On 2013-09-03 14:18, Gleb Natapov wrote: > On Tue, Sep 03, 2013 at 12:06:33PM +0000, Zhanghaoyu (A) wrote: >> Hi, all >> >> Segmentation fault happened when reboot VM after hot-unplug virtio NIC, >> which can be reproduced 100%. >> See similar bug report to https://bugzilla.redhat.com/show_bug.cgi?id=988256 >> >> test environment: >> host: SLES11SP2 (kenrel version: 3.0.58) >> qemu: 1.5.1, upstream-qemu (commit 545825d4cda03ea292b7788b3401b99860efe8bc) >> libvirt: 1.1.0 >> guest os: win2k8 R2 x64bit or sles11sp2 x64 or win2k3 32bit >> >> You can reproduce this problem by following steps: >> 1. start a VM with virtio NIC(s) >> 2. hot-unplug a virtio NIC from the VM >> 3. reboot the VM, then segmentation fault happened during starting period >> >> the qemu backtrace shown as below: >> #0 0x00007ff4be3288d0 in __memcmp_sse4_1 () from /lib64/libc.so.6 >> #1 0x00007ff4c07f82c0 in patch_hypercalls (s=0x7ff4c15dd610) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/hw/i386/kvmvapic.c:549 >> #2 0x00007ff4c07f84f0 in vapic_prepare (s=0x7ff4c15dd610) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/hw/i386/kvmvapic.c:614 >> #3 0x00007ff4c07f85e7 in vapic_write (opaque=0x7ff4c15dd610, addr=0, >> data=32, size=2) >> at /mnt/zhanghaoyu/qemu/qemu-1.5.1/hw/i386/kvmvapic.c:651 >> #4 0x00007ff4c082a917 in memory_region_write_accessor >> (opaque=0x7ff4c15df938, addr=0, value=0x7ff4bbfe3d00, size=2, >> shift=0, mask=65535) at /mnt/zhanghaoyu/qemu/qemu-1.5.1/memory.c:334 >> #5 0x00007ff4c082a9ee in access_with_adjusted_size (addr=0, >> value=0x7ff4bbfe3d00, size=2, access_size_min=1, >> access_size_max=4, access=0x7ff4c082a89a <memory_region_write_accessor>, >> opaque=0x7ff4c15df938) >> at /mnt/zhanghaoyu/qemu/qemu-1.5.1/memory.c:364 >> #6 0x00007ff4c082ae49 in memory_region_iorange_write >> (iorange=0x7ff4c15dfca0, offset=0, width=2, data=32) >> at /mnt/zhanghaoyu/qemu/qemu-1.5.1/memory.c:439 >> #7 0x00007ff4c08236f7 in ioport_writew_thunk (opaque=0x7ff4c15dfca0, >> addr=126, data=32) >> at /mnt/zhanghaoyu/qemu/qemu-1.5.1/ioport.c:219 >> #8 0x00007ff4c0823078 in ioport_write (index=1, address=126, data=32) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/ioport.c:83 >> #9 0x00007ff4c0823ca9 in cpu_outw (addr=126, val=32) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/ioport.c:296 >> #10 0x00007ff4c0827485 in kvm_handle_io (port=126, data=0x7ff4c0510000, >> direction=1, size=2, count=1) >> at /mnt/zhanghaoyu/qemu/qemu-1.5.1/kvm-all.c:1485 >> #11 0x00007ff4c0827e14 in kvm_cpu_exec (env=0x7ff4c15bf270) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/kvm-all.c:1634 >> #12 0x00007ff4c07b6f27 in qemu_kvm_cpu_thread_fn (arg=0x7ff4c15bf270) at >> /mnt/zhanghaoyu/qemu/qemu-1.5.1/cpus.c:759 >> #13 0x00007ff4be58af05 in start_thread () from /lib64/libpthread.so.0 >> #14 0x00007ff4be2cd53d in clone () from /lib64/libc.so.6 >> >> If I apply below patch to the upstream qemu, this problem will disappear, >> --- >> hw/i386/kvmvapic.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c >> index 15beb80..6fff299 100644 >> --- a/hw/i386/kvmvapic.c >> +++ b/hw/i386/kvmvapic.c >> @@ -652,11 +652,11 @@ static void vapic_write(void *opaque, hwaddr addr, >> uint64_t data, >> switch (size) { >> case 2: >> if (s->state == VAPIC_INACTIVE) { >> - rom_paddr = (env->segs[R_CS].base + env->eip) & ROM_BLOCK_MASK; >> - s->rom_state_paddr = rom_paddr + data; >> - >> s->state = VAPIC_STANDBY; >> } >> + rom_paddr = (env->segs[R_CS].base + env->eip) & ROM_BLOCK_MASK; >> + s->rom_state_paddr = rom_paddr + data; >> + > Jan, does this mean that vapic state dies not move to inactive during > reset?
No, it I doesn't (derived from the original code). Maybe we can simply set it to inactive and clear rom_state_paddr. But this thing is nasty, need to re-check... Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux
