Some sparse CPUID leafs are gathered in a fake leaf to save size of
x86_capability array in current code, but sometimes, kernel or other
modules (e.g. KVM cpuid enumeration) may need actual hardware leaf
information.
This patch adds a helper get_scattered_cpuid_leaf() to rebuild actual
CPUID leaf, and it can be called outside by modules.
Signed-off-by: He Chen <he.chen@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 3 +++
arch/x86/kernel/cpu/scattered.c | 49 ++++++++++++++++++++++++++++++----------
2 files changed, 40 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 8f6ac5b..e7f8c62 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -189,6 +189,9 @@ extern void identify_secondary_cpu(struct cpuinfo_x86 *);
extern void print_cpu_info(struct cpuinfo_x86 *);
void print_cpu_msr(struct cpuinfo_x86 *);
extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
+extern u32 get_scattered_cpuid_leaf(unsigned int level,
+ unsigned int sub_leaf,
+ enum cpuid_regs_idx reg);
extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 5dbdd0b..d1316f9 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -17,24 +17,25 @@ struct cpuid_bit {
u32 sub_leaf;
};
+/* Please keep the leaf sorted by cpuid_bit.level for faster search. */
+static const struct cpuid_bit cpuid_bits[] = {
+ { X86_FEATURE_APERFMPERF, CPUID_ECX, 0, 0x00000006, 0 },
+ { X86_FEATURE_EPB, CPUID_ECX, 3, 0x00000006, 0 },
+ { X86_FEATURE_INTEL_PT, CPUID_EBX, 25, 0x00000007, 0 },
+ { X86_FEATURE_AVX512_4VNNIW, CPUID_EDX, 2, 0x00000007, 0 },
+ { X86_FEATURE_AVX512_4FMAPS, CPUID_EDX, 3, 0x00000007, 0 },
+ { X86_FEATURE_HW_PSTATE, CPUID_EDX, 7, 0x80000007, 0 },
+ { X86_FEATURE_CPB, CPUID_EDX, 9, 0x80000007, 0 },
+ { X86_FEATURE_PROC_FEEDBACK, CPUID_EDX, 11, 0x80000007, 0 },
+ { 0, 0, 0, 0, 0 }
+};
+
void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
{
u32 max_level;
u32 regs[4];
const struct cpuid_bit *cb;
- static const struct cpuid_bit cpuid_bits[] = {
- { X86_FEATURE_INTEL_PT, CPUID_EBX,25, 0x00000007, 0 },
- { X86_FEATURE_AVX512_4VNNIW, CPUID_EDX, 2, 0x00000007, 0 },
- { X86_FEATURE_AVX512_4FMAPS, CPUID_EDX, 3, 0x00000007, 0 },
- { X86_FEATURE_APERFMPERF, CPUID_ECX, 0, 0x00000006, 0 },
- { X86_FEATURE_EPB, CPUID_ECX, 3, 0x00000006, 0 },
- { X86_FEATURE_HW_PSTATE, CPUID_EDX, 7, 0x80000007, 0 },
- { X86_FEATURE_CPB, CPUID_EDX, 9, 0x80000007, 0 },
- { X86_FEATURE_PROC_FEEDBACK, CPUID_EDX,11, 0x80000007, 0 },
- { 0, 0, 0, 0, 0 }
- };
-
for (cb = cpuid_bits; cb->feature; cb++) {
/* Verify that the level is valid */
@@ -51,3 +52,27 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
set_cpu_cap(c, cb->feature);
}
}
+
+u32 get_scattered_cpuid_leaf(unsigned int level, unsigned int sub_leaf,
+ enum cpuid_regs_idx reg)
+{
+ const struct cpuid_bit *cb;
+ u32 cpuid_val = 0;
+
+ for (cb = cpuid_bits; cb->feature; cb++) {
+
+ if (level > cb->level)
+ continue;
+
+ if (level < cb->level)
+ break;
+
+ if (reg == cb->reg && sub_leaf == cb->sub_leaf) {
+ if (cpu_has(&boot_cpu_data, cb->feature))
+ cpuid_val |= BIT(cb->bit);
+ }
+ }
+
+ return cpuid_val;
+}
+EXPORT_SYMBOL_GPL(get_scattered_cpuid_leaf);
--
2.7.4
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