KVM: const-ify uses of struct kvm_userspace_memory_region

Architecture-specific helpers are not supposed to muck with
struct kvm_userspace_memory_region contents.  Add const to
enforce this.

In order to eliminate the only write in __kvm_set_memory_region,
the cleaning of deleted slots is pulled up from update_memslots
to __kvm_set_memory_region.
Reviewed-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/arm/kvm/mmu.c

@@ -1719,7 +1719,7 @@ int kvm_mmu_init(void)
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   const struct kvm_memory_slot *old,
 				   enum kvm_mr_change change)
 {
@@ -1734,7 +1734,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   enum kvm_mr_change change)
 {
 	hva_t hva = mem->userspace_addr;

arch/mips/kvm/mips.c

@@ -198,14 +198,14 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   enum kvm_mr_change change)
 {
 	return 0;
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   const struct kvm_memory_slot *old,
 				   enum kvm_mr_change change)
 {

arch/powerpc/include/asm/kvm_ppc.h

@@ -182,9 +182,9 @@ extern int kvmppc_core_create_memslot(struct kvm *kvm,
 				      unsigned long npages);
 extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				struct kvm_userspace_memory_region *mem);
+				const struct kvm_userspace_memory_region *mem);
 extern void kvmppc_core_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old);
 extern int kvm_vm_ioctl_get_smmu_info(struct kvm *kvm,
 				      struct kvm_ppc_smmu_info *info);
@@ -243,9 +243,9 @@ struct kvmppc_ops {
 	void (*flush_memslot)(struct kvm *kvm, struct kvm_memory_slot *memslot);
 	int (*prepare_memory_region)(struct kvm *kvm,
 				     struct kvm_memory_slot *memslot,
-				     struct kvm_userspace_memory_region *mem);
+				     const struct kvm_userspace_memory_region *mem);
 	void (*commit_memory_region)(struct kvm *kvm,
-				     struct kvm_userspace_memory_region *mem,
+				     const struct kvm_userspace_memory_region *mem,
 				     const struct kvm_memory_slot *old);
 	int (*unmap_hva)(struct kvm *kvm, unsigned long hva);
 	int (*unmap_hva_range)(struct kvm *kvm, unsigned long start,

arch/powerpc/kvm/book3s.c

@@ -757,13 +757,13 @@ void kvmppc_core_flush_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
 
 int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				struct kvm_userspace_memory_region *mem)
+				const struct kvm_userspace_memory_region *mem)
 {
 	return kvm->arch.kvm_ops->prepare_memory_region(kvm, memslot, mem);
 }
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old)
 {
 	kvm->arch.kvm_ops->commit_memory_region(kvm, mem, old);

arch/powerpc/kvm/book3s_hv.c

@@ -2376,13 +2376,13 @@ static int kvmppc_core_create_memslot_hv(struct kvm_memory_slot *slot,
 
 static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
 					struct kvm_memory_slot *memslot,
-					struct kvm_userspace_memory_region *mem)
+					const struct kvm_userspace_memory_region *mem)
 {
 	return 0;
 }
 
 static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old)
 {
 	unsigned long npages = mem->memory_size >> PAGE_SHIFT;

arch/powerpc/kvm/book3s_pr.c

@@ -1573,13 +1573,13 @@ static void kvmppc_core_flush_memslot_pr(struct kvm *kvm,
 
 static int kvmppc_core_prepare_memory_region_pr(struct kvm *kvm,
 					struct kvm_memory_slot *memslot,
-					struct kvm_userspace_memory_region *mem)
+					const struct kvm_userspace_memory_region *mem)
 {
 	return 0;
 }
 
 static void kvmppc_core_commit_memory_region_pr(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old)
 {
 	return;

arch/powerpc/kvm/booke.c

@@ -1784,13 +1784,13 @@ int kvmppc_core_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				      struct kvm_memory_slot *memslot,
-				      struct kvm_userspace_memory_region *mem)
+				      const struct kvm_userspace_memory_region *mem)
 {
 	return 0;
 }
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old)
 {
 }

arch/powerpc/kvm/powerpc.c

@@ -595,14 +595,14 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   enum kvm_mr_change change)
 {
 	return kvmppc_core_prepare_memory_region(kvm, memslot, mem);
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   const struct kvm_memory_slot *old,
 				   enum kvm_mr_change change)
 {

arch/s390/kvm/kvm-s390.c

@@ -2582,7 +2582,7 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 /* Section: memory related */
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
-				   struct kvm_userspace_memory_region *mem,
+				   const struct kvm_userspace_memory_region *mem,
 				   enum kvm_mr_change change)
 {
 	/* A few sanity checks. We can have memory slots which have to be
@@ -2600,7 +2600,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
 				enum kvm_mr_change change)
 {

arch/x86/kvm/x86.c

@@ -7700,7 +7700,7 @@ void kvm_arch_memslots_updated(struct kvm *kvm)
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
 	/*
@@ -7778,7 +7778,7 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
 				enum kvm_mr_change change)
 {

include/linux/kvm_host.h

@@ -501,9 +501,9 @@ enum kvm_mr_change {
 };
 
 int kvm_set_memory_region(struct kvm *kvm,
-			  struct kvm_userspace_memory_region *mem);
+			  const struct kvm_userspace_memory_region *mem);
 int __kvm_set_memory_region(struct kvm *kvm,
-			    struct kvm_userspace_memory_region *mem);
+			    const struct kvm_userspace_memory_region *mem);
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 			   struct kvm_memory_slot *dont);
 int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
@@ -511,10 +511,10 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 void kvm_arch_memslots_updated(struct kvm *kvm);
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change);
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-				struct kvm_userspace_memory_region *mem,
+				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
 				enum kvm_mr_change change);
 bool kvm_largepages_enabled(void);

virt/kvm/kvm_main.c

@@ -676,8 +676,6 @@ static void update_memslots(struct kvm_memslots *slots,
 	WARN_ON(mslots[i].id != id);
 	if (!new->npages) {
 		WARN_ON(!mslots[i].npages);
-		new->base_gfn = 0;
-		new->flags = 0;
 		if (mslots[i].npages)
 			slots->used_slots--;
 	} else {
@@ -717,7 +715,7 @@ static void update_memslots(struct kvm_memslots *slots,
 	slots->id_to_index[mslots[i].id] = i;
 }
 
-static int check_memory_region_flags(struct kvm_userspace_memory_region *mem)
+static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
 {
 	u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
@@ -767,7 +765,7 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
  * Must be called holding kvm->slots_lock for write.
  */
 int __kvm_set_memory_region(struct kvm *kvm,
-			    struct kvm_userspace_memory_region *mem)
+			    const struct kvm_userspace_memory_region *mem)
 {
 	int r;
 	gfn_t base_gfn;
@@ -806,9 +804,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (npages > KVM_MEM_MAX_NR_PAGES)
 		goto out;
 
-	if (!npages)
-		mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
-
 	new = old = *slot;
 
 	new.id = mem->slot;
@@ -834,10 +829,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
 				goto out;
 			}
 		}
-	} else if (old.npages) {
+	} else {
+		if (!old.npages)
+			goto out;
+
 		change = KVM_MR_DELETE;
-	} else /* Modify a non-existent slot: disallowed. */
-		goto out;
+		new.base_gfn = 0;
+		new.flags = 0;
+	}
 
 	if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
 		/* Check for overlaps */
@@ -944,7 +943,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
 
 int kvm_set_memory_region(struct kvm *kvm,
-			  struct kvm_userspace_memory_region *mem)
+			  const struct kvm_userspace_memory_region *mem)
 {
 	int r;
 
@@ -960,6 +959,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 {
 	if (mem->slot >= KVM_USER_MEM_SLOTS)
 		return -EINVAL;
+
 	return kvm_set_memory_region(kvm, mem);
 }