xref: /linux/arch/x86/kernel/cpu/scattered.c (revision c0c914eca7f251c70facc37dfebeaf176601918d) 
1 /*
2  *	Routines to identify additional cpu features that are scattered in
3  *	cpuid space.
4  */
5 #include <linux/cpu.h>
6 
7 #include <asm/pat.h>
8 #include <asm/processor.h>
9 
10 #include <asm/apic.h>
11 
12 struct cpuid_bit {
13 	u16 feature;
14 	u8 reg;
15 	u8 bit;
16 	u32 level;
17 	u32 sub_leaf;
18 };
19 
20 enum cpuid_regs {
21 	CR_EAX = 0,
22 	CR_ECX,
23 	CR_EDX,
24 	CR_EBX
25 };
26 
27 void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
28 {
29 	u32 max_level;
30 	u32 regs[4];
31 	const struct cpuid_bit *cb;
32 
33 	static const struct cpuid_bit cpuid_bits[] = {
34 		{ X86_FEATURE_INTEL_PT,		CR_EBX,25, 0x00000007, 0 },
35 		{ X86_FEATURE_APERFMPERF,	CR_ECX, 0, 0x00000006, 0 },
36 		{ X86_FEATURE_EPB,		CR_ECX, 3, 0x00000006, 0 },
37 		{ X86_FEATURE_HW_PSTATE,	CR_EDX, 7, 0x80000007, 0 },
38 		{ X86_FEATURE_CPB,		CR_EDX, 9, 0x80000007, 0 },
39 		{ X86_FEATURE_PROC_FEEDBACK,	CR_EDX,11, 0x80000007, 0 },
40 		{ 0, 0, 0, 0, 0 }
41 	};
42 
43 	for (cb = cpuid_bits; cb->feature; cb++) {
44 
45 		/* Verify that the level is valid */
46 		max_level = cpuid_eax(cb->level & 0xffff0000);
47 		if (max_level < cb->level ||
48 		    max_level > (cb->level | 0xffff))
49 			continue;
50 
51 		cpuid_count(cb->level, cb->sub_leaf, &regs[CR_EAX],
52 			    &regs[CR_EBX], &regs[CR_ECX], &regs[CR_EDX]);
53 
54 		if (regs[cb->reg] & (1 << cb->bit))
55 			set_cpu_cap(c, cb->feature);
56 	}
57 }
58