Hi Cindy,
On 17/6/24 11:55, 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 to add the check for vector_irqfd.
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 | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index b1d02f4b3d..502aad28b2 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1442,7 +1442,9 @@ static void virtio_pci_set_vector(VirtIODevice *vdev,
* Otherwise just need to set the new vector on the device.
*/
if (kvm_irqfd && old_vector != VIRTIO_NO_VECTOR) {
- kvm_virtio_pci_vector_release_one(proxy, queue_no);
+ if (proxy->vector_irqfd) {
Shouldn't this go into called virtio_pci_get_notifier()?
+ kvm_virtio_pci_vector_release_one(proxy, queue_no);
We ignore this function return value, is it safe/expected?
+ }
}
