linux-kernel - [PATCH 2/2] x86/CPU/AMD: Derive CPU topology from CPUID Fn0xB

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Message-Id: <1522051559-23415-3-git-send-email-suravee.suthikulpanit@amd.com>
Date:   Mon, 26 Mar 2018 03:05:59 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, bp@...e.de,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH 2/2] x86/CPU/AMD: Derive CPU topology from CPUID Fn0xB

Derive topology information from Extended Topology Enumeration
(CPUID Fn0x0000000B) when the information is available.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kernel/cpu/amd.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 2c1a9f2..2b40144 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -338,10 +338,18 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
 			c->cu_id = ebx & 0xff;
 
 		if (c->x86 >= 0x17) {
-			c->cpu_core_id = ebx & 0xff;
+			int err = detect_extended_topology(c);
 
-			if (smp_num_siblings > 1)
-				c->x86_max_cores /= smp_num_siblings;
+			if (err) {
+				c->cpu_core_id = ebx & 0xff;
+
+				if (smp_num_siblings > 1)
+					c->x86_max_cores /= smp_num_siblings;
+			} else {
+				int bits = get_count_order(c->x86_max_cores);
+
+				c->x86_coreid_bits = get_count_order(bits);
+			}
 		}
 
 		cacheinfo_amd_init_llc_id(c, cpu, node_id);
@@ -378,7 +386,6 @@ static void amd_detect_cmp(struct cpuinfo_x86 *c)
 	c->phys_proc_id = c->initial_apicid >> bits;
 	/* use socket ID also for last level cache */
 	per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
-	amd_get_topology(c);
 }
 
 u16 amd_get_nb_id(int cpu)
@@ -823,6 +830,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	/* Multi core CPU? */
 	if (c->extended_cpuid_level >= 0x80000008) {
 		amd_detect_cmp(c);
+		amd_get_topology(c);
 		srat_detect_node(c);
 	}
 
-- 
2.7.4