> -----Original Message----- > From: Eduardo Habkost [mailto:ehabkost@xxxxxxxxxx] > Sent: Monday, June 4, 2018 9:46 PM > To: Moger, Babu <Babu.Moger@xxxxxxx> > Cc: mst@xxxxxxxxxx; marcel.apfelbaum@xxxxxxxxx; pbonzini@xxxxxxxxxx; > rth@xxxxxxxxxxx; mtosatti@xxxxxxxxxx; geoff@xxxxxxxxxxxxxxx; > kash@xxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > Subject: Re: [Qemu-devel] [PATCH v11 3/5] i386: Add support for > CPUID_8000_001E for AMD > > On Thu, May 24, 2018 at 11:43:32AM -0400, Babu Moger wrote: > > Add support for cpuid leaf CPUID_8000_001E. Build the config that closely > > match the underlying hardware. Please refer to the Processor > Programming > > Reference (PPR) for AMD Family 17h Model for more details. > > > > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > > --- > > target/i386/cpu.c | 61 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 61 insertions(+) > > > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > > index 0d423e5..9f8bad9 100644 > > --- a/target/i386/cpu.c > > +++ b/target/i386/cpu.c > > @@ -429,6 +429,62 @@ static void > encode_cache_cpuid8000001d(CPUCacheInfo *cache, CPUState *cs, > > (cache->complex_indexing ? CACHE_COMPLEX_IDX : 0); > > } > > > > +/* Data structure to hold the configuration info for a given core index */ > > +struct core_topology { > > + /* core complex id of the current core index */ > > + int ccx_id; > > + /* Adjusted core id for this core index in the topology */ > > What's an "adjusted core id"? When you build the topology, "adjusted core id" is the core index inside the core complex. There can be max 4 cores in a core complex, so this id can be 0, 1, 2, 3. I will change the name to ccx_core_index; > > > + int core_id; > > + /* Node id for this core index */ > > + int node_id; > > + /* Number of nodes in this config, 0 based */ > > + int num_nodes; > > I suggest making num_nodes carry the actual number of nodes, and > using (num_nodes - 1) when building CPUID data. Sure. Will do > > > +}; > > + > > +/* > > + * Build the configuration closely match the EPYC hardware. Using the > EPYC > > + * hardware configuration values (MAX_CCX, MAX_CORES_IN_CCX, > MAX_CORES_IN_NODE) > > + * right now. This could change in future. > > + * nr_cores : Total number of cores in the config > > + * core_id : Core index of the current CPU > > + * topo : Data structure to hold all the config info for this core index > > + */ > > +static void build_core_topology(int nr_cores, int core_id, > > + struct core_topology *topo) > > +{ > > + int nodes, cores_in_ccx; > > + > > + /* First get the number of nodes required */ > > + nodes = nodes_in_socket(nr_cores); > > + > > + cores_in_ccx = cores_in_core_complex(nr_cores); > > + > > + topo->node_id = core_id / (cores_in_ccx * MAX_CCX); > > + topo->ccx_id = (core_id % (cores_in_ccx * MAX_CCX)) / cores_in_ccx; > > + topo->core_id = core_id % cores_in_ccx; > > + /* num_nodes is 0 based, return n - 1 */ > > + topo->num_nodes = nodes - 1; > > +} > > Is this guaranteed to work with any nr_cores value, or only with > a few specific values that match real hardware? I have tested all the supported core values(1 to 32). All of them work fine. > > > > > + > > +/* Encode cache info for CPUID[8000001E] */ > > +static void encode_topo_cpuid8000001e(CPUState *cs, X86CPU *cpu, > > + uint32_t *eax, uint32_t *ebx, > > + uint32_t *ecx, uint32_t *edx) > > +{ > > + struct core_topology topo = {0}; > > + > > + build_core_topology(cs->nr_cores, cpu->core_id, &topo); > > + *eax = cpu->apic_id; > > + if (cs->nr_threads - 1) { > > + *ebx = ((cs->nr_threads - 1) << 8) | (topo.node_id << 3) | > > + (topo.ccx_id << 2) | topo.core_id; > > + } else { > > + *ebx = (topo.node_id << 4) | (topo.ccx_id << 3) | topo.core_id; > > + } > > This part confuses me a lot. Where are those bit offsets in EBX > defined? Bit 7-0 is core id. This decodes to where in the topology the core is located. (2 bits for node, 2 bits for core complex and 3 bit index). I will add those details in the comments. > > Is this guaranteed to work with any cs->nr_cores value? > > > > + *ecx = (topo.num_nodes << 8) | (cpu->socket_id << 2) | topo.node_id; > > Like on EBX, I'm confused by the bit offsets. Where are they > defined? > Bit 7-0 is Node id. This decodes to 1 bit for socket and 2 bits for node_id. I will add those details in comments. > Probably it's safer to not allow TOPOEXT to be enabled if the CPU > socket/core/thread topology configuration can't generate a sane > node/core-complex topology. Like I said before It may become too restrictive. I have tested all the numbers (1 to 32). They all appear to work ok. > > > > + *edx = 0; > > +} > > + > > /* > > * Definitions of the hardcoded cache entries we expose: > > * These are legacy cache values. If there is a need to change any > > @@ -4122,6 +4178,11 @@ void cpu_x86_cpuid(CPUX86State *env, > uint32_t index, uint32_t count, > > break; > > } > > break; > > + case 0x8000001E: > > + assert(cpu->core_id <= 255); > > + encode_topo_cpuid8000001e(cs, cpu, > > + eax, ebx, ecx, edx); > > + break; > > case 0xC0000000: > > *eax = env->cpuid_xlevel2; > > *ebx = 0; > > -- > > 1.8.3.1 > > > > > > -- > Eduardo
