Re: [Qemu-devel] [PATCH for-3.1] tests/cpu-plug-test: check CPU hotplug on ppc64 with KVM

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Jul 25, 2018 at 04:45:26PM +0200, Greg Kurz wrote:
> Commit b585395b655 fixed a regression introduced by some recent changes
> in the XICS code, that was causing QEMU to crash instantly during CPU
> hotplug with KVM. This is typically the kind of bug we'd like our
> test suite to detect before it gets merged. Unfortunately, the current
> tests run with '-machine accel=qtest' and don't exercise KVM specific
> paths in QEMU.
> 
> This patch hence changes add_pseries_test_case() to launch QEMU with
> '-machine accel=kvm' if KVM is available.
> 
> A notable consequence is that the guest will execute SLOF, but for some
> reasons SLOF sometimes hits a program exception. This causes the guest
> to loop forever and the test to be stuck.  Since we don't need the guest
> to be truely running, let's pass -S to QEMU to avoid that.
> 
> Also disable machine capabilities that could be unavailable in KVM, eg,
> when using PR KVM.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>

I'm pretty sure trying to change the accelerator on a qtest test just
doesn't make sense.  We'd need a different approach for testing cpu
hotplug against kvm & tcg backends.

> ---
>  tests/cpu-plug-test.c |   20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/cpu-plug-test.c b/tests/cpu-plug-test.c
> index 5f39ba0df394..2107557809b7 100644
> --- a/tests/cpu-plug-test.c
> +++ b/tests/cpu-plug-test.c
> @@ -21,6 +21,7 @@ struct PlugTestData {
>      unsigned cores;
>      unsigned threads;
>      unsigned maxcpus;
> +    const char *extra_args;
>  };
>  typedef struct PlugTestData PlugTestData;
>  
> @@ -106,9 +107,10 @@ static void test_plug_with_device_add_coreid(gconstpointer data)
>      char *args;
>      unsigned int c;
>  
> -    args = g_strdup_printf("-machine %s -cpu %s "
> +    args = g_strdup_printf("-machine %s -cpu %s %s "
>                             "-smp 1,sockets=%u,cores=%u,threads=%u,maxcpus=%u",
>                             td->machine, td->cpu_model,
> +                           td->extra_args ? td->extra_args : "",
>                             td->sockets, td->cores, td->threads, td->maxcpus);
>      qtest_start(args);
>  
> @@ -195,10 +197,20 @@ static void add_pseries_test_case(const char *mname)
>          (g_str_has_prefix(mname, "pseries-2.") && atoi(&mname[10]) < 7)) {
>          return;
>      }
> -    data = g_new(PlugTestData, 1);
> +    data = g_new0(PlugTestData, 1);
>      data->machine = g_strdup(mname);
>      data->cpu_model = "power8_v2.0";
> -    data->device_model = g_strdup("power8_v2.0-spapr-cpu-core");
> +    if (!access("/sys/module/kvm_hv", F_OK) ||
> +        !access("/sys/module/kvm_pr", F_OK)) {
> +        data->cpu_model = "host";
> +        data->extra_args =
> +            "-machine accel=kvm "
> +            "-machine cap-cfpc=broken,cap-sbbc=broken,cap-ibs=broken "
> +            "-machine cap-htm=off "
> +            "-machine cap-hpt-max-page-size=64k "
> +            "-S";
> +    }
> +    data->device_model = g_strdup_printf("%s-spapr-cpu-core", data->cpu_model);
>      data->sockets = 2;
>      data->cores = 3;
>      data->threads = 1;
> @@ -221,7 +233,7 @@ static void add_s390x_test_case(const char *mname)
>          return;
>      }
>  
> -    data = g_new(PlugTestData, 1);
> +    data = g_new0(PlugTestData, 1);
>      data->machine = g_strdup(mname);
>      data->cpu_model = "qemu";
>      data->device_model = g_strdup("qemu-s390x-cpu");
> 

-- 
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

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