[PATCH] Add support for NUMA discovery on AMD dual core to x86-64

Following the CPUID extensions and APIC-ID setup presented by Richard
Brunner at Kernel Summit.

Without this the kernel's node discovery would assign the wrong nodes on
dual core systems and cause performance degradation.

Only handles power of two cored CPUs, others will be ignored.

/proc/cpuinfo has a new field cpu cores: <number of CPU cores> and also
show the other core as HT sibling (this is needed to make old CPU based
license managers to count one CPU package as only one physical CPU)

FIXME this currently misses the disable code for SMT idle.  That's because
2.6.9rc1-bk6 removed the arch hooks need for that.  Needs to be readded
later.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 35 insertions, 2 deletions

diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 24b2f7806d06..377856a905c1 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -681,6 +681,26 @@ static int __init init_amd(struct cpuinfo_x86 *c)
 		} 
 	} 
 	display_cacheinfo(c);
+
+	if (c->cpuid_level >= 0x80000008) {
+		c->x86_num_cores = (cpuid_ecx(0x80000008) & 0xff) + 1;
+		if (c->x86_num_cores & (c->x86_num_cores - 1))
+			c->x86_num_cores = 1;
+
+#ifdef CONFIG_NUMA
+		/* On a dual core setup the lower bits of apic id
+		   distingush the cores. Fix up the CPU<->node mappings
+		   here based on that.
+		   Assumes number of cores is a power of two. */
+		if (c->x86_num_cores > 1) {
+			int cpu = c->x86_apicid;
+			cpu_to_node[cpu] = cpu >> hweight32(c->x86_num_cores - 1);
+			printk(KERN_INFO "CPU %d -> Node %d\n",
+			       cpu, cpu_to_node[cpu]);
+		}
+#endif
+	}
+
 	return r;
 }
 
@@ -905,6 +925,8 @@ void __init early_identify_cpu(struct cpuinfo_x86 *c)
 	c->x86_model_id[0] = '\0';  /* Unset */
 	c->x86_clflush_size = 64;
 	c->x86_cache_alignment = c->x86_clflush_size;
+	c->x86_num_cores = 1;
+	c->x86_apicid = c == &boot_cpu_data ? 0 : c - cpu_data;
 	memset(&c->x86_capability, 0, sizeof c->x86_capability);
 
 	/* Get vendor name */
@@ -932,6 +954,7 @@ void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		} 
 		if (c->x86_capability[0] & (1<<19)) 
 			c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
+		c->x86_apicid = misc >> 24;
 	} else {
 		/* Have CPUID level 0 only - unheard of */
 		c->x86 = 4;
@@ -951,8 +974,10 @@ void __init identify_cpu(struct cpuinfo_x86 *c)
 	/* AMD-defined flags: level 0x80000001 */
 	xlvl = cpuid_eax(0x80000000);
 	if ( (xlvl & 0xffff0000) == 0x80000000 ) {
-		if ( xlvl >= 0x80000001 )
+		if ( xlvl >= 0x80000001 ) {
 			c->x86_capability[1] = cpuid_edx(0x80000001);
+			c->x86_capability[5] = cpuid_ecx(0x80000001);
+		}
 		if ( xlvl >= 0x80000004 )
 			get_model_name(c); /* Default name */
 	}
@@ -1152,6 +1177,9 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 			}
 	}
 
+	if (c->x86_num_cores > 1)
+		seq_printf(m, "cpu cores\t: %d\n", c->x86_num_cores);
+
 	seq_printf(m, "\n\n"); 
 
 	return 0;
diff --git a/include/asm-x86_64/cpufeature.h b/include/asm-x86_64/cpufeature.h
index 71a401fa3fa5..8a1025f7a2c0 100644
--- a/include/asm-x86_64/cpufeature.h
+++ b/include/asm-x86_64/cpufeature.h
@@ -7,7 +7,7 @@
 #ifndef __ASM_X8664_CPUFEATURE_H
 #define __ASM_X8664_CPUFEATURE_H
 
-#define NCAPINTS	5	/* Currently we have 4 32-bit words worth of info */
+#define NCAPINTS	6
 
 /* Intel-defined CPU features, CPUID level 0x00000001, word 0 */
 #define X86_FEATURE_FPU		(0*32+ 0) /* Onboard FPU */
@@ -72,6 +72,9 @@
 #define X86_FEATURE_CX16	(4*32+13) /* CMPXCHG16B */
 #define X86_FEATURE_XTPR	(4*32+14) /* Send Task Priority Messages */
 
+/* More extended AMD flags: CPUID level 0x80000001, ecx, word 5 */
+#define X86_FEATURE_HTVALID	(5*32+ 0) /* HyperThreading valid, otherwise CMP */
+
 #define cpu_has(c, bit)                test_bit(bit, (c)->x86_capability)
 #define boot_cpu_has(bit)      test_bit(bit, boot_cpu_data.x86_capability)
 
diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
index 68fb42d3a3b3..9495cb914654 100644
--- a/include/asm-x86_64/processor.h
+++ b/include/asm-x86_64/processor.h
@@ -60,6 +60,8 @@ struct cpuinfo_x86 {
 	int	x86_cache_alignment;
 	int	x86_tlbsize;	/* number of 4K pages in DTLB/ITLB combined(in pages)*/
         __u8    x86_virt_bits, x86_phys_bits;
+	__u8	x86_num_cores;
+	__u8	x86_apicid;
         __u32   x86_power; 	
 	unsigned long loops_per_jiffy;
 } ____cacheline_aligned;