From: Elazar Leibovich <elazar.leibov...@oracle.com>
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.leibov...@oracle.com>
Signed-off-by: Liran Alon <liran.a...@oracle.com>
---
hw/scsi/vmw_pvscsi.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
index c91352cf46de..2491f204ddd7 100644
--- a/hw/scsi/vmw_pvscsi.c
+++ b/hw/scsi/vmw_pvscsi.c
@@ -29,6 +29,7 @@
#include "qapi/error.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
+#include "qemu/log.h"
#include "hw/scsi/scsi.h"
#include "migration/vmstate.h"
#include "scsi/constants.h"
@@ -719,7 +720,12 @@ pvscsi_process_io(PVSCSIState *s)
PVSCSIRingReqDesc descr;
hwaddr next_descr_pa;
- assert(s->rings_info_valid);
+ if (!s->rings_info_valid) {
+ qemu_log("WARNING: PVSCSI: Cannot process I/O when "
+ "rings are not valid.\n");
+ return;
+ }
+
while ((next_descr_pa = pvscsi_ring_pop_req_descr(&s->rings)) != 0) {
/* Only read after production index verification */
--
2.20.1
