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Date: Fri, 20 Apr 2012 01:09:11 +0300 From: Ido Yariv <ido@...ery.com> To: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com> Cc: Shai Fultheim <shai@...lemp.com>, Ido Yariv <ido@...ery.com> Subject: [PATCH RESEND] x86: cache_info: Fix setup of l2/l3 ids From: Shai Fultheim <shai@...lemp.com> 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 <shai@...lemp.com> [ido@...ery.com: rebased, simplified, and reworded the commit message] Signed-off-by: Ido Yariv <ido@...ery.com> --- arch/x86/kernel/cpu/intel_cacheinfo.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index 73d08ed..caa6cb0 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; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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