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x86/CPU/AMD: Fix LLC ID bit-shift calculation 

The current logic incorrectly calculates the LLC ID from the APIC ID.

Unless specified otherwise, the LLC ID should be calculated by removing
the Core and Thread ID bits from the least significant end of the APIC
ID. For more info, see "ApicId Enumeration Requirements" in any Fam17h
PPR document.

[ bp: Improve commit message. ]

Fixes: 68091ee7ac ("Calculate last level cache ID from number of sharing threads")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1528915390-30533-1-git-send-email-suravee.suthikulpanit@amd.com
This commit is contained in:
Suravee Suthikulpanit 2018-06-13 13:43:10 -05:00 committed by Thomas Gleixner
parent 7731b8bc94
commit 964d978433
1 changed files with 1 additions and 1 deletions
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arch/x86/kernel/cpu/cacheinfo.c
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@ -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;
}