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authorPeter Zijlstra <peterz@infradead.org>2014-07-22 17:35:14 +0400
committerH. Peter Anvin <hpa@zytor.com>2014-07-23 19:16:17 +0400
commit2a2261553dd1472ca574acadbd93e12f44c4e6d5 (patch)
tree4b5b580463c2358ca80a25685dc5c88f365c1047 /arch
parent8142b215501f8b291a108a202b3a053a265b03dd (diff)
downloadlinux-2a2261553dd1472ca574acadbd93e12f44c4e6d5.tar.xz
x86, cpu: Fix cache topology for early P4-SMT
P4 systems with cpuid level < 4 can have SMT, but the cache topology description available (cpuid2) does not include SMP information. Now we know that SMT shares all cache levels, and therefore we can mark all available cache levels as shared. We do this by setting cpu_llc_id to ->phys_proc_id, since that's the same for each SMT thread. We can do this unconditional since if there's no SMT its still true, the one CPU shares cache with only itself. This fixes a problem where such CPUs report an incorrect LLC CPU mask. This in turn fixes a crash in the scheduler where the topology was build wrong, it assumes the LLC mask to include at least the SMT CPUs. Cc: Josh Boyer <jwboyer@redhat.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140722133514.GM12054@laptop.lan Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/intel.c22
-rw-r--r--arch/x86/kernel/cpu/intel_cacheinfo.c12
2 files changed, 23 insertions, 11 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index a80029035bf2..f9e4fdd3b877 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -370,6 +370,17 @@ static void init_intel(struct cpuinfo_x86 *c)
*/
detect_extended_topology(c);
+ if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
+ /*
+ * let's use the legacy cpuid vector 0x1 and 0x4 for topology
+ * detection.
+ */
+ c->x86_max_cores = intel_num_cpu_cores(c);
+#ifdef CONFIG_X86_32
+ detect_ht(c);
+#endif
+ }
+
l2 = init_intel_cacheinfo(c);
if (c->cpuid_level > 9) {
unsigned eax = cpuid_eax(10);
@@ -438,17 +449,6 @@ static void init_intel(struct cpuinfo_x86 *c)
set_cpu_cap(c, X86_FEATURE_P3);
#endif
- if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
- /*
- * let's use the legacy cpuid vector 0x1 and 0x4 for topology
- * detection.
- */
- c->x86_max_cores = intel_num_cpu_cores(c);
-#ifdef CONFIG_X86_32
- detect_ht(c);
-#endif
- }
-
/* Work around errata */
srat_detect_node(c);
diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index a952e9c85b6f..9c8f7394c612 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -730,6 +730,18 @@ unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c)
#endif
}
+#ifdef CONFIG_X86_HT
+ /*
+ * If cpu_llc_id is not yet set, this means cpuid_level < 4 which in
+ * turns means that the only possibility is SMT (as indicated in
+ * cpuid1). Since cpuid2 doesn't specify shared caches, and we know
+ * that SMT shares all caches, we can unconditionally set cpu_llc_id to
+ * c->phys_proc_id.
+ */
+ if (per_cpu(cpu_llc_id, cpu) == BAD_APICID)
+ per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
+#endif
+
c->x86_cache_size = l3 ? l3 : (l2 ? l2 : (l1i+l1d));
return l2;