Re: [PATCH 1/3] x86, amd: Store number of nodes in a static global variable

[Borislav Petkov]

On Tue, Jun 09, 2015 at 11:45:15AM -0500, Aravind Gopalakrishnan wrote:
> Moving this out of function local scope as we want to
> allow EDAC to be able to view this topology attribute.
> 
> A follow-up patch introduces an accessor function for this variable
> that will be used by EDAC's mce_amd_inj module.
> 
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Jacob Shin <jacob.w.shin@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
> ---
>  arch/x86/kernel/cpu/amd.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)

I did some cleanup and merged it with the next patch. It seems simple
enough and splitting it was not such a good idea, after all. And called
it nodes_per_socket to avoid confusion.

---
From: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
Date: Tue, 9 Jun 2015 11:45:15 -0500
Subject: [PATCH] x86/cpu/amd: Give access to the number of nodes in a physical
 package

Stash the number of nodes in a physical processor package locally and
add an accessor to be called by interested parties. The first user is
the MCE injection module which uses it to find the node base core in a
package for injecting a certain type of errors.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jacob Shin <jacob.w.shin@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Cc: mchehab@xxxxxxxxxxxxxxx
Cc: x86-ml <x86@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1433868317-18417-2-git-send-email-Aravind.Gopalakrishnan@xxxxxxx
[ Rewrite commit message, merge with the accessor patch and unify naming. ]
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/include/asm/processor.h |  1 +
 arch/x86/kernel/cpu/amd.c        | 23 ++++++++++++++++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 23ba6765b718..9aa52fd13a78 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -946,6 +946,7 @@ static inline int mpx_disable_management(struct task_struct *tsk)
 #endif /* CONFIG_X86_INTEL_MPX */
 
 extern u16 amd_get_nb_id(int cpu);
+extern u32 amd_get_nodes_per_socket(void);
 
 static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
 {
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 94e7051fba1a..56cae1964a81 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -19,6 +19,13 @@
 
 #include "cpu.h"
 
+/*
+ * nodes_per_socket: Stores the number of nodes per socket.
+ * Refer to Fam15h Models 00-0fh BKDG - CPUID Fn8000_001E_ECX
+ * Node Identifiers[10:8]
+ */
+static u32 nodes_per_socket = 1;
+
 static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
 {
 	u32 gprs[8] = { 0 };
@@ -291,7 +298,7 @@ static int nearby_node(int apicid)
 #ifdef CONFIG_X86_HT
 static void amd_get_topology(struct cpuinfo_x86 *c)
 {
-	u32 nodes, cores_per_cu = 1;
+	u32 cores_per_cu = 1;
 	u8 node_id;
 	int cpu = smp_processor_id();
 
@@ -300,7 +307,7 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
 		u32 eax, ebx, ecx, edx;
 
 		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
-		nodes = ((ecx >> 8) & 7) + 1;
+		nodes_per_socket = ((ecx >> 8) & 7) + 1;
 		node_id = ecx & 7;
 
 		/* get compute unit information */
@@ -311,18 +318,18 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
 		u64 value;
 
 		rdmsrl(MSR_FAM10H_NODE_ID, value);
-		nodes = ((value >> 3) & 7) + 1;
+		nodes_per_socket = ((value >> 3) & 7) + 1;
 		node_id = value & 7;
 	} else
 		return;
 
 	/* fixup multi-node processor information */
-	if (nodes > 1) {
+	if (nodes_per_socket > 1) {
 		u32 cores_per_node;
 		u32 cus_per_node;
 
 		set_cpu_cap(c, X86_FEATURE_AMD_DCM);
-		cores_per_node = c->x86_max_cores / nodes;
+		cores_per_node = c->x86_max_cores / nodes_per_socket;
 		cus_per_node = cores_per_node / cores_per_cu;
 
 		/* store NodeID, use llc_shared_map to store sibling info */
@@ -366,6 +373,12 @@ u16 amd_get_nb_id(int cpu)
 }
 EXPORT_SYMBOL_GPL(amd_get_nb_id);
 
+u32 amd_get_nodes_per_socket(void)
+{
+	return nodes_per_socket;
+}
+EXPORT_SYMBOL_GPL(amd_get_nodes_per_socket);
+
 static void srat_detect_node(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_NUMA
-- 
2.3.5

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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