Re: [Qemu-devel] [PATCH] tests/postcopy: Use KVM on ppc64 only if it is KVM-HV

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Greg Kurz (groug@kaod.org) wrote:
> On Wed, 16 Nov 2016 09:39:31 +0100
> Thomas Huth <thuth@redhat.com> wrote:
> 
> > The ppc64 postcopy test does not work with KVM-PR, and it is also
> > causing annoying warning messages when run on a x86 host. So let's
> > use KVM here only if we know that we're running with KVM-HV (which
> > automatically also means that we're running on a ppc64 host), and
> > fall back to TCG otherwise.
> > 
> 
> This patch addresses two issues actually:
> - the annoying warning when running on a ppc64 guest on a non-ppc64 host
> - the fact that KVM-PR seems to be currently broken
> 
> I agree that the former makes sense, but what about the case of running
> a x86 guest on a non-x86 host ?
> 
> I'm still feeling uncomfortable with the KVM-PR case... is this a workaround
> we want to keep until we find out what's going on or are we starting to
> partially deprecate KVM PR ? In any case, I guess we should document this
> and probably print some meaningful error message.

This is certainly a work around for now, it doesn't suggest anything about
deprecation.

Dave

> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  tests/postcopy-test.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/tests/postcopy-test.c b/tests/postcopy-test.c
> > index d6613c5..dafe8be 100644
> > --- a/tests/postcopy-test.c
> > +++ b/tests/postcopy-test.c
> > @@ -380,17 +380,21 @@ static void test_migrate(void)
> >                                    " -incoming %s",
> >                                    tmpfs, bootpath, uri);
> >      } else if (strcmp(arch, "ppc64") == 0) {
> > +        const char *accel;
> > +
> > +        /* On ppc64, the test only works with kvm-hv, but not with kvm-pr */
> > +        accel = access("/sys/module/kvm_hv", F_OK) ? "tcg" : "kvm:tcg";
> >          init_bootfile_ppc(bootpath);
> > -        cmd_src = g_strdup_printf("-machine accel=kvm:tcg -m 256M"
> > +        cmd_src = g_strdup_printf("-machine accel=%s -m 256M"
> >                                    " -name pcsource,debug-threads=on"
> >                                    " -serial file:%s/src_serial"
> >                                    " -drive file=%s,if=pflash,format=raw",
> > -                                  tmpfs, bootpath);
> > -        cmd_dst = g_strdup_printf("-machine accel=kvm:tcg -m 256M"
> > +                                  accel, tmpfs, bootpath);
> > +        cmd_dst = g_strdup_printf("-machine accel=%s -m 256M"
> >                                    " -name pcdest,debug-threads=on"
> >                                    " -serial file:%s/dest_serial"
> >                                    " -incoming %s",
> > -                                  tmpfs, uri);
> > +                                  accel, tmpfs, uri);
> >      } else {
> >          g_assert_not_reached();
> >      }
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK