| Message ID | 20240627-add-cpu-type-v2-1-f927bde83ad0@linux.intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add CPU-type to topology | expand |
On Thu, Jun 27, 2024 at 01:44:06PM -0700, Pawan Gupta wrote: > The hw_cpu_type is populated in the below debugfs file: > > # cat /sys/kernel/debug/x86/topo/cpus/# What "below debugfs file"? A '#'? > diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c > index 3baf3e435834..8082e03a5976 100644 > --- a/arch/x86/kernel/cpu/debugfs.c > +++ b/arch/x86/kernel/cpu/debugfs.c > @@ -22,6 +22,7 @@ static int cpu_debug_show(struct seq_file *m, void *p) > seq_printf(m, "die_id: %u\n", c->topo.die_id); > seq_printf(m, "cu_id: %u\n", c->topo.cu_id); > seq_printf(m, "core_id: %u\n", c->topo.core_id); > + seq_printf(m, "hw_cpu_type: %x\n", c->topo.hw_cpu_type); Yeah, no, we're not going to perpetuate this silliness of printing hex values without a preceding "0x". > seq_printf(m, "logical_pkg_id: %u\n", c->topo.logical_pkg_id); > seq_printf(m, "logical_die_id: %u\n", c->topo.logical_die_id); > seq_printf(m, "llc_id: %u\n", c->topo.llc_id); > diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c > index 9a6069e7133c..8b47bd6b0623 100644 > --- a/arch/x86/kernel/cpu/topology_common.c > +++ b/arch/x86/kernel/cpu/topology_common.c > @@ -140,6 +140,14 @@ static void parse_topology(struct topo_scan *tscan, bool early) > } > } > > +static void topo_set_hw_cpu_type(struct cpuinfo_x86 *c) > +{ > + c->topo.hw_cpu_type = X86_HW_CPU_TYPE_UNKNOWN; > + > + if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >= 0x1a) > + c->topo.hw_cpu_type = cpuid_eax(0x1a) >> X86_CPU_TYPE_INTEL_SHIFT; > +} Why isn't this happening in cpu/intel.c? And then you don't need yet another silly function.
On Fri, Jun 28, 2024 at 10:03:05AM +0200, Borislav Petkov wrote: > On Thu, Jun 27, 2024 at 01:44:06PM -0700, Pawan Gupta wrote: > > The hw_cpu_type is populated in the below debugfs file: > > > > # cat /sys/kernel/debug/x86/topo/cpus/# > > What "below debugfs file"? A '#'? That is the number of the CPU. If it is causing confusion, I can will change it to N, or say # means the number of the CPU. > > diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c > > index 3baf3e435834..8082e03a5976 100644 > > --- a/arch/x86/kernel/cpu/debugfs.c > > +++ b/arch/x86/kernel/cpu/debugfs.c > > @@ -22,6 +22,7 @@ static int cpu_debug_show(struct seq_file *m, void *p) > > seq_printf(m, "die_id: %u\n", c->topo.die_id); > > seq_printf(m, "cu_id: %u\n", c->topo.cu_id); > > seq_printf(m, "core_id: %u\n", c->topo.core_id); > > + seq_printf(m, "hw_cpu_type: %x\n", c->topo.hw_cpu_type); > > Yeah, no, we're not going to perpetuate this silliness of printing hex > values without a preceding "0x". I thought about that, but the other fields are also printed without a preceding "0x": seq_printf(m, "initial_apicid: %x\n", c->topo.initial_apicid); seq_printf(m, "apicid: %x\n", c->topo.apicid); ... I will change those too, probably in a separate patch. > > +static void topo_set_hw_cpu_type(struct cpuinfo_x86 *c) > > +{ > > + c->topo.hw_cpu_type = X86_HW_CPU_TYPE_UNKNOWN; > > + > > + if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >= 0x1a) > > + c->topo.hw_cpu_type = cpuid_eax(0x1a) >> X86_CPU_TYPE_INTEL_SHIFT; > > +} > > Why isn't this happening in cpu/intel.c? And then you don't need yet > another silly function. I was preferring to keep the topology related code in one place. Would it make sense to keep it in Intel specific leg in parse_topology() as below: --- diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index 8b47bd6b0623..c8869e75365f 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -87,6 +87,7 @@ static void parse_topology(struct topo_scan *tscan, bool early) .cu_id = 0xff, .llc_id = BAD_APICID, .l2c_id = BAD_APICID, + .hw_cpu_type = X86_HW_CPU_TYPE_UNKNOWN, }; struct cpuinfo_x86 *c = tscan->c; struct { @@ -132,6 +133,8 @@ static void parse_topology(struct topo_scan *tscan, bool early) case X86_VENDOR_INTEL: if (!IS_ENABLED(CONFIG_CPU_SUP_INTEL) || !cpu_parse_topology_ext(tscan)) parse_legacy(tscan); + if (c->cpuid_level >= 0x1a) + c->topo.hw_cpu_type = cpuid_eax(0x1a) >> X86_CPU_TYPE_INTEL_SHIFT; break; case X86_VENDOR_HYGON: if (IS_ENABLED(CONFIG_CPU_SUP_HYGON))
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index cb4f6c513c48..d8d715fcc25c 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -105,6 +105,9 @@ struct cpuinfo_topology { // Cache level topology IDs u32 llc_id; u32 l2c_id; + + // Hardware defined CPU-type + u8 hw_cpu_type; }; struct cpuinfo_x86 { diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index abe3a8f22cbd..717fdb928dc3 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -33,6 +33,14 @@ #include <linux/numa.h> #include <linux/cpumask.h> +#define X86_CPU_TYPE_INTEL_SHIFT 24 + +enum x86_hw_topo_cpu_type { + X86_HW_CPU_TYPE_UNKNOWN = 0, + X86_HW_CPU_TYPE_INTEL_ATOM = 0x20, + X86_HW_CPU_TYPE_INTEL_CORE = 0x40, +}; + #ifdef CONFIG_NUMA #include <asm/mpspec.h> @@ -139,6 +147,7 @@ extern const struct cpumask *cpu_clustergroup_mask(int cpu); #define topology_logical_die_id(cpu) (cpu_data(cpu).topo.logical_die_id) #define topology_die_id(cpu) (cpu_data(cpu).topo.die_id) #define topology_core_id(cpu) (cpu_data(cpu).topo.core_id) +#define topology_hw_cpu_type(cpu) (cpu_data(cpu).topo.hw_cpu_type) #define topology_ppin(cpu) (cpu_data(cpu).ppin) #define topology_amd_node_id(cpu) (cpu_data(cpu).topo.amd_node_id) diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c index 3baf3e435834..8082e03a5976 100644 --- a/arch/x86/kernel/cpu/debugfs.c +++ b/arch/x86/kernel/cpu/debugfs.c @@ -22,6 +22,7 @@ static int cpu_debug_show(struct seq_file *m, void *p) seq_printf(m, "die_id: %u\n", c->topo.die_id); seq_printf(m, "cu_id: %u\n", c->topo.cu_id); seq_printf(m, "core_id: %u\n", c->topo.core_id); + seq_printf(m, "hw_cpu_type: %x\n", c->topo.hw_cpu_type); seq_printf(m, "logical_pkg_id: %u\n", c->topo.logical_pkg_id); seq_printf(m, "logical_die_id: %u\n", c->topo.logical_die_id); seq_printf(m, "llc_id: %u\n", c->topo.llc_id); diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index 9a6069e7133c..8b47bd6b0623 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -140,6 +140,14 @@ static void parse_topology(struct topo_scan *tscan, bool early) } } +static void topo_set_hw_cpu_type(struct cpuinfo_x86 *c) +{ + c->topo.hw_cpu_type = X86_HW_CPU_TYPE_UNKNOWN; + + if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >= 0x1a) + c->topo.hw_cpu_type = cpuid_eax(0x1a) >> X86_CPU_TYPE_INTEL_SHIFT; +} + static void topo_set_ids(struct topo_scan *tscan, bool early) { struct cpuinfo_x86 *c = tscan->c; @@ -190,6 +198,7 @@ void cpu_parse_topology(struct cpuinfo_x86 *c) } topo_set_ids(&tscan, false); + topo_set_hw_cpu_type(c); } void __init cpu_init_topology(struct cpuinfo_x86 *c)
Sometimes it is required to identify the type of a core for taking specific actions e.g. intel_pstate driver uses the core type to determine CPU scaling. Also, some CPU vulnerabilities only affect a specific CPU type e.g. RFDS only affects Intel Atom. For hybrid systems that have variants P+E, P-only(Core) and E-only(Atom), it gets challenging to identify which variant is vulnerable to a specific vulnerability, as these variants share the same family, model and stepping. Such processors do have CPUID fields that uniquely identify them. Like, P+E, P-only and E-only enumerates CPUID.1A.CORE_TYPE, while P+E additionally enumerates CPUID.7.HYBRID. Linux does not currently use this field. Add a new field hw_cpu_type to struct cpuinfo_topology which can be used to match a CPU based on its type. The hw_cpu_type is populated in the below debugfs file: # cat /sys/kernel/debug/x86/topo/cpus/# Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> --- arch/x86/include/asm/processor.h | 3 +++ arch/x86/include/asm/topology.h | 9 +++++++++ arch/x86/kernel/cpu/debugfs.c | 1 + arch/x86/kernel/cpu/topology_common.c | 9 +++++++++ 4 files changed, 22 insertions(+)