diff options
| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2024-10-25 12:14:58 -0500 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-10-25 20:44:26 +0200 |
| commit | 45239ba39a5279e9efc671774e2eef29df4d2484 (patch) | |
| tree | 1dca9e92e9d1566d0d76d960a5df4e36137ac1c7 /arch/x86/kernel/cpu/topology_amd.c | |
| parent | b0979e53645825a38f814ca5d3d09aed2745911d (diff) | |
x86/cpu: Add CPU type to struct cpuinfo_topology
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@linux.intel.com>
Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20241025171459.1093-5-mario.limonciello@amd.com
Diffstat (limited to 'arch/x86/kernel/cpu/topology_amd.c')
| -rw-r--r-- | arch/x86/kernel/cpu/topology_amd.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/topology_amd.c b/arch/x86/kernel/cpu/topology_amd.c index 7d476fa697ca..03b3c9c3a45e 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; |