KVM: set_memory_region: Refactor commit_memory_region()

This patch makes the parameter old a const pointer to the old memory
slot and adds a new parameter named change to know the change being
requested: the former is for removing extra copying and the latter is
for cleaning up the code.
Signed-off-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/arm/kvm/arm.c

@@ -238,7 +238,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   struct kvm_userspace_memory_region *mem,
-				   struct kvm_memory_slot old)
+				   const struct kvm_memory_slot *old,
+				   enum kvm_mr_change change)
 {
 }
 

arch/ia64/kvm/kvm-ia64.c

@@ -1591,7 +1591,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 		struct kvm_userspace_memory_region *mem,
-		struct kvm_memory_slot old)
+		const struct kvm_memory_slot *old,
+		enum kvm_mr_change change)
 {
 	return;
 }

arch/powerpc/include/asm/kvm_ppc.h

@@ -152,7 +152,7 @@ extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem);
 extern void kvmppc_core_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old);
+				const struct kvm_memory_slot *old);
 extern int kvm_vm_ioctl_get_smmu_info(struct kvm *kvm,
 				      struct kvm_ppc_smmu_info *info);
 extern void kvmppc_core_flush_memslot(struct kvm *kvm,

arch/powerpc/kvm/book3s_hv.c

@@ -1639,12 +1639,12 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
 				      struct kvm_userspace_memory_region *mem,
-				      struct kvm_memory_slot old)
+				      const struct kvm_memory_slot *old)
 {
 	unsigned long npages = mem->memory_size >> PAGE_SHIFT;
 	struct kvm_memory_slot *memslot;
 
-	if (npages && old.npages) {
+	if (npages && old->npages) {
 		/*
 		 * If modifying a memslot, reset all the rmap dirty bits.
 		 * If this is a new memslot, we don't need to do anything

arch/powerpc/kvm/book3s_pr.c

@@ -1283,7 +1283,7 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old)
+				const struct kvm_memory_slot *old)
 {
 }
 

arch/powerpc/kvm/booke.c

@@ -1531,7 +1531,7 @@ int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old)
+				const struct kvm_memory_slot *old)
 {
 }
 

arch/powerpc/kvm/powerpc.c

@@ -420,7 +420,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   struct kvm_userspace_memory_region *mem,
-				   struct kvm_memory_slot old)
+				   const struct kvm_memory_slot *old,
+				   enum kvm_mr_change change)
 {
 	kvmppc_core_commit_memory_region(kvm, mem, old);
 }

arch/s390/kvm/kvm-s390.c

@@ -1001,7 +1001,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old)
+				const struct kvm_memory_slot *old,
+				enum kvm_mr_change change)
 {
 	int rc;
 

arch/x86/kvm/x86.c

@@ -6935,16 +6935,17 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old)
+				const struct kvm_memory_slot *old,
+				enum kvm_mr_change change)
 {
 
-	int nr_mmu_pages = 0, npages = mem->memory_size >> PAGE_SHIFT;
+	int nr_mmu_pages = 0;
 
-	if ((mem->slot >= KVM_USER_MEM_SLOTS) && old.npages && !npages) {
+	if ((mem->slot >= KVM_USER_MEM_SLOTS) && (change == KVM_MR_DELETE)) {
 		int ret;
 
-		ret = vm_munmap(old.userspace_addr,
-				old.npages * PAGE_SIZE);
+		ret = vm_munmap(old->userspace_addr,
+				old->npages * PAGE_SIZE);
 		if (ret < 0)
 			printk(KERN_WARNING
 			       "kvm_vm_ioctl_set_memory_region: "
@@ -6961,13 +6962,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	 * Existing largepage mappings are destroyed here and new ones will
 	 * not be created until the end of the logging.
 	 */
-	if (npages && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES))
+	if ((change != KVM_MR_DELETE) && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES))
 		kvm_mmu_slot_remove_write_access(kvm, mem->slot);
 	/*
 	 * If memory slot is created, or moved, we need to clear all
 	 * mmio sptes.
 	 */
-	if (npages && old.base_gfn != mem->guest_phys_addr >> PAGE_SHIFT) {
+	if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
 		kvm_mmu_zap_all(kvm);
 		kvm_reload_remote_mmus(kvm);
 	}

include/linux/kvm_host.h

@@ -483,7 +483,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				enum kvm_mr_change change);
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem,
-				struct kvm_memory_slot old);
+				const struct kvm_memory_slot *old,
+				enum kvm_mr_change change);
 bool kvm_largepages_enabled(void);
 void kvm_disable_largepages(void);
 /* flush all memory translations */

virt/kvm/kvm_main.c

@@ -896,7 +896,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	old_memslots = install_new_memslots(kvm, slots, &new);
 
-	kvm_arch_commit_memory_region(kvm, mem, old);
+	kvm_arch_commit_memory_region(kvm, mem, &old, change);
 
 	kvm_free_physmem_slot(&old, &new);
 	kfree(old_memslots);