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[83.42.66.122]) by smtp.gmail.com with ESMTPSA id j23sm4222231wmo.26.2021.07.23.00.34.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 Jul 2021 00:34:50 -0700 (PDT) Subject: Re: [PATCH 1/2] qxl: remove assert in qxl_pre_save. To: Gerd Hoffmann References: <20210721093347.338536-1-kraxel@redhat.com> <20210721093347.338536-2-kraxel@redhat.com> <20210723063233.ktjex5knfgz77pbq@sirius.home.kraxel.org> <13c8a40f-a879-a981-12f0-36a5289b39b1@redhat.com> <20210723065527.glqc44gyga2lnqyc@sirius.home.kraxel.org> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <0196b381-47ca-fb37-d809-e2a25f3c677e@redhat.com> Date: Fri, 23 Jul 2021 09:34:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210723065527.glqc44gyga2lnqyc@sirius.home.kraxel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.472, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.203, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: armbru@redhat.com, "Dr. David Alan Gilbert" , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 >>>>> --- >>>>> 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").