From: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Sometimes it is required to take actions based on if a CPU is a performance
or efficiency core. As an example, intel_pstate driver uses the Intel
core-type to determine CPU scaling. Also, some CPU vulnerabilities only
affect a specific CPU type, like RFDS only affects Intel Atom. Hybrid
systems that have variants P+E, P-only(Core) and E-only(Atom), it is not
straightforward to identify which variant is affected by a type specific
vulnerability.
Such processors do have CPUID field that can uniquely identify them. Like,
P+E, P-only and E-only enumerates CPUID.1A.CORE_TYPE identification, while
P+E additionally enumerates CPUID.7.HYBRID. Based on this information, it
is possible for boot CPU to identify if a system has mixed CPU types.
Add a new field hw_cpu_type to struct cpuinfo_topology that stores the
hardware specific CPU type. This saves the overhead of IPIs to get the CPU
type of a different CPU. CPU type is populated early in the boot process,
before vulnerabilities are enumerated.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Co-developed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
v2->v3:
* Remove a bunch of boilerplate code
* Convert to showing string in debugfs
* Rename to get_topology_generic_cpu_type/get_topology_cpu_type_name
* Add Intel definitions to intel-family.h
---
arch/x86/include/asm/intel-family.h | 6 +++++
arch/x86/include/asm/processor.h | 18 ++++++++++++++
arch/x86/include/asm/topology.h | 9 +++++++
arch/x86/kernel/cpu/debugfs.c | 1 +
arch/x86/kernel/cpu/topology_amd.c | 3 +++
arch/x86/kernel/cpu/topology_common.c | 34 +++++++++++++++++++++++++++
6 files changed, 71 insertions(+)
diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 1a42f829667a3..7367644720484 100644
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -183,4 +183,10 @@
/* Family 19 */
#define INTEL_PANTHERCOVE_X IFM(19, 0x01) /* Diamond Rapids */
+/* CPU core types */
+enum intel_cpu_type {
+ INTEL_CPU_TYPE_ATOM = 0x20,
+ INTEL_CPU_TYPE_CORE = 0x40,
+};
+
#endif /* _ASM_X86_INTEL_FAMILY_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4a686f0e5dbf6..c0975815980c8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -105,6 +105,24 @@ struct cpuinfo_topology {
// Cache level topology IDs
u32 llc_id;
u32 l2c_id;
+
+ // Hardware defined CPU-type
+ union {
+ u32 cpu_type;
+ struct {
+ // CPUID.1A.EAX[23-0]
+ u32 intel_native_model_id :24;
+ // CPUID.1A.EAX[31-24]
+ u32 intel_type :8;
+ };
+ struct {
+ // CPUID 0x80000026.EBX
+ u32 amd_num_processors :16,
+ amd_power_eff_ranking :8,
+ amd_native_model_id :4,
+ amd_type :4;
+ };
+ };
};
struct cpuinfo_x86 {
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index aef70336d6247..795619ea13346 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -114,6 +114,12 @@ enum x86_topology_domains {
TOPO_MAX_DOMAIN,
};
+enum x86_topology_cpu_type {
+ TOPO_CPU_TYPE_PERFORMANCE,
+ TOPO_CPU_TYPE_EFFICIENCY,
+ TOPO_CPU_TYPE_UNKNOWN,
+};
+
struct x86_topology_system {
unsigned int dom_shifts[TOPO_MAX_DOMAIN];
unsigned int dom_size[TOPO_MAX_DOMAIN];
@@ -149,6 +155,9 @@ extern unsigned int __max_threads_per_core;
extern unsigned int __num_threads_per_package;
extern unsigned int __num_cores_per_package;
+const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c);
+enum x86_topology_cpu_type get_topology_generic_cpu_type(struct cpuinfo_x86 *c);
+
static inline unsigned int topology_max_packages(void)
{
return __max_logical_packages;
diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c
index 3baf3e4358347..10719aba62768 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, "cpu_type: %s\n", get_topology_cpu_type_name(c));
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_amd.c b/arch/x86/kernel/cpu/topology_amd.c
index 7d476fa697ca5..03b3c9c3a45e2 100644
--- a/arch/x86/kernel/cpu/topology_amd.c
+++ b/arch/x86/kernel/cpu/topology_amd.c
@@ -182,6 +182,9 @@ static void parse_topology_amd(struct topo_scan *tscan)
if (cpu_feature_enabled(X86_FEATURE_TOPOEXT))
has_topoext = cpu_parse_topology_ext(tscan);
+ if (cpu_feature_enabled(X86_FEATURE_AMD_HETEROGENEOUS_CORES))
+ tscan->c->topo.cpu_type = cpuid_ebx(0x80000026);
+
if (!has_topoext && !parse_8000_0008(tscan))
return;
diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
index 9a6069e7133c9..60d5d74189a30 100644
--- a/arch/x86/kernel/cpu/topology_common.c
+++ b/arch/x86/kernel/cpu/topology_common.c
@@ -3,6 +3,7 @@
#include <xen/xen.h>
+#include <asm/intel-family.h>
#include <asm/apic.h>
#include <asm/processor.h>
#include <asm/smp.h>
@@ -27,6 +28,36 @@ void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom,
}
}
+enum x86_topology_cpu_type get_topology_generic_cpu_type(struct cpuinfo_x86 *c)
+{
+ if (c->x86_vendor == X86_VENDOR_INTEL) {
+ switch (c->topo.intel_type) {
+ case INTEL_CPU_TYPE_ATOM: return TOPO_CPU_TYPE_EFFICIENCY;
+ case INTEL_CPU_TYPE_CORE: return TOPO_CPU_TYPE_PERFORMANCE;
+ }
+ }
+ if (c->x86_vendor == X86_VENDOR_AMD) {
+ switch (c->topo.amd_type) {
+ case 0: return TOPO_CPU_TYPE_PERFORMANCE;
+ case 1: return TOPO_CPU_TYPE_EFFICIENCY;
+ }
+ }
+
+ return TOPO_CPU_TYPE_UNKNOWN;
+}
+
+const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c)
+{
+ switch (get_topology_generic_cpu_type(c)) {
+ case TOPO_CPU_TYPE_PERFORMANCE:
+ return "performance";
+ case TOPO_CPU_TYPE_EFFICIENCY:
+ return "efficiency";
+ default:
+ return "unknown";
+ }
+}
+
static unsigned int __maybe_unused parse_num_cores_legacy(struct cpuinfo_x86 *c)
{
struct {
@@ -87,6 +118,7 @@ static void parse_topology(struct topo_scan *tscan, bool early)
.cu_id = 0xff,
.llc_id = BAD_APICID,
.l2c_id = BAD_APICID,
+ .cpu_type = TOPO_CPU_TYPE_UNKNOWN,
};
struct cpuinfo_x86 *c = tscan->c;
struct {
@@ -132,6 +164,8 @@ 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.cpu_type = cpuid_eax(0x1a);
break;
case X86_VENDOR_HYGON:
if (IS_ENABLED(CONFIG_CPU_SUP_HYGON))
--
2.43.0
