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The existing x86_match_cpu() infrastructure can be used to match a bunch of attributes of a CPU: vendor, family, model, steppings and CPU features. But, there's one more attribute that's missing and unable to be matched against: the platform ID, enumerated on Intel CPUs in MSR_IA32_PLATFORM_ID. It is a little more obscure and is only queried during microcode loading. This is because Intel sometimes has CPUs with identical family/model/stepping but which need different microcode. These CPUs are differentiated with the platform ID. Add a field in 'struct x86_cpu_id' for the platform ID. Similar to the stepping field, make the new field a mask of platform IDs. Some examples: 0x01: matches only platform ID 0x0 0x02: matches only platform ID 0x1 0x03: matches platform IDs 0x0 or 0x1 0x80: matches only platform ID 0x7 0xff: matches all 8 possible platform IDs Since the mask is only a byte wide, it nestles in next to another u8 and does not even increase the size of 'struct x86_cpu_id'. Reserve the all 0's value as the wildcard (X86_PLATFORM_ANY). This avoids forcing changes to existing 'struct x86_cpu_id' users. They can just continue to fill the field with 0's and their matching will work exactly as before. Note: If someone is ever looking for space in 'struct x86_cpu_id', this new field could probably get stuck over in ->driver_data for the one user that there is. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://patch.msgid.link/20260304181022.058DF07C@davehans-spike.ostc.intel.com
102 lines
3.3 KiB
C
102 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <asm/cpu_device_id.h>
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#include <asm/cpufeature.h>
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#include <linux/cpu.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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/**
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* x86_match_vendor_cpu_type - helper function to match the hardware defined
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* cpu-type for a single entry in the x86_cpu_id
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* table. Note, this function does not match the
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* generic cpu-types TOPO_CPU_TYPE_EFFICIENCY and
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* TOPO_CPU_TYPE_PERFORMANCE.
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* @c: Pointer to the cpuinfo_x86 structure of the CPU to match.
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* @m: Pointer to the x86_cpu_id entry to match against.
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*
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* Return: true if the cpu-type matches, false otherwise.
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*/
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static bool x86_match_vendor_cpu_type(struct cpuinfo_x86 *c, const struct x86_cpu_id *m)
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{
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if (m->type == X86_CPU_TYPE_ANY)
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return true;
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/* Hybrid CPUs are special, they are assumed to match all cpu-types */
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if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
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return true;
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if (c->x86_vendor == X86_VENDOR_INTEL)
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return m->type == c->topo.intel_type;
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if (c->x86_vendor == X86_VENDOR_AMD)
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return m->type == c->topo.amd_type;
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return false;
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}
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/**
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* x86_match_cpu - match current CPU against an array of x86_cpu_ids
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* @match: Pointer to array of x86_cpu_ids. Last entry terminated with
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* {}.
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*
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* Return the entry if the current CPU matches the entries in the
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* passed x86_cpu_id match table. Otherwise NULL. The match table
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* contains vendor (X86_VENDOR_*), family, model and feature bits or
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* respective wildcard entries.
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*
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* A typical table entry would be to match a specific CPU
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*
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* X86_MATCH_VFM_FEATURE(INTEL_BROADWELL, X86_FEATURE_ANY, NULL);
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*
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* Fields can be wildcarded with %X86_VENDOR_ANY, %X86_FAMILY_ANY,
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* %X86_MODEL_ANY, %X86_FEATURE_ANY (except for vendor)
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*
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* asm/cpu_device_id.h contains a set of useful macros which are shortcuts
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* for various common selections. The above can be shortened to:
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*
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* X86_MATCH_VFM(INTEL_BROADWELL, NULL);
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*
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* Arrays used to match for this should also be declared using
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* MODULE_DEVICE_TABLE(x86cpu, ...)
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*
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* This always matches against the boot cpu, assuming models and features are
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* consistent over all CPUs.
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*/
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const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
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{
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const struct x86_cpu_id *m;
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struct cpuinfo_x86 *c = &boot_cpu_data;
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for (m = match; m->flags & X86_CPU_ID_FLAG_ENTRY_VALID; m++) {
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if (m->vendor != X86_VENDOR_ANY && c->x86_vendor != m->vendor)
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continue;
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if (m->family != X86_FAMILY_ANY && c->x86 != m->family)
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continue;
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if (m->model != X86_MODEL_ANY && c->x86_model != m->model)
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continue;
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if (m->steppings != X86_STEPPING_ANY &&
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!(BIT(c->x86_stepping) & m->steppings))
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continue;
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if (m->platform_mask != X86_PLATFORM_ANY &&
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!(BIT(c->intel_platform_id) & m->platform_mask))
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continue;
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if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature))
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continue;
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if (!x86_match_vendor_cpu_type(c, m))
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continue;
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return m;
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}
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return NULL;
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}
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EXPORT_SYMBOL(x86_match_cpu);
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bool x86_match_min_microcode_rev(const struct x86_cpu_id *table)
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{
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const struct x86_cpu_id *res = x86_match_cpu(table);
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if (!res || res->driver_data > boot_cpu_data.microcode)
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return false;
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return true;
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}
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EXPORT_SYMBOL_GPL(x86_match_min_microcode_rev);
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