From 2a2261553dd1472ca574acadbd93e12f44c4e6d5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 22 Jul 2014 15:35:14 +0200 Subject: 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 Cc: Dietmar Eggemann Tested-by: Bruno Wolff III Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140722133514.GM12054@laptop.lan Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/intel.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) (limited to 'arch/x86/kernel/cpu/intel.c') diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index a80029035bf..f9e4fdd3b87 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); -- cgit v1.2.3-70-g09d2