From e7ebf057e6a1ca4f5599caea143daa2135175a87 Mon Sep 17 00:00:00 2001 From: Elazar Leibovich Date: Sun, 15 Mar 2020 15:26:34 +0200 Subject: [PATCH] hw/scsi/vmw_pvscsi: Remove assertion for kick after reset 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 Signed-off-by: Liran Alon Message-Id: <20200315132634.113632-1-liran.alon@oracle.com> Signed-off-by: Paolo Bonzini --- hw/scsi/vmw_pvscsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c index c91352cf46..ec5bf9ea34 100644 --- a/hw/scsi/vmw_pvscsi.c +++ b/hw/scsi/vmw_pvscsi.c @@ -719,7 +719,10 @@ pvscsi_process_io(PVSCSIState *s) PVSCSIRingReqDesc descr; hwaddr next_descr_pa; - assert(s->rings_info_valid); + if (!s->rings_info_valid) { + return; + } + while ((next_descr_pa = pvscsi_ring_pop_req_descr(&s->rings)) != 0) { /* Only read after production index verification */