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

[David Gibson]

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 <address@hidden>

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).

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

signature.asc
Description: PGP signature