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From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: armbru@redhat.com, "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH 1/2] qxl: remove assert in qxl_pre_save.
Date: Fri, 23 Jul 2021 09:34:49 +0200	[thread overview]
Message-ID: <0196b381-47ca-fb37-d809-e2a25f3c677e@redhat.com> (raw)
In-Reply-To: <20210723065527.glqc44gyga2lnqyc@sirius.home.kraxel.org>

On 7/23/21 8:55 AM, Gerd Hoffmann wrote:
> On Fri, Jul 23, 2021 at 08:47:09AM +0200, Philippe Mathieu-Daudé wrote:
>> On 7/23/21 8:32 AM, Gerd Hoffmann wrote:
>>> On Thu, Jul 22, 2021 at 03:44:54PM +0100, Dr. David Alan Gilbert wrote:
>>>> * Gerd Hoffmann (kraxel@redhat.com) wrote:
>>>>> Since commit 551dbd0846d2 ("migration: check pre_save return in
>>>>> vmstate_save_state") the pre_save hook can fail.  So lets finally
>>>>> use that to drop the guest-triggerable assert in qxl_pre_save().
>>>>>
>>>>> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
>>>>> ---
>>>>>  hw/display/qxl.c | 4 +++-
>>>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/hw/display/qxl.c b/hw/display/qxl.c
>>>>> index 84f99088e0a0..3867b94fe236 100644
>>>>> --- a/hw/display/qxl.c
>>>>> +++ b/hw/display/qxl.c
>>>>> @@ -2283,7 +2283,9 @@ static int qxl_pre_save(void *opaque)
>>>>>      } else {
>>>>>          d->last_release_offset = (uint8_t *)d->last_release - ram_start;
>>>>>      }
>>>>> -    assert(d->last_release_offset < d->vga.vram_size);
>>>>> +    if (d->last_release_offset < d->vga.vram_size) {
>>>>> +        return 1;
>>>>
>>>> It would be great if there was an error_report or something there
>>>> so that we get some idea of what happened.
>>>
>>> Hmm.  Strictly speaking qemu_log_mask(LOG_GUEST_ERROR, "..."); would be
>>> the correct approach here, but I guess that wouldn't help much for
>>> trouble-shooting as the message would only show up with "-d
>>> guest_errors".  So better make that error_report("...") ?
>>
>> It depends who is interested in such errors.
> 
> Migration fails and you want know why.
> 
> Reason migration fails is the guest violates qxl specs (which doesn't
> cause actual problems unless you want migrate the guest).

Then I agree error_report() is better ("Report an error to the current
monitor if we have one, else stderr").



  reply	other threads:[~2021-07-23  7:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21  9:33 [PATCH 0/2] qxl: remove assert and migration blocker Gerd Hoffmann
2021-07-21  9:33 ` [PATCH 1/2] qxl: remove assert in qxl_pre_save Gerd Hoffmann
2021-07-21 10:43   ` Marc-André Lureau
2021-07-22 14:44   ` Dr. David Alan Gilbert
2021-07-23  6:32     ` Gerd Hoffmann
2021-07-23  6:47       ` Philippe Mathieu-Daudé
2021-07-23  6:55         ` Gerd Hoffmann
2021-07-23  7:34           ` Philippe Mathieu-Daudé [this message]
2021-07-23  8:42             ` Markus Armbruster
2021-07-23  9:46               ` Gerd Hoffmann
2021-07-21  9:33 ` [PATCH 2/2] Revert "qxl: add migration blocker to avoid pre-save assert" Gerd Hoffmann
2021-07-21 10:44   ` Marc-André Lureau
2021-07-21 14:15   ` Markus Armbruster

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