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Tsirkin" To: Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Subject: Re: [PATCH] hw/virtio: Update vring after modifying its queue size Message-ID: <20210830171528-mutt-send-email-mst@kernel.org> References: <20210825224256.1750286-1-philmd@redhat.com> <6824eed8-30e6-dbbf-4a4f-92e394c5430c@redhat.com> MIME-Version: 1.0 In-Reply-To: <6824eed8-30e6-dbbf-4a4f-92e394c5430c@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.391, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, WEIRD_PORT=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: Jason Wang , Cornelia Huck , Li Qiang , qemu-devel , Qiuhao Li , Alexander Bulekov , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Aug 26, 2021 at 10:40:47AM +0200, Philippe Mathieu-Daudé wrote: > On 8/26/21 5:28 AM, Jason Wang wrote: > > On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé > > wrote: > >> > >> When a ring queue size is modified, we need to call > >> virtio_queue_update_rings() to re-init the memory region > >> caches. Otherwise the region might have outdated memory > >> size, and later load/store access might trigger an > >> assertion, such: > >> > >> qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *): > >> Assertion `addr < cache->len && 2 <= cache->len - addr' failed. > >> Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted. > >> 0x00007ffff4d312a2 in raise () from /lib64/libc.so.6 > >> (gdb) bt > >> #1 0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6 > >> #4 0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30 > >> #5 0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67 > >> #6 0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166 > >> #7 0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326 > >> #8 0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332 > >> #9 0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471 > >> #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523 > >> #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565 > >> #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100 > >> #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363 > >> #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369 > >> #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492 > >> > >> Reported-by: Qiuhao Li > >> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout") > >> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302 > >> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510 > >> Signed-off-by: Philippe Mathieu-Daudé > >> --- > >> hw/virtio/virtio.c | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > >> index 874377f37a7..04ffe5f420e 100644 > >> --- a/hw/virtio/virtio.c > >> +++ b/hw/virtio/virtio.c > >> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num) > >> return; > >> } > >> vdev->vq[n].vring.num = num; > >> + virtio_queue_update_rings(vdev, n); > >> } > >> > > > > Spec said: > > > > " > > The driver MUST configure the other virtqueue fields before enabling > > the virtqueue with queue_enable. > > " > > > > So I think we should forbid the num to be changed if the virtqueue is ready? > > Alright. virtio_pci_common_write() doesn't report errors although. It can't - just log guest error and ignore. Maybe set needs_reset ... -- MST