When running Ubuntu 3.13.0-65-generic guest, QEMU sometimes crashes
during guest ACPI reset. It crashes on assert(s->rings_info_valid)
in pvscsi_process_io().
Analyzing the crash revealed that it happens when userspace issues
a sync during a reboot syscall.
Below are backtraces we gathered from the guests.
Guest backtrace when issuing PVSCSI_CMD_ADAPTER_RESET:
pci_device_shutdown
device_shutdown
init_pid_ns
init_pid_ns
kernel_power_off
SYSC_reboot
Guest backtrace when issuing PVSCSI_REG_OFFSET_KICK_RW_IO:
scsi_done
scsi_dispatch_cmd
blk_add_timer
scsi_request_fn
elv_rb_add
__blk_run_queue
queue_unplugged
blk_flush_plug_list
blk_finish_plug
ext4_writepages
set_next_entity
do_writepages
__filemap_fdatawrite_range
filemap_write_and_wait_range
ext4_sync_file
ext4_sync_file
do_fsync
sys_fsync
Since QEMU pvscsi should imitate VMware pvscsi device emulation,
we decided to imitate VMware's behavior in this case.
To check VMware behavior, we wrote a kernel module that issues
a reset to the pvscsi device and then issues a kick. We ran it on
VMware ESXi 6.5 and it seems that it simply ignores the kick.
Hence, we decided to ignore the kick as well.
Signed-off-by: Elazar Leibovich <elazar.leibovich@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Message-Id: <20200315132634.113632-1-liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
e7ebf057e6