Hi
On Mon, Jan 22, 2018 at 12:53 PM, Michal Privoznik <mpriv...@redhat.com> wrote:
> 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 <gham...@redhat.com>
>> ---
>> 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
> <kvm_io_listener>, 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
> <address_space_io>, 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
> <address_space_io>) 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 <memory_region_write_accessor>, 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
> <address_space_memory>, 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
> <kvm_io_listener>, 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
> <virtio_bus_cleanup_event_notifier>}
> 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
> <kvm_io_listener>, 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
> <kvm_io_listener>, 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}
>
I was about to report the same error when booting an uefi guest, I
bisected down to the same first bad commit.
Thanks Michal
--
Marc-André Lureau
