On Wed, Oct 23, 2024 at 12:43:56PM -0500, Mario Limonciello wrote:
> 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(+)
Except the minor touchup below, I don't have any complaints about this
anymore.
Intel folks?
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 795619ea1334..9f9376db64e3 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -156,7 +156,7 @@ 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);
+enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c);
static inline unsigned int topology_max_packages(void)
{
diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
index 60d5d74189a3..8277c64f88db 100644
--- a/arch/x86/kernel/cpu/topology_common.c
+++ b/arch/x86/kernel/cpu/topology_common.c
@@ -28,7 +28,7 @@ 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)
+enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c)
{
if (c->x86_vendor == X86_VENDOR_INTEL) {
switch (c->topo.intel_type) {
@@ -48,7 +48,7 @@ enum x86_topology_cpu_type get_topology_generic_cpu_type(struct cpuinfo_x86 *c)
const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c)
{
- switch (get_topology_generic_cpu_type(c)) {
+ switch (get_topology_cpu_type(c)) {
case TOPO_CPU_TYPE_PERFORMANCE:
return "performance";
case TOPO_CPU_TYPE_EFFICIENCY:
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
