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    Subject[PATCH v2 07/15] KVM: Refactor error handling for setting memory region
    Date
    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>
    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    ---
    virt/kvm/kvm_main.c | 40 ++++++++++++++++++----------------------
    1 file changed, 18 insertions(+), 22 deletions(-)

    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 26151e2e3365..40e27ffaf29a 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -930,34 +930,33 @@ 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;

    @@ -974,20 +973,18 @@ 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;
    @@ -996,29 +993,29 @@ 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)) {
    @@ -1069,7 +1066,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
    out_bitmap:
    if (new.dirty_bitmap && !old.dirty_bitmap)
    kvm_destroy_dirty_bitmap(&new);
    -out:
    return r;
    }
    EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
    --
    2.22.0
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