On Thu, Jun 27, 2024 at 4:55 PM Michael S. Tsirkin <m...@redhat.com> wrote:
>
> On Thu, Jun 27, 2024 at 04:40:33PM +0800, Cindy Lu wrote:
> > On Wed, Jun 26, 2024 at 3:45 PM Michael S. Tsirkin <m...@redhat.com> wrote:
> > >
> > > On Wed, Jun 26, 2024 at 10:44:31AM +0800, Cindy Lu wrote:
> > > > The crash was reported in MAC OS and NixOS, here is the link for this
> > > > bug
> > > > https://gitlab.com/qemu-project/qemu/-/issues/2334
> > > > https://gitlab.com/qemu-project/qemu/-/issues/2321
> > > >
> > > > The root cause is the function virtio_pci_set_guest_notifiers() was not
> > > > called
> > > > in the virtio_input device.So the vector_irqfd was not initialized
> > > >
> > > > So the fix is add the check for vector_irqfd.
> > > >
> > > > Change in V3
> > >
> > > Changelog belongs after ---
> > >
> > thanks micheal, will fix this
> > > > 1) Move the vector_irqfd check to virtio_pci_get_notifier().
> > > > The function virtio_pci_get_notifier() can also be used while
> > > > vdev->status
> > > > is not VIRTIO_CONFIG_S_DRIVER_OK. In that case, the vector_irqfd could
> > > > be NULL,
> > > > so also add the status check here.
> > > > 2) Add the return value check for kvm_virtio_pci_vector_use_one().
> > > > Since the return value of function virtio_pci_set_vector() is void,
> > > > just add the error message here.
> > > >
> > > > This fix is verified in vyatta,MacOS,NixOS,fedora system.
> > > >
> > > > The bt tree for this bug is:
> > > > Thread 6 "CPU 0/KVM" received signal SIGSEGV, Segmentation fault.
> > > > [Switching to Thread 0x7c817be006c0 (LWP 1269146)]
> > > > kvm_virtio_pci_vq_vector_use () at
> > > > ../qemu-9.0.0/hw/virtio/virtio-pci.c:817
> > > > 817 if (irqfd->users == 0) {
> > > > (gdb) thread apply all bt
> > > > ...
> > > > Thread 6 (Thread 0x7c817be006c0 (LWP 1269146) "CPU 0/KVM"):
> > > > 0 kvm_virtio_pci_vq_vector_use () at
> > > > ../qemu-9.0.0/hw/virtio/virtio-pci.c:817
> > > > 1 kvm_virtio_pci_vector_use_one () at
> > > > ../qemu-9.0.0/hw/virtio/virtio-pci.c:893
> > > > 2 0x00005983657045e2 in memory_region_write_accessor () at
> > > > ../qemu-9.0.0/system/memory.c:497
> > > > 3 0x0000598365704ba6 in access_with_adjusted_size () at
> > > > ../qemu-9.0.0/system/memory.c:573
> > > > 4 0x0000598365705059 in memory_region_dispatch_write () at
> > > > ../qemu-9.0.0/system/memory.c:1528
> > > > 5 0x00005983659b8e1f in flatview_write_continue_step.isra.0 () at
> > > > ../qemu-9.0.0/system/physmem.c:2713
> > > > 6 0x000059836570ba7d in flatview_write_continue () at
> > > > ../qemu-9.0.0/system/physmem.c:2743
> > > > 7 flatview_write () at ../qemu-9.0.0/system/physmem.c:2774
> > > > 8 0x000059836570bb76 in address_space_write () at
> > > > ../qemu-9.0.0/system/physmem.c:2894
> > > > 9 0x0000598365763afe in address_space_rw () at
> > > > ../qemu-9.0.0/system/physmem.c:2904
> > > > 10 kvm_cpu_exec () at ../qemu-9.0.0/accel/kvm/kvm-all.c:2917
> > > > 11 0x000059836576656e in kvm_vcpu_thread_fn () at
> > > > ../qemu-9.0.0/accel/kvm/kvm-accel-ops.c:50
> > > > 12 0x0000598365926ca8 in qemu_thread_start () at
> > > > ../qemu-9.0.0/util/qemu-thread-posix.c:541
> > > > 13 0x00007c8185bcd1cf in ??? () at /usr/lib/libc.so.6
> > > > 14 0x00007c8185c4e504 in clone () at /usr/lib/libc.so.6
> > > >
> > > > Fixes: 2ce6cff94d ("virtio-pci: fix use of a released vector")
> > > > Cc: qemu-sta...@nongnu.org
> > > >
> > >
> > > all trailers including s.o.b. should be together, with no empty lines
> > >
> > will change this
> > > > Signed-off-by: Cindy Lu <l...@redhat.com>
> > > > ---
> > > > hw/virtio/virtio-pci.c | 9 ++++++++-
> > > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > > > index b1d02f4b3d..87307b9061 100644
> > > > --- a/hw/virtio/virtio-pci.c
> > > > +++ b/hw/virtio/virtio-pci.c
> > > > @@ -860,6 +860,11 @@ static int virtio_pci_get_notifier(VirtIOPCIProxy
> > > > *proxy, int queue_no,
> > > > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> > > > VirtQueue *vq;
> > > >
> > > > + if ((proxy->vector_irqfd == NULL) &&
> > >
> > > Preferable:
> > > if (!proxy->vector_irqfd &&
> > >
> > > and brackets not really needed here
> > >
> > >
> > > > + (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> > >
> > > brackets not really needed here
> > >
> > sure, will fix this
> > > > + return -1;
> > > > + }
> > > > +
> > > > if (queue_no == VIRTIO_CONFIG_IRQ_IDX) {
> > > > *n = virtio_config_get_guest_notifier(vdev);
> > > > *vector = vdev->config_vector;
> > > > @@ -1452,7 +1457,9 @@ static void virtio_pci_set_vector(VirtIODevice
> > > > *vdev,
> > > > }
> > > > /* If the new vector changed need to set it up. */
> > > > if (kvm_irqfd && new_vector != VIRTIO_NO_VECTOR) {
> > > > - kvm_virtio_pci_vector_use_one(proxy, queue_no);
> > > > + if (kvm_virtio_pci_vector_use_one(proxy, queue_no)) {
> > > > + virtio_error(vdev, "fail to set the vector %d",
> > > > new_vector);
>
> failed.
> and print errno?
>
> > > > + }
> > > > }
> > > > }
> > >
> > >
> > > Is this an unrelated fix?
> > >
> > this is for last version's comment, there is an return value for
> > function kvm_virtio_pci_vector_use_one, but
> > we can do nothing here, so I just add an erorr message
> > Thanks
> > cindy
>
>
> I'd make it a separate patch, documenting in the commit log what
> is going on.
>
sure, will do
thanks
cindy
> > > >
> > > > --
> > > > 2.45.0
> > >
>
