Re: [Qemu-devel] [PATCH] seccomp: check TSYNC host capability

[Thomas Huth <thuth@redhat.com>]

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On 13/12/2018 04.24, David Gibson wrote:
> On Thu, Aug 30, 2018 at 04:33:48PM +0200, Marc-André Lureau wrote:
>> Remove -sandbox option if the host is not capable of TSYNC, since the
>> sandbox will fail at setup time otherwise. This will help libvirt, for
>> ex, to figure out if -sandbox will work.
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> This seems to have introduced a regression, which I found when
> preparing a ppc pull request.  Specifically when running with RHEL7 on
> a POWER host, using "-sandbox off" which one of my tests did, causes a
> cryptic error followed by a SEGV:
> 
> $ ./ppc64-softmmu/qemu-system-ppc64 -sandbox off
> qemu-system-ppc64: -sandbox off: There is no option group 'sandbox'
> Segmentation fault
> $ ./x86_64-softmmu/qemu-system-x86_64 -sandbox off
> qemu-system-x86_64: -sandbox off: There is no option group 'sandbox'
> Segmentation fault
> 
> I think the problem is that while this wrapped one use of the sandbox
> option group to produce a sensible error, it didn't do the same for
> another call to qemu_opts_parse_noisily():
> 
> (gdb) bt
> #0  0x00000000105b36d8 in opts_parse (list=0x0, params=0x3ffffffffab5 "off", permit_abbrev=true, defaults=false, errp=0x3ffffffff080)
>     at util/qemu-option.c:829
> #1  0x00000000105b3b74 in qemu_opts_parse_noisily (list=<optimized out>, params=<optimized out>, permit_abbrev=<optimized out>) at util/qemu-option.c:890
> #2  0x0000000010024964 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:3589
> 
> I'm guessing RHEL7 triggers it because that has a version of
> libseccomp that doesn't support the feature needed to complete
> registration (maybe on ppc host only; I haven't had a chance to try on
> an x86 RHEL7 host).

Andrea reported the same issue again today with QEMU v4.0 ...
Marc-André, have you ever had another look into this issue?

 Thomas



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