[PATCH] i386/x86-64: Use new official CPUID to get APICID/core split on AMD platforms

[mirror_ubuntu-artful-kernel.git] / arch / i386 / kernel / cpu / amd.c

diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 786d1a57048b9156396a7f7d5739306097420c60..b9c93d9789e719e64e98f5cb6aed99bc0cd30546 100644 (file)
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -224,15 +224,17 @@ static void __init init_amd(struct cpuinfo_x86 *c)
 
 #ifdef CONFIG_X86_HT
        /*
-        * On a AMD dual core setup the lower bits of the APIC id
-        * distingush the cores.  Assumes number of cores is a power
-        * of two.
+        * On a AMD multi core setup the lower bits of the APIC id
+        * distingush the cores.
         */
        if (c->x86_max_cores > 1) {
                int cpu = smp_processor_id();
-               unsigned bits = 0;
-               while ((1 << bits) < c->x86_max_cores)
-                       bits++;
+               unsigned bits = (cpuid_ecx(0x80000008) >> 12) & 0xf;
+
+               if (bits == 0) {
+                       while ((1 << bits) < c->x86_max_cores)
+                               bits++;
+               }
                cpu_core_id[cpu] = phys_proc_id[cpu] & ((1<<bits)-1);
                phys_proc_id[cpu] >>= bits;
                printk(KERN_INFO "CPU %d(%d) -> Core %d\n",