[v1] hw/scsi/vmw_pvscsi: Remove assertion for kick after reset

[PATCH] hw/scsi/vmw_pvscsi: Remove assertion for kick after reset

Posted by Liran Alon 5 years, 11 months ago

From: Elazar Leibovich <elazar.leibovich@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.leibovich@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
---
 hw/scsi/vmw_pvscsi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
index c91352cf46de..b2bb80449bba 100644
--- a/hw/scsi/vmw_pvscsi.c
+++ b/hw/scsi/vmw_pvscsi.c
@@ -719,7 +719,12 @@ 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

Re: [PATCH] hw/scsi/vmw_pvscsi: Remove assertion for kick after reset

Posted by no-reply@patchew.org 5 years, 11 months ago

Patchew URL: https://patchew.org/QEMU/20200315132634.113632-1-liran.alon@oracle.com/



Hi,

This series failed the docker-mingw@fedora build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#! /bin/bash
export ARCH=x86_64
make docker-image-fedora V=1 NETWORK=1
time make docker-test-mingw@fedora J=14 NETWORK=1
=== TEST SCRIPT END ===

  CC      replay/replay.o
  CC      replay/replay-internal.o
/tmp/qemu-test/src/hw/scsi/vmw_pvscsi.c: In function 'pvscsi_process_io':
/tmp/qemu-test/src/hw/scsi/vmw_pvscsi.c:723:9: error: implicit declaration of function 'qemu_log'; did you mean 'qemu_fork'? [-Werror=implicit-function-declaration]
         qemu_log("WARNING: PVSCSI: Cannot process I/O when "
         ^~~~~~~~
         qemu_fork
/tmp/qemu-test/src/hw/scsi/vmw_pvscsi.c:723:9: error: nested extern declaration of 'qemu_log' [-Werror=nested-externs]
cc1: all warnings being treated as errors
make: *** [/tmp/qemu-test/src/rules.mak:69: hw/scsi/vmw_pvscsi.o] Error 1
make: *** Waiting for unfinished jobs....
Traceback (most recent call last):
  File "./tests/docker/docker.py", line 664, in <module>
---
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--label', 'com.qemu.instance.uuid=b60fe0dffe2b447eb06a7f9f46d9f5aa', '-u', '1001', '--security-opt', 'seccomp=unconfined', '--rm', '-e', 'TARGET_LIST=', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-sakg1pkp/src/docker-src.2020-03-15-10.25.38.6677:/var/tmp/qemu:z,ro', 'qemu:fedora', '/var/tmp/qemu/run', 'test-mingw']' returned non-zero exit status 2.
filter=--filter=label=com.qemu.instance.uuid=b60fe0dffe2b447eb06a7f9f46d9f5aa
make[1]: *** [docker-run] Error 1
make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-sakg1pkp/src'
make: *** [docker-run-test-mingw@fedora] Error 2

real    2m8.180s
user    0m8.937s


The full log is available at
http://patchew.org/logs/20200315132634.113632-1-liran.alon@oracle.com/testing.docker-mingw@fedora/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [PATCH] hw/scsi/vmw_pvscsi: Remove assertion for kick after reset

Posted by Paolo Bonzini 5 years, 10 months ago

On 15/03/20 14:26, Liran Alon wrote:
> From: Elazar Leibovich <elazar.leibovich@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.leibovich@oracle.com>
> Signed-off-by: Liran Alon <liran.alon@oracle.com>
> ---
>  hw/scsi/vmw_pvscsi.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
> index c91352cf46de..b2bb80449bba 100644
> --- a/hw/scsi/vmw_pvscsi.c
> +++ b/hw/scsi/vmw_pvscsi.c
> @@ -719,7 +719,12 @@ 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 */
> 

Queued, with the qemu_log removed even.

Paolo