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From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, bp@suse.de,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [PATCH] x86/CPU/AMD: Fix LLC ID bit-shift calculation
Date: Wed, 13 Jun 2018 13:43:10 -0500
Message-ID: <1528915390-30533-1-git-send-email-suravee.suthikulpanit@amd.com> (raw)

The current logic incorrectly calculates the LLC ID from the APIC ID.
Unless specified otherwise, the LLC ID should be calculated from
the count order of the number of threads sharing cache.

Fixes: 68091ee7ac3c ("Calculate last level cache ID from number of sharing threads")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 arch/x86/kernel/cpu/cacheinfo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 38354c6..0c5fcbd 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -671,7 +671,7 @@ void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, int cpu, u8 node_id)
 			num_sharing_cache = ((eax >> 14) & 0xfff) + 1;
 
 		if (num_sharing_cache) {
-			int bits = get_count_order(num_sharing_cache) - 1;
+			int bits = get_count_order(num_sharing_cache);
 
 			per_cpu(cpu_llc_id, cpu) = c->apicid >> bits;
 		}
-- 
2.7.4


             reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-13 18:43 Suravee Suthikulpanit [this message]
2018-06-18 17:20 ` Borislav Petkov
2018-06-18 18:14   ` Suthikulpanit, Suravee
2018-06-18 18:23     ` Borislav Petkov
2018-06-18 18:46       ` Suthikulpanit, Suravee
2018-06-18 18:57         ` Borislav Petkov
2018-06-22 19:24 ` [tip:x86/urgent] " tip-bot for Suravee Suthikulpanit

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