On Mon, 22 Jul 2024 at 15:24, Jason Wang <jasow...@redhat.com> wrote: > > Hi Cindy > > On Fri, Jul 19, 2024 at 1:25 PM Cindy Lu <l...@redhat.com> 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 > > > > In this bug, they are using the virtio_input device. The guest notifier was > > not supported for this device, The function virtio_pci_set_guest_notifiers() > > was not called, and the vector_irqfd was not initialized. > > > > So the fix is adding the check for vector_irqfd in virtio_pci_get_notifier() > > > > But The function virtio_pci_get_notifier(),it can also be used in all kinds of device. > > If the vector_irqfd still didn't initial after the VIRTIO_CONFIG_S_DRIVER_OK is set > > means this device is not using guest notifier. We can let the check fail 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 > > Signed-off-by: Cindy Lu <l...@redhat.com> > > --- > > hw/virtio/virtio-pci.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > index 592fdaa10f..dc31a37ec0 100644 > > --- a/hw/virtio/virtio-pci.c > > +++ b/hw/virtio/virtio-pci.c > > @@ -860,6 +860,9 @@ 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 && vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) > > + return -1; > > + > > Did this mean !proxy->vector_irqfd && !(vdev->status & > VIRTIO_CONFIG_S_DRIVER_OK)) is legal? > > Thanks > yes, for my test, I didn't meet this kind of environment. However, since this function is used widely in many environments, I cannot cover all devices for testing.
I think we can change the patch back to the first version, which is to check the proxy->vector_irqfd in virtio_pci_set_vector(). This will have a lower risk and make more sense thanks cindy On Mon, 22 Jul 2024 at 15:24, Jason Wang <jasow...@redhat.com> wrote: > Hi Cindy > > On Fri, Jul 19, 2024 at 1:25 PM Cindy Lu <l...@redhat.com> 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 > > > > In this bug, they are using the virtio_input device. The guest notifier > was > > not supported for this device, The function > virtio_pci_set_guest_notifiers() > > was not called, and the vector_irqfd was not initialized. > > > > So the fix is adding the check for vector_irqfd in > virtio_pci_get_notifier() > > > > But The function virtio_pci_get_notifier(),it can also be used in all > kinds of device. > > If the vector_irqfd still didn't initial after the > VIRTIO_CONFIG_S_DRIVER_OK is set > > means this device is not using guest notifier. We can let the check fail > 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 > > Signed-off-by: Cindy Lu <l...@redhat.com> > > --- > > hw/virtio/virtio-pci.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > index 592fdaa10f..dc31a37ec0 100644 > > --- a/hw/virtio/virtio-pci.c > > +++ b/hw/virtio/virtio-pci.c > > @@ -860,6 +860,9 @@ 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 && vdev->status & > VIRTIO_CONFIG_S_DRIVER_OK) > > + return -1; > > + > > Did this mean !proxy->vector_irqfd && !(vdev->status & > VIRTIO_CONFIG_S_DRIVER_OK)) is legal? > > Thanks > > > if (queue_no == VIRTIO_CONFIG_IRQ_IDX) { > > *n = virtio_config_get_guest_notifier(vdev); > > *vector = vdev->config_vector; > > -- > > 2.45.0 > > > >
