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: 68091ee7ac3c ("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

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 38354c66df81144b7d2998ee42fce7a6b15485cd..0c5fcbd998cf11badefad906a2122400a3512d58 100644 (file)
--- 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;
                }