Re: [PATCH RFC 1/9] KVM: Fixup kvm_log_clear_one_slot() ioctl return check

[Peter Xu]

On Wed, Feb 05, 2020 at 09:17:41AM -0500, Peter Xu wrote:
> kvm_vm_ioctl() handles the errno trick already for ioctl() on
> returning -1 for errors.  Fix this.
> 
> Signed-off-by: Peter Xu <address@hidden>
> ---
>  accel/kvm/kvm-all.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index c111312dfd..4be3cd2352 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -688,14 +688,13 @@ static int kvm_log_clear_one_slot(KVMSlot *mem, int 
> as_id, uint64_t start,
>      d.num_pages = bmap_npages;
>      d.slot = mem->slot | (as_id << 16);
>  
> -    if (kvm_vm_ioctl(s, KVM_CLEAR_DIRTY_LOG, &d) == -1) {
> -        ret = -errno;
> +    ret = kvm_vm_ioctl(s, KVM_CLEAR_DIRTY_LOG, &d);

Dave raised a question offlist when comparing with KVM_GET_DIRTY_LOG,
regarding 50212d6346 ("Revert "fix return check for KVM_GET_DIRTY_LOG
ioctl"", 2014-04-14) where we wanted to allow KVM_GET_DIRTY_LOG to
fail for some cases.  I didn't find any context of that, and from the
first glance I don't understand why and when we'll get -ENOENT during
sync dirty log (we should have BQL held, so I don't know why a memslot
can be gone underneath).  Anyone knows more?

CCing Peter Maydell and Michael Tokarev too.

> +    if (ret) {
>          error_report("%s: KVM_CLEAR_DIRTY_LOG failed, slot=%d, "
>                       "start=0x%"PRIx64", size=0x%"PRIx32", errno=%d",
>                       __func__, d.slot, (uint64_t)d.first_page,
>                       (uint32_t)d.num_pages, ret);
>      } else {
> -        ret = 0;
>          trace_kvm_clear_dirty_log(d.slot, d.first_page, d.num_pages);
>      }
>  
> -- 
> 2.24.1
> 

-- 
Peter Xu