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Date: Fri, 11 Apr 2014 21:50:40 -0400
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Subject: Re: [Qemu-devel] [PATCH for-2.0] kvm_physical_sync_dirty_bitmap:
 ignore ENOENT from kvm_vm_ioctl
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To: Michael Tokarev <mjt@tls.msk.ru>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Serge Hallyn <serge.hallyn@ubuntu.com>, Mario Smarduch <m.smarduch@samsung.com>

Il 11/04/2014 04:31, Michael Tokarev ha scritto:
> ENOENT means the kernel has an empty dirty bitmap for this
> slot.  Don't abort in that case.  This appears to solve
> the bug reported at
>
> https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1303926
>
> which first showed up with commit b533f658a98325d: fix return
> check for KVM_GET_DIRTY_LOG ioctl
>
> Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> ---
>  kvm-all.c |   10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index cd4111d..47fa948 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -441,13 +441,19 @@ static int kvm_physical_sync_dirty_bitmap(MemoryRegionSection *section)
>
>          d.slot = mem->slot;
>
> -        if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) < 0) {
> +        ret = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
> +        if (ret >= 0) {
> +            /* regular case, process returned bitmap */
> +            kvm_get_dirty_pages_log_range(section, d.dirty_bitmap);
> +        } else if (ret == -ENOENT) {
> +            /* kernel does not have dirty bitmap in this slot */
> +            ret = 0;
> +        } else {
>              DPRINTF("ioctl failed %d\n", errno);
>              ret = -1;
>              break;
>          }
>
> -        kvm_get_dirty_pages_log_range(section, d.dirty_bitmap);
>          start_addr = mem->start_addr + mem->memory_size;
>      }
>      g_free(d.dirty_bitmap);
>

I'd rather revert b533f658a98325d instead.

Paolo