> -----Original Message----- > From: Eduardo Habkost [mailto:ehabkost@xxxxxxxxxx] > Sent: Wednesday, June 6, 2018 5:06 PM > To: Moger, Babu <Babu.Moger@xxxxxxx> > Cc: mst@xxxxxxxxxx; marcel.apfelbaum@xxxxxxxxx; pbonzini@xxxxxxxxxx; > rth@xxxxxxxxxxx; mtosatti@xxxxxxxxxx; qemu-devel@xxxxxxxxxx; > kvm@xxxxxxxxxxxxxxx; kash@xxxxxxxxxxxxxx; geoff@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v12 2/4] i386: Verify if topoext feature can be supported > > On Wed, Jun 06, 2018 at 10:36:44AM -0400, Babu Moger wrote: > > topoext feature cannot be supported in certain cases > > with large number of cores or threads. Add the check. > > > > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > > --- > > target/i386/cpu.c | 27 +++++++++++++++++++++++++++ > > 1 file changed, 27 insertions(+) > > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > index 86fb1a4..fc5c66d 100644 > > --- a/target/i386/cpu.c > > +++ b/target/i386/cpu.c > > @@ -509,6 +509,20 @@ static void encode_topo_cpuid8000001e(CPUState > *cs, X86CPU *cpu, > > } > > > > /* > > + * Check if we can support this topology > > + * Fail if number of cores are beyond the supported config > > + * or nr_threads is more than 2 > > + */ > > +static int topology_supports_topoext(int nr_cores, int nr_threads) > > +{ > > + if ((nr_cores > (MAX_CORES_IN_NODE * MAX_NODES_PER_SOCKET)) > || > > + (nr_threads > 2)) { > > + return 0; > > + } > > + return 1; > > +} > > + > > +/* > > * Definitions of the hardcoded cache entries we expose: > > * These are legacy cache values. If there is a need to change any > > * of these values please use builtin_x86_defs > > @@ -4941,6 +4955,19 @@ static void x86_cpu_realizefn(DeviceState *dev, > Error **errp) > > > > qemu_init_vcpu(cs); > > > > + /* On AMD systems, check if we can support topoext feature */ > > + if (IS_AMD_CPU(env) && > > + (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT)) { > > + if (!topology_supports_topoext(cs->nr_cores, cs->nr_threads)) { > > + /* Cannot support topoext */ > > + error_setg(errp, "CPU model does not support topoext feature " > > + "with number of cores(%d) and threads(%d). " > > + "Please configure -smp options properly.", > > + cs->nr_cores, cs->nr_threads); > > See error.h documentation: > > * Error reporting system loosely patterned after Glib's GError. > * > * Create an error: > * error_setg(&err, "situation normal, all fouled up"); > * > * Create an error and add additional explanation: > * error_setg(&err, "invalid quark"); > * error_append_hint(&err, "Valid quarks are up, down, strange, " > * "charm, top, bottom.\n"); > * > * Do *not* contract this to > * error_setg(&err, "invalid quark\n" > * "Valid quarks are up, down, strange, charm, top, bottom."); > * > > I suggest something like this: Sure. I will make these changes. Thanks > > static bool topology_supports_topoext(int nr_cores, int nr_threads, Error > **errp) > { > if (nr_cores > (MAX_CORES_IN_NODE * MAX_NODES_PER_SOCKET))) { > error_setg(errp, "TOPOEXT unsupported with %d cores per socket", > nr_cores); > error_append_hint(errp, "TOPOEXT supports only up to %d cores per > socket", > (MAX_CORES_IN_NODE * MAX_NODES_PER_SOCKET)); > return false; > } > if (nr_threads > 2) { > error_setg(errp, "TOPOEXT unsupported with %d threads per core", > nr_threads); > error_append_hint(errp, "TOPOEXT supports only up to 2 threads per > core"); > (MAX_CORES_IN_NODE * MAX_NODES_PER_SOCKET)); > return false; > } > return true; > } > > static void x86_cpu_realizefn(DeviceState *dev, Error **errp) > { > /* ... */ > if (IS_AMD_CPU(env) && > (env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) && > !topology_supports_topoext(cs->nr_cores, cs->nr_threads, errp)) { > return; > } > /* ... */ > } > > -- > Eduardo
