@@ -4523,16 +4523,14 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
 
 	switch (change) {
 	case KVM_MR_CREATE:
-		if (kvmppc_uvmem_slot_init(kvm, new))
-			return;
-		uv_register_mem_slot(kvm->arch.lpid,
-				     new->base_gfn << PAGE_SHIFT,
-				     new->npages * PAGE_SIZE,
-				     0, new->id);
+		/*
+		 * @TODO kvmppc_uvmem_memslot_create() can fail and
+		 * return error. Fix this.
+		 */
+		kvmppc_uvmem_memslot_create(kvm, new);
 		break;
 	case KVM_MR_DELETE:
-		uv_unregister_mem_slot(kvm->arch.lpid, old->id);
-		kvmppc_uvmem_slot_free(kvm, old);
+		kvmppc_uvmem_memslot_delete(kvm, old);
 		break;
 	default:
 		/* TODO: Handle KVM_MR_MOVE */

arch/powerpc/kvm/book3s_hv_uvmem.c

@@ -418,7 +418,7 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm,
 	return ret;
 }
 
-static void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+static void __kvmppc_uvmem_memslot_delete(struct kvm *kvm,
 		const struct kvm_memory_slot *memslot)
 {
 	uv_unregister_mem_slot(kvm->arch.lpid, memslot->id);
@@ -426,7 +426,7 @@ static void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
 	kvmppc_memslot_page_merge(kvm, memslot, true);
 }
 
-static int kvmppc_uvmem_memslot_create(struct kvm *kvm,
+static int __kvmppc_uvmem_memslot_create(struct kvm *kvm,
 		const struct kvm_memory_slot *memslot)
 {
 	int ret = H_PARAMETER;
@@ -478,7 +478,7 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 	/* register the memslot */
 	slots = kvm_memslots(kvm);
 	kvm_for_each_memslot(memslot, slots) {
-		ret = kvmppc_uvmem_memslot_create(kvm, memslot);
+		ret = __kvmppc_uvmem_memslot_create(kvm, memslot);
 		if (ret)
 			break;
 	}
@@ -488,7 +488,7 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 		kvm_for_each_memslot(m, slots) {
 			if (m == memslot)
 				break;
-			kvmppc_uvmem_memslot_delete(kvm, memslot);
+			__kvmppc_uvmem_memslot_delete(kvm, memslot);
 		}
 	}
 
@@ -1057,6 +1057,21 @@ int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
 	return (ret == U_SUCCESS) ? RESUME_GUEST : -EFAULT;
 }
 
+int kvmppc_uvmem_memslot_create(struct kvm *kvm, const struct kvm_memory_slot *new)
+{
+	int ret = __kvmppc_uvmem_memslot_create(kvm, new);
+
+	if (!ret)
+		ret = kvmppc_uv_migrate_mem_slot(kvm, new);
+
+	return ret;
+}
+
+void kvmppc_uvmem_memslot_delete(struct kvm *kvm, const struct kvm_memory_slot *old)
+{
+	__kvmppc_uvmem_memslot_delete(kvm, old);
+}
+
 static u64 kvmppc_get_secmem_size(void)
 {
 	struct device_node *np;