[PATCH v4 1/2] cpuid: Add a helper in scattered.c to return cpuid leaf info

[He Chen <he.chen@linux.intel.com>]

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. Also, export
enum cpuid_regs in pt.c and scattered.c to enum cpuid_regs_idx in
processor.h.
---
 arch/x86/events/intel/pt.c       | 45 ++++++++++++++------------------
 arch/x86/include/asm/processor.h | 14 ++++++++++
 arch/x86/kernel/cpu/scattered.c  | 56 ++++++++++++++++++++++++++--------------
 arch/x86/kernel/cpuid.c          |  4 ---
 4 files changed, 70 insertions(+), 49 deletions(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index c5047b8..1c1b9fe 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -36,13 +36,6 @@ static DEFINE_PER_CPU(struct pt, pt_ctx);
 
 static struct pt_pmu pt_pmu;
 
-enum cpuid_regs {
-	CR_EAX = 0,
-	CR_ECX,
-	CR_EDX,
-	CR_EBX
-};
-
 /*
  * Capabilities of Intel PT hardware, such as number of address bits or
  * supported output schemes, are cached and exported to userspace as "caps"
@@ -64,21 +57,21 @@ static struct pt_cap_desc {
 	u8		reg;
 	u32		mask;
 } pt_caps[] = {
-	PT_CAP(max_subleaf,		0, CR_EAX, 0xffffffff),
-	PT_CAP(cr3_filtering,		0, CR_EBX, BIT(0)),
-	PT_CAP(psb_cyc,			0, CR_EBX, BIT(1)),
-	PT_CAP(ip_filtering,		0, CR_EBX, BIT(2)),
-	PT_CAP(mtc,			0, CR_EBX, BIT(3)),
-	PT_CAP(ptwrite,			0, CR_EBX, BIT(4)),
-	PT_CAP(power_event_trace,	0, CR_EBX, BIT(5)),
-	PT_CAP(topa_output,		0, CR_ECX, BIT(0)),
-	PT_CAP(topa_multiple_entries,	0, CR_ECX, BIT(1)),
-	PT_CAP(single_range_output,	0, CR_ECX, BIT(2)),
-	PT_CAP(payloads_lip,		0, CR_ECX, BIT(31)),
-	PT_CAP(num_address_ranges,	1, CR_EAX, 0x3),
-	PT_CAP(mtc_periods,		1, CR_EAX, 0xffff0000),
-	PT_CAP(cycle_thresholds,	1, CR_EBX, 0xffff),
-	PT_CAP(psb_periods,		1, CR_EBX, 0xffff0000),
+	PT_CAP(max_subleaf,		0, CPUID_EAX, 0xffffffff),
+	PT_CAP(cr3_filtering,		0, CPUID_EBX, BIT(0)),
+	PT_CAP(psb_cyc,			0, CPUID_EBX, BIT(1)),
+	PT_CAP(ip_filtering,		0, CPUID_EBX, BIT(2)),
+	PT_CAP(mtc,			0, CPUID_EBX, BIT(3)),
+	PT_CAP(ptwrite,			0, CPUID_EBX, BIT(4)),
+	PT_CAP(power_event_trace,	0, CPUID_EBX, BIT(5)),
+	PT_CAP(topa_output,		0, CPUID_ECX, BIT(0)),
+	PT_CAP(topa_multiple_entries,	0, CPUID_ECX, BIT(1)),
+	PT_CAP(single_range_output,	0, CPUID_ECX, BIT(2)),
+	PT_CAP(payloads_lip,		0, CPUID_ECX, BIT(31)),
+	PT_CAP(num_address_ranges,	1, CPUID_EAX, 0x3),
+	PT_CAP(mtc_periods,		1, CPUID_EAX, 0xffff0000),
+	PT_CAP(cycle_thresholds,	1, CPUID_EBX, 0xffff),
+	PT_CAP(psb_periods,		1, CPUID_EBX, 0xffff0000),
 };
 
 static u32 pt_cap_get(enum pt_capabilities cap)
@@ -213,10 +206,10 @@ static int __init pt_pmu_hw_init(void)
 
 	for (i = 0; i < PT_CPUID_LEAVES; i++) {
 		cpuid_count(20, i,
-			    &pt_pmu.caps[CR_EAX + i*PT_CPUID_REGS_NUM],
-			    &pt_pmu.caps[CR_EBX + i*PT_CPUID_REGS_NUM],
-			    &pt_pmu.caps[CR_ECX + i*PT_CPUID_REGS_NUM],
-			    &pt_pmu.caps[CR_EDX + i*PT_CPUID_REGS_NUM]);
+			    &pt_pmu.caps[CPUID_EAX + i*PT_CPUID_REGS_NUM],
+			    &pt_pmu.caps[CPUID_EBX + i*PT_CPUID_REGS_NUM],
+			    &pt_pmu.caps[CPUID_ECX + i*PT_CPUID_REGS_NUM],
+			    &pt_pmu.caps[CPUID_EDX + i*PT_CPUID_REGS_NUM]);
 	}
 
 	ret = -ENOMEM;
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 984a7bf..e7f8c62 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -137,6 +137,17 @@ struct cpuinfo_x86 {
 	u32			microcode;
 };
 
+struct cpuid_regs {
+	u32 eax, ebx, ecx, edx;
+};
+
+enum cpuid_regs_idx {
+	CPUID_EAX = 0,
+	CPUID_EBX,
+	CPUID_ECX,
+	CPUID_EDX,
+};
+
 #define X86_VENDOR_INTEL	0
 #define X86_VENDOR_CYRIX	1
 #define X86_VENDOR_AMD		2
@@ -178,6 +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 1db8dc4..ef131ea 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -17,11 +17,17 @@ struct cpuid_bit {
 	u32 sub_leaf;
 };
 
-enum cpuid_regs {
-	CR_EAX = 0,
-	CR_ECX,
-	CR_EDX,
-	CR_EBX
+/* 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)
@@ -30,18 +36,6 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
 	u32 regs[4];
 	const struct cpuid_bit *cb;
 
-	static const struct cpuid_bit cpuid_bits[] = {
-		{ X86_FEATURE_INTEL_PT,		CR_EBX,25, 0x00000007, 0 },
-		{ X86_FEATURE_AVX512_4VNNIW,	CR_EDX, 2, 0x00000007, 0 },
-		{ X86_FEATURE_AVX512_4FMAPS,	CR_EDX, 3, 0x00000007, 0 },
-		{ X86_FEATURE_APERFMPERF,	CR_ECX, 0, 0x00000006, 0 },
-		{ X86_FEATURE_EPB,		CR_ECX, 3, 0x00000006, 0 },
-		{ X86_FEATURE_HW_PSTATE,	CR_EDX, 7, 0x80000007, 0 },
-		{ X86_FEATURE_CPB,		CR_EDX, 9, 0x80000007, 0 },
-		{ X86_FEATURE_PROC_FEEDBACK,	CR_EDX,11, 0x80000007, 0 },
-		{ 0, 0, 0, 0, 0 }
-	};
-
 	for (cb = cpuid_bits; cb->feature; cb++) {
 
 		/* Verify that the level is valid */
@@ -50,10 +44,34 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
 		    max_level > (cb->level | 0xffff))
 			continue;
 
-		cpuid_count(cb->level, cb->sub_leaf, &regs[CR_EAX],
-			    &regs[CR_EBX], &regs[CR_ECX], &regs[CR_EDX]);
+		cpuid_count(cb->level, cb->sub_leaf, &regs[CPUID_EAX],
+			    &regs[CPUID_EBX], &regs[CPUID_ECX], &regs[CPUID_EDX]);
 
 		if (regs[cb->reg] & (1 << cb->bit))
 			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);
diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 2836de3..9095c80 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -46,10 +46,6 @@
 
 static struct class *cpuid_class;
 
-struct cpuid_regs {
-	u32 eax, ebx, ecx, edx;
-};
-
 static void cpuid_smp_cpuid(void *cmd_block)
 {
 	struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block;
-- 
2.7.4