From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1edaf7-00075Q-9e for qemu-devel@nongnu.org; Mon, 22 Jan 2018 06:53:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1edaf4-0001pU-6f for qemu-devel@nongnu.org; Mon, 22 Jan 2018 06:53:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40420) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1edaf3-0001ol-Tu for qemu-devel@nongnu.org; Mon, 22 Jan 2018 06:53:14 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8304E83F42 for ; Mon, 22 Jan 2018 11:53:11 +0000 (UTC) References: <1515924416-9266-1-git-send-email-ghammer@redhat.com> <1515924416-9266-3-git-send-email-ghammer@redhat.com> From: Michal Privoznik Message-ID: <584986dc-eeb6-4cfe-8ee3-330b17c55c09@redhat.com> Date: Mon, 22 Jan 2018 12:53:04 +0100 MIME-Version: 1.0 In-Reply-To: <1515924416-9266-3-git-send-email-ghammer@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/3] virtio: postpone the execution of event_notifier_cleanup function List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gal Hammer , qemu-devel@nongnu.org Cc: mst@redhat.com On 01/14/2018 11:06 AM, Gal Hammer wrote: > Use the EventNotifier's cleanup callback function to execute the > event_notifier_cleanup function after kvm unregistered the eventfd. > > This change supports running the virtio_bus_set_host_notifier > function inside a memory region transaction. Otherwise, a closed > fd is sent to kvm, which results in a failure. > > Signed-off-by: Gal Hammer > --- > accel/kvm/kvm-all.c | 4 ++++ > hw/virtio/virtio-bus.c | 19 +++++++++++-------- > 2 files changed, 15 insertions(+), 8 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index f290f48..071f4f5 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -812,6 +812,10 @@ static void kvm_mem_ioeventfd_del(MemoryListener *listener, > if (r < 0) { > abort(); > } > + > + if (e->cleanup) { > + e->cleanup(e); > + } > } > > static void kvm_io_ioeventfd_add(MemoryListener *listener, > diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c > index 3042232..8106346 100644 > --- a/hw/virtio/virtio-bus.c > +++ b/hw/virtio/virtio-bus.c > @@ -256,6 +256,15 @@ bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus) > return k->ioeventfd_assign && k->ioeventfd_enabled(proxy); > } > > +static void virtio_bus_cleanup_event_notifier(EventNotifier *notifier) > +{ > + /* Test and clear notifier after disabling event, > + * in case poll callback didn't have time to run. > + */ > + virtio_queue_host_notifier_read(notifier); > + event_notifier_cleanup(notifier); > +} > + > /* > * This function switches ioeventfd on/off in the device. > * The caller must set or clear the handlers for the EventNotifier. > @@ -283,19 +292,13 @@ int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign) > r = k->ioeventfd_assign(proxy, notifier, n, true); > if (r < 0) { > error_report("%s: unable to assign ioeventfd: %d", __func__, r); > - goto cleanup_event_notifier; > + virtio_bus_cleanup_event_notifier(notifier); > } > - return 0; > } else { > + notifier->cleanup = virtio_bus_cleanup_event_notifier; > k->ioeventfd_assign(proxy, notifier, n, false); > } > > -cleanup_event_notifier: > - /* Test and clear notifier after disabling event, > - * in case poll callback didn't have time to run. > - */ > - virtio_queue_host_notifier_read(notifier); > - event_notifier_cleanup(notifier); > return r; > } > > This causes abort() to me: Thread 7 "CPU 3/KVM" received signal SIGABRT, Aborted. [Switching to Thread 0x7f78fa1f4700 (LWP 13737)] __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51 51 } __GI_raise 7 # bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51 #1 0x00007f7a09ff5c1a in __GI_abort () at abort.c:89 #2 0x000055f2a70bce9d in kvm_io_ioeventfd_del (listener=0x55f2a7d19200 , section=0x7f78fa1f10f0, match_data=true, data=0, e=0x7f79fc81f080) at /home/zippy/work/qemu/qemu.git/accel/kvm/kvm-all.c:852 #3 0x000055f2a70a6fac in address_space_add_del_ioeventfds (as=0x55f2a7e86620 , fds_new=0x7f78e40b9e80, fds_new_nb=2, fds_old=0x7f78e40b9f10, fds_old_nb=3) at /home/zippy/work/qemu/qemu.git/memory.c:832 #4 0x000055f2a70a744d in address_space_update_ioeventfds (as=0x55f2a7e86620 ) at /home/zippy/work/qemu/qemu.git/memory.c:895 #5 0x000055f2a70a7f04 in memory_region_transaction_commit () at /home/zippy/work/qemu/qemu.git/memory.c:1097 #6 0x000055f2a70ab0d1 in memory_region_del_eventfd (mr=0x55f2a9422250, addr=16, size=2, match_data=true, data=0, e=0x7f79fc81f080) at /home/zippy/work/qemu/qemu.git/memory.c:2273 #7 0x000055f2a7411f18 in virtio_pci_ioeventfd_assign (d=0x55f2a9421970, notifier=0x7f79fc81f080, n=0, assign=false) at hw/virtio/virtio-pci.c:280 #8 0x000055f2a7418e6f in virtio_bus_set_host_notifier (bus=0x55f2a9429a68, n=0, assign=false) at hw/virtio/virtio-bus.c:299 #9 0x000055f2a710236a in virtio_scsi_dataplane_stop (vdev=0x55f2a9429ae0) at /home/zippy/work/qemu/qemu.git/hw/scsi/virtio-scsi-dataplane.c:215 #10 0x000055f2a7418bb3 in virtio_bus_stop_ioeventfd (bus=0x55f2a9429a68) at hw/virtio/virtio-bus.c:246 #11 0x000055f2a7411f63 in virtio_pci_stop_ioeventfd (proxy=0x55f2a9421970) at hw/virtio/virtio-pci.c:294 #12 0x000055f2a74144ab in virtio_pci_common_write (opaque=0x55f2a9421970, addr=20, val=0, size=1) at hw/virtio/virtio-pci.c:1262 #13 0x000055f2a70a6016 in memory_region_write_accessor (mr=0x55f2a9422340, addr=20, value=0x7f78fa1f1558, size=1, shift=0, mask=255, attrs=...) at /home/zippy/work/qemu/qemu.git/memory.c:560 #14 0x000055f2a70a622e in access_with_adjusted_size (addr=20, value=0x7f78fa1f1558, size=1, access_size_min=1, access_size_max=4, access_fn=0x55f2a70a5f2c , mr=0x55f2a9422340, attrs=...) at /home/zippy/work/qemu/qemu.git/memory.c:627 #15 0x000055f2a70a8eb0 in memory_region_dispatch_write (mr=0x55f2a9422340, addr=20, data=0, size=1, attrs=...) at /home/zippy/work/qemu/qemu.git/memory.c:1503 #16 0x000055f2a7058b2b in flatview_write_continue (fv=0x7f78e405eba0, addr=4269834260, attrs=..., buf=0x7f7a26c36028 "", len=1, addr1=20, l=1, mr=0x55f2a9422340) at /home/zippy/work/qemu/qemu.git/exec.c:3038 #17 0x000055f2a7058c79 in flatview_write (fv=0x7f78e405eba0, addr=4269834260, attrs=..., buf=0x7f7a26c36028 "", len=1) at /home/zippy/work/qemu/qemu.git/exec.c:3083 #18 0x000055f2a7059050 in flatview_rw (fv=0x7f78e405eba0, addr=4269834260, attrs=..., buf=0x7f7a26c36028 "", len=1, is_write=true) at /home/zippy/work/qemu/qemu.git/exec.c:3192 #19 0x000055f2a7059108 in address_space_rw (as=0x55f2a7e86680 , addr=4269834260, attrs=..., buf=0x7f7a26c36028 "", len=1, is_write=true) at /home/zippy/work/qemu/qemu.git/exec.c:3202 #20 0x000055f2a70bf42c in kvm_cpu_exec (cpu=0x55f2a850cda0) at /home/zippy/work/qemu/qemu.git/accel/kvm/kvm-all.c:1941 #21 0x000055f2a708d455 in qemu_kvm_cpu_thread_fn (arg=0x55f2a850cda0) at /home/zippy/work/qemu/qemu.git/cpus.c:1196 #22 0x000055f2a75ce829 in qemu_thread_start (args=0x55f2a852e260) at util/qemu-thread-posix.c:504 #23 0x00007f7a0a375887 in start_thread (arg=0x7f78fa1f4700) at pthread_create.c:456 #24 0x00007f7a0a0b7d4f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 __GI_raise 7 # up #1 0x00007f7a09ff5c1a in __GI_abort () at abort.c:89 89 raise (SIGABRT); __GI_abort 7 # #2 0x000055f2a70bce9d in kvm_io_ioeventfd_del (listener=0x55f2a7d19200 , section=0x7f78fa1f10f0, match_data=true, data=0, e=0x7f79fc81f080) at /home/zippy/work/qemu/qemu.git/accel/kvm/kvm-all.c:852 852 abort(); kvm_io_ioeventfd_del 7 # p *e $1 = {rfd = -1, wfd = -1, cleanup = 0x0} I think the problem is that event_notifier_cleanup() is called before kvm_io_ioeventfd_del() and both are called over the same EventNotifier. This is supported by another data I was able to collect in a different run: Thread 4 "CPU 0/KVM" hit Breakpoint 1, event_notifier_cleanup (e=0x7fc6ac26f080) at util/event_notifier-posix.c:83 83 if (e->rfd != e->wfd) { event_notifier_cleanup 4 # p *e $1 = {rfd = 48, wfd = 48, cleanup = 0x55c91c76ac87 } event_notifier_cleanup 4 # c Continuing. Thread 4 "CPU 0/KVM" received signal SIGABRT, Aborted. __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51 51 } __GI_raise 4 # up #1 0x00007fc6b9a45c1a in __GI_abort () at abort.c:89 89 raise (SIGABRT); __GI_abort 4 # #2 0x000055c91c40ee9d in kvm_io_ioeventfd_del (listener=0x55c91d06b200 , section=0x7fc5ab1fa0f0, match_data=true, data=0, e=0x7fc6ac26f080) at /home/zippy/work/qemu/qemu.git/accel/kvm/kvm-all.c:852 852 abort(); kvm_io_ioeventfd_del 4 # p *e $2 = {rfd = -1, wfd = -1, cleanup = 0x0} So I drafted dirty workaround: index 071f4f57c0..bf15344533 100644 --- i/accel/kvm/kvm-all.c +++ w/accel/kvm/kvm-all.c @@ -845,6 +845,9 @@ static void kvm_io_ioeventfd_del(MemoryListener *listener, int fd = event_notifier_get_fd(e); int r; + if (fd == -1) + return; + r = kvm_set_ioeventfd_pio(fd, section->offset_within_address_space, data, false, int128_get64(section->size), match_data); But this time I'm getting following error: kvm_io_ioeventfd_add: error adding ioeventfd: File exists __GI_raise 7 # up #1 0x00007f3ccd579c1a in __GI_abort () at abort.c:89 89 raise (SIGABRT); __GI_abort 7 # #2 0x000055c68ac84e08 in kvm_io_ioeventfd_add (listener=0x55c68b8e1200 , section=0x7f3bbd7f1090, match_data=true, data=0, e=0x7f3bbcf8d080) at /home/zippy/work/qemu/qemu.git/accel/kvm/kvm-all.c:835 835 abort(); kvm_io_ioeventfd_add 7 # p *e $1 = {rfd = 48, wfd = 48, cleanup = 0x0} Michal