At some point, after unplugging virtio-pci the virtio device may be unrealised, but the memory regions may be present in flatview. So, it's a possible situation when memory region's callbacks are called for "unplugged" device.
In patches were added checks for virtio device presence on virtio-bus. Added checks in PCI config callbacks. Also changed return values in memory regions read if virtio not present. BZ link https://bugzilla.redhat.com/show_bug.cgi?id=1938042 The issue similar to https://bugzilla.redhat.com/show_bug.cgi?id=1743098 Backtrace: at ../hw/virtio/virtio-pci.c:1271 proxy = 0x560b535f8bf0 vdev = 0x0 (mr=<optimized out>, addr=<optimized out>, value=<optimized out>, size=<optimized out>, shift=<optimized out>, mask=<optimized out>, attrs=...) at ../softmmu/memory.c:491 tmp = <optimized out> (addr=addr@entry=22, value=value@entry=0x7fd743dfe518, size=size@entry=2, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=0x560b513fc500 <memory_region_write_accessor>, mr=0x560b535f95d0, attrs=...) at ../softmmu/memory.c:552 access_mask = 65535 access_size = 2 i = <optimized out> r = 0 (mr=mr@entry=0x560b535f95d0, addr=22, data=<optimized out>, op=<optimized out>, attrs=attrs@entry=...) at ../softmmu/memory.c:1501 size = 2 (fv=fv@entry=0x7fd6f005d3b0, addr=addr@entry=4246716438, attrs=..., ptr=ptr@entry=0x7fe69b2b0028, len=len@entry=2, addr1=<optimized out>, l=<optimized out>, mr=0x560b535f95d0) at /usr/src/debug/qemu-kvm-5.2.0-11.module+el8.4.0+10268+62bcbbed.x86_64/include/qemu/host-utils.h:164 ram_ptr = <optimized out> val = <optimized out> result = 0 release_lock = true buf = 0x7fe69b2b0028 "" at ../softmmu/physmem.c:2799 l = 2 addr1 = 22 mr = <optimized out> result = 0 _rcu_read_auto = 0x1 result = 0 fv = <optimized out> attrs = {unspecified = 0, secure = 0, user = 0, requester_id = 0, byte_swap = 0, target_tlb_bit0 = 0, target_tlb_bit1 = 0, target_tlb_bit2 = 0} run = <optimized out> ret = <optimized out> run_ret = 0 cpu = 0x560b522738d0 r = <optimized out> __clframe = {__cancel_routine = <optimized out>, __cancel_arg = 0x0, __do_it = 1, __cancel_type = <optimized out>} qemu_thread_args = 0x560b5229a6f0 start_routine = 0x560b513faeb0 <kvm_vcpu_thread_fn> arg = 0x560b522738d0 r = <optimized out> Andrew Melnychenko (3): virtio-pci: Added check for virtio device presence in mm callbacks. virtio-pci: Added check for virtio device in PCI config cbs. virtio-pci: Changed return values for "notify", "device" and "isr" read. hw/virtio/virtio-pci.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) -- 2.31.1
