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

[Greg Kurz]

On Wed, 16 Nov 2016 09:39:31 +0100
Thomas Huth <address@hidden> 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.

> Signed-off-by: Thomas Huth <address@hidden>
> ---
>  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();
>      }