[PATCH v4 03/18] x86, intel_cacheinfo: Enable cache id in x86

From: Fenghua Yu
Date: Fri Oct 14 2016 - 19:16:21 EST


From: Fenghua Yu <fenghua.yu@xxxxxxxxx>

Cache id is retrieved from APIC ID and CPUID leaf 4 on x86.

For more details see the section on "Cache ID Extraction Parameters" in
"Intel 64 Architecture Processor Topology Enumeration" at
https://software.intel.com/sites/default/files/63/1a/Kuo_CpuTopology_rc1.rh1.final.pdf

Also "Intel 64 and IA-32 Architectures Software Developer's Manual" volume 2,
table 3-18 "information Returned by CPUID Instruction" at
http://www.intel.com/sdm

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
arch/x86/kernel/cpu/intel_cacheinfo.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index de6626c..8dc5720 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -153,6 +153,7 @@ struct _cpuid4_info_regs {
union _cpuid4_leaf_eax eax;
union _cpuid4_leaf_ebx ebx;
union _cpuid4_leaf_ecx ecx;
+ unsigned int id;
unsigned long size;
struct amd_northbridge *nb;
};
@@ -894,6 +895,8 @@ static void __cache_cpumap_setup(unsigned int cpu, int index,
static void ci_leaf_init(struct cacheinfo *this_leaf,
struct _cpuid4_info_regs *base)
{
+ this_leaf->id = base->id;
+ this_leaf->attributes = CACHE_ID;
this_leaf->level = base->eax.split.level;
this_leaf->type = cache_type_map[base->eax.split.type];
this_leaf->coherency_line_size =
@@ -920,6 +923,22 @@ static int __init_cache_level(unsigned int cpu)
return 0;
}

+/*
+ * The max shared threads number comes from CPUID.4:EAX[25-14] with input
+ * ECX as cache index. Then right shift apicid by the number's order to get
+ * cache id for this cache node.
+ */
+static void get_cache_id(int cpu, struct _cpuid4_info_regs *id4_regs)
+{
+ struct cpuinfo_x86 *c = &cpu_data(cpu);
+ unsigned long num_threads_sharing;
+ int index_msb;
+
+ num_threads_sharing = 1 + id4_regs->eax.split.num_threads_sharing;
+ index_msb = get_count_order(num_threads_sharing);
+ id4_regs->id = c->apicid >> index_msb;
+}
+
static int __populate_cache_leaves(unsigned int cpu)
{
unsigned int idx, ret;
@@ -931,6 +950,7 @@ static int __populate_cache_leaves(unsigned int cpu)
ret = cpuid4_cache_lookup_regs(idx, &id4_regs);
if (ret)
return ret;
+ get_cache_id(cpu, &id4_regs);
ci_leaf_init(this_leaf++, &id4_regs);
__cache_cpumap_setup(cpu, idx, &id4_regs);
}
--
2.5.0