linux-kernel - [PATCH v2] x86/centaur: report correct CPU/cache topology

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Date:   Wed, 25 Apr 2018 16:48:30 +0800
From:   David Wang <davidwang@...oxin.com>
To:     <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
        <gregkh@...uxfoundation.org>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <brucechang@...-alliance.com>, <cooperyan@...oxin.com>,
        <qiyuanwang@...oxin.com>, <benjaminpan@...tech.com>,
        <lukelin@...cpu.com>, <timguo@...oxin.com>,
        David Wang <davidwang@...oxin.com>
Subject: [PATCH v2] x86/centaur: report correct CPU/cache topology

Centaur CPUs enumerate the cache topology in the same way as Intel CPUs,
but the functionality is unused so far.
The Centaur init code also misses to initialize x86_info::max_cores, so
the CPU topology can't be described correctly.

Initialize x86_cpuinfo:max_core and invoke init_intel_cacheinfo() to
make CPU and cache topology information avaliable and correct.

Signed-off-by: David Wang <davidwang@...oxin.com>

Changes from v1 to v2:
*1 replace centaur_num_cpu_cores with early_init_centaur_mc according to 
suggestions from tglx;
*2 call cpu_detect_cache_sizes when init_intel_cacheinfo returns 0. For
some very old Centaur CPUs can't support the mechanisms defined in init_
intel_cacheinfo.
 
---
 arch/x86/kernel/cpu/centaur.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
index 80d5110..367540b 100644
--- a/arch/x86/kernel/cpu/centaur.c
+++ b/arch/x86/kernel/cpu/centaur.c
@@ -96,8 +96,25 @@ enum {
 		EAMD3D		= 1<<20,
 };
 
+static void early_init_centaur_mc(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+	unsigned int eax, ebx, ecx, edx;
+
+	if (c->cpuid_level < 4)
+		return;
+
+	cpuid_count(4, 0, &eax, &ebx, &ecx, &edx);
+	if (eax & 0x1f)
+		c->x86_max_cores = (eax >> 26) + 1;
+	else
+		return;
+#endif
+}
+
 static void early_init_centaur(struct cpuinfo_x86 *c)
 {
+	early_init_centaur_mc(c);
 	switch (c->x86) {
 #ifdef CONFIG_X86_32
 	case 5:
@@ -146,6 +163,7 @@ static void centaur_detect_vmx_virtcap(struct cpuinfo_x86 *c)
 
 static void init_centaur(struct cpuinfo_x86 *c)
 {
+	unsigned int l2 = 0;
 #ifdef CONFIG_X86_32
 	char *name;
 	u32  fcr_set = 0;
@@ -161,6 +179,17 @@ static void init_centaur(struct cpuinfo_x86 *c)
 #endif
 	early_init_centaur(c);
 
+	l2 = init_intel_cacheinfo(c);
+
+	/* Detect legacy cache sizes if init_intel_cacheinfo did not */
+	if (l2 == 0) {
+		cpu_detect_cache_sizes(c);
+	}
+
+#ifdef CONFIG_X86_32
+	detect_ht(c);
+#endif
+
 	if (c->cpuid_level > 9) {
 		unsigned int eax = cpuid_eax(10);
 
-- 
1.9.1