[PATCH 2/3] x86: add topology detection for AMD multi-node processors

[Andreas Herrmann <andreas.herrmann3@amd.com>]

This adapts CPU topology detection for AMD Magny-Cours.

Here is example output from two cores on same package but different
internal cpu_nodes:

/sys/devices/system/cpu/cpu5:
  physical_package_id        : 0
  core_id                    : 5
  thread_siblings            : 00000020
  thread_siblings_list       : 5
  cpu_node_id                : 0
  cpu_node_siblings          : 0000003f
  cpu_node_siblings_list     : 0-5
  core_siblings              : 00000fff
  core_siblings_list         : 0-11
/sys/devices/system/cpu/cpu6:
  physical_package_id        : 0
  core_id                    : 0
  thread_siblings            : 00000040
  thread_siblings_list       : 6
  cpu_node_id                : 1
  cpu_node_siblings          : 00000fc0
  cpu_node_siblings_list     : 6-11
  core_siblings              : 00000fff
  core_siblings_list         : 0-11

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
---
 arch/x86/include/asm/cpufeature.h |    1 +
 arch/x86/kernel/cpu/amd.c         |   63 +++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 13cc6a5..7abe596 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -94,6 +94,7 @@
 #define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be reliable */
 #define X86_FEATURE_NONSTOP_TSC	(3*32+24) /* TSC does not stop in C states */
 #define X86_FEATURE_CLFLUSH_MONITOR (3*32+25) /* "" clflush reqd with monitor */
+#define X86_FEATURE_AMD_DCM     (3*32+26) /* multi-node processor */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* "pni" SSE-3 */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 728b375..53ac4b5 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -6,6 +6,7 @@
 #include <asm/processor.h>
 #include <asm/apic.h>
 #include <asm/cpu.h>
+#include <asm/pci-direct.h>
 
 #ifdef CONFIG_X86_64
 # include <asm/numa_64.h>
@@ -250,6 +251,58 @@ static int __cpuinit nearby_node(int apicid)
 #endif
 
 /*
+ * Fixup core topology information for AMD multi-node processors.
+ * Assumption 1: Number of cores in each internal node is the same.
+ * Assumption 2: Mixed systems with both single-node and dual-node
+ *               processors are not supported.
+ */
+static void __cpuinit amd_fixup_dcm(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_MULTI_NODE_CPU
+	u32 t, cpn;
+	u8 n;
+
+	/* fixup topology information only once for a core */
+	if (cpu_has(c, X86_FEATURE_AMD_DCM))
+		return;
+
+	/* check for multi-node processor on boot cpu */
+	t = read_pci_config(0, 24, 3, 0xe8);
+	if (!(t & (1 << 29)))
+		return;
+
+	set_cpu_cap(c, X86_FEATURE_AMD_DCM);
+
+	/* cores per node: each internal node has half the number of cores */
+	cpn = c->x86_max_cores >> 1;
+
+	/* even-numbered NB_id of this dual-node processor */
+	n = c->phys_proc_id << 1;
+
+	/*
+	 * determine internal node id and assign cores fifty-fifty to
+	 * each node of the dual-node processor
+	 */
+	t = read_pci_config(0, 24 + n, 3, 0xe8);
+	n = (t>>30) & 0x3;
+	if (n == 0) {
+		if (c->cpu_core_id < cpn)
+			c->cpu_node_id = 0;
+		else
+			c->cpu_node_id = 1;
+	} else {
+		if (c->cpu_core_id < cpn)
+			c->cpu_node_id = 1;
+		else
+			c->cpu_node_id = 0;
+	}
+
+	 /* fixup core id to be in range from 0 to cpn */
+	c->cpu_core_id = c->cpu_core_id % cpn;
+#endif
+}
+
+/*
  * 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.
  */
@@ -264,6 +317,9 @@ static void __cpuinit amd_detect_cmp(struct cpuinfo_x86 *c)
 	c->cpu_core_id = c->initial_apicid & ((1 << bits)-1);
 	/* Convert the initial APIC ID into the socket ID */
 	c->phys_proc_id = c->initial_apicid >> bits;
+	/* fixup topology information on multi-node processors */
+	if ((c->x86 == 0x10) && (c->x86_model == 9))
+		amd_fixup_dcm(c);
 #endif
 }
 
@@ -274,7 +330,14 @@ static void __cpuinit srat_detect_node(struct cpuinfo_x86 *c)
 	int node;
 	unsigned apicid = cpu_has_apic ? hard_smp_processor_id() : c->apicid;
 
+#ifdef CONFIG_MULTI_NODE_CPU
+	if (cpu_has(c, X86_FEATURE_AMD_DCM))
+		node = (c->phys_proc_id << 1) + c->cpu_node_id;
+	else
+		node = c->phys_proc_id;
+#else
 	node = c->phys_proc_id;
+#endif
 	if (apicid_to_node[apicid] != NUMA_NO_NODE)
 		node = apicid_to_node[apicid];
 	if (!node_online(node)) {
-- 
1.6.3.1