From ddc5681ed33a279fdc188e98e71f0c539f08c6e6 Mon Sep 17 00:00:00 2001 From: Shai Fultheim Date: Fri, 20 Apr 2012 01:09:11 +0300 Subject: [PATCH] x86/cache_info: Fix setup of l2/l3 ids On some architectures (such as vSMP), it is possible to have CPUs with a different number of cores sharing the same cache. The current implementation implicitly assumes that all CPUs will have the same number of cores sharing caches, and as a result, different CPUs can end up with the same l2/l3 ids. Fix this by masking out the shared cache bits, instead of shifting the APICID. By doing so, it is guaranteed that the generated cache ids are always unique. Signed-off-by: Shai Fultheim [ rebased, simplified, and reworded the commit message] Signed-off-by: Ido Yariv Cc: Borislav Petkov Cc: Andreas Herrmann Cc: Mike Travis Cc: Dave Jones Link: http://lkml.kernel.org/r/1334873351-31142-1-git-send-email-ido@wizery.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/intel_cacheinfo.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index b8f3653..9a7c90d 100644 --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -615,14 +615,14 @@ unsigned int __cpuinit init_intel_cacheinfo(struct cpuinfo_x86 *c) new_l2 = this_leaf.size/1024; num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; index_msb = get_count_order(num_threads_sharing); - l2_id = c->apicid >> index_msb; + l2_id = c->apicid & ~((1 << index_msb) - 1); break; case 3: new_l3 = this_leaf.size/1024; num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; index_msb = get_count_order( num_threads_sharing); - l3_id = c->apicid >> index_msb; + l3_id = c->apicid & ~((1 << index_msb) - 1); break; default: break; -- 2.7.4