KVM: Refactor error handling for setting memory region

Replace a big pile o' gotos with returns to make it more obvious what
error code is being returned, and to prepare for refactoring the
functional, i.e. post-checks, portion of __kvm_set_memory_region().

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 33fb93d41ba1d848b771653126dccbe0ac84a829..f5719ce7e2d5ec8c1a019e33fe933906630ede9f 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1005,34 +1005,33 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
        r = check_memory_region_flags(mem);
        if (r)
-               goto out;
+               return r;
 
-       r = -EINVAL;
        as_id = mem->slot >> 16;
        id = (u16)mem->slot;
 
        /* General sanity checks */
        if (mem->memory_size & (PAGE_SIZE - 1))
-               goto out;
+               return -EINVAL;
        if (mem->guest_phys_addr & (PAGE_SIZE - 1))
-               goto out;
+               return -EINVAL;
        /* We can read the guest memory with __xxx_user() later on. */
        if ((id < KVM_USER_MEM_SLOTS) &&
            ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
             !access_ok((void __user *)(unsigned long)mem->userspace_addr,
                        mem->memory_size)))
-               goto out;
+               return -EINVAL;
        if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
-               goto out;
+               return -EINVAL;
        if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
-               goto out;
+               return -EINVAL;
 
        slot = id_to_memslot(__kvm_memslots(kvm, as_id), id);
        base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
        npages = mem->memory_size >> PAGE_SHIFT;
 
        if (npages > KVM_MEM_MAX_NR_PAGES)
-               goto out;
+               return -EINVAL;
 
        new = old = *slot;
 
@@ -1049,20 +1048,18 @@ int __kvm_set_memory_region(struct kvm *kvm,
                        if ((new.userspace_addr != old.userspace_addr) ||
                            (npages != old.npages) ||
                            ((new.flags ^ old.flags) & KVM_MEM_READONLY))
-                               goto out;
+                               return -EINVAL;
 
                        if (base_gfn != old.base_gfn)
                                change = KVM_MR_MOVE;
                        else if (new.flags != old.flags)
                                change = KVM_MR_FLAGS_ONLY;
-                       else { /* Nothing to change. */
-                               r = 0;
-                               goto out;
-                       }
+                       else /* Nothing to change. */
+                               return 0;
                }
        } else {
                if (!old.npages)
-                       goto out;
+                       return -EINVAL;
 
                change = KVM_MR_DELETE;
                new.base_gfn = 0;
@@ -1071,29 +1068,29 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
        if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
                /* Check for overlaps */
-               r = -EEXIST;
                kvm_for_each_memslot(slot, __kvm_memslots(kvm, as_id)) {
                        if (slot->id == id)
                                continue;
                        if (!((base_gfn + npages <= slot->base_gfn) ||
                              (base_gfn >= slot->base_gfn + slot->npages)))
-                               goto out;
+                               return -EEXIST;
                }
        }
 
-       r = -ENOMEM;
-
        /* Allocate/free page dirty bitmap as needed */
        if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
                new.dirty_bitmap = NULL;
        else if (!new.dirty_bitmap) {
-               if (kvm_create_dirty_bitmap(&new) < 0)
-                       goto out;
+               r = kvm_create_dirty_bitmap(&new);
+               if (r)
+                       return r;
        }
 
        slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
-       if (!slots)
+       if (!slots) {
+               r = -ENOMEM;
                goto out_bitmap;
+       }
        memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
 
        if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
@@ -1144,7 +1141,6 @@ out_slots:
 out_bitmap:
        if (new.dirty_bitmap && !old.dirty_bitmap)
                kvm_destroy_dirty_bitmap(&new);
-out:
        return r;
 }
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);