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 ---
> 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
> 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
> + 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);
> + }
> }
> }
Is this an unrelated fix?
>
> --
> 2.45.0
