linux-kernel - [PATCH v3 01/10] x86/topology: Introduce topology_logical_core

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Date: Mon, 24 Jun 2024 05:58:58 +0000
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<irogers@...gle.com>, <adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
	<tglx@...utronix.de>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <kees@...nel.org>, <gustavoars@...nel.org>,
	<rui.zhang@...el.com>, <oleksandr@...alenko.name>
CC: <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-hardening@...r.kernel.org>, <ananth.narayan@....com>,
	<gautham.shenoy@....com>, <kprateek.nayak@....com>, <ravi.bangoria@....com>,
	<sandipan.das@....com>, <linux-pm@...r.kernel.org>, Dhananjay Ugwekar
	<Dhananjay.Ugwekar@....com>
Subject: [PATCH v3 01/10] x86/topology: Introduce topology_logical_core_id()

From: K Prateek Nayak <kprateek.nayak@....com>

On x86, topology_core_id() returns a unique core ID within the PKG
domain. Looking at match_smt() suggests that a core ID just needs to be
unique within a LLC domain. For use cases such as the per-core RAPL PMU,
there exists a need for a unique core ID across the entire system with
multiple PKG domains. Introduce topology_logical_core_id() to derive a
unique core ID across the system.

Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
---
 Documentation/arch/x86/topology.rst   | 4 ++++
 arch/x86/include/asm/processor.h      | 1 +
 arch/x86/include/asm/topology.h       | 1 +
 arch/x86/kernel/cpu/debugfs.c         | 1 +
 arch/x86/kernel/cpu/topology_common.c | 1 +
 5 files changed, 8 insertions(+)

diff --git a/Documentation/arch/x86/topology.rst b/Documentation/arch/x86/topology.rst
index 7352ab89a55a..c12837e61bda 100644
--- a/Documentation/arch/x86/topology.rst
+++ b/Documentation/arch/x86/topology.rst
@@ -135,6 +135,10 @@ Thread-related topology information in the kernel:
     The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
     "core_id."
 
+  - topology_logical_core_id();
+
+    The logical core ID to which a thread belongs.
+
 
 
 System topology examples
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4fd3364dbc73..e1eeb42edeaf 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -98,6 +98,7 @@ struct cpuinfo_topology {
 	// Logical ID mappings
 	u32			logical_pkg_id;
 	u32			logical_die_id;
+	u32			logical_core_id;
 
 	// AMD Node ID and Nodes per Package info
 	u32			amd_node_id;
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index abe3a8f22cbd..2a6dbf965d92 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -137,6 +137,7 @@ extern const struct cpumask *cpu_clustergroup_mask(int cpu);
 #define topology_logical_package_id(cpu)	(cpu_data(cpu).topo.logical_pkg_id)
 #define topology_physical_package_id(cpu)	(cpu_data(cpu).topo.pkg_id)
 #define topology_logical_die_id(cpu)		(cpu_data(cpu).topo.logical_die_id)
+#define topology_logical_core_id(cpu)		(cpu_data(cpu).topo.logical_core_id)
 #define topology_die_id(cpu)			(cpu_data(cpu).topo.die_id)
 #define topology_core_id(cpu)			(cpu_data(cpu).topo.core_id)
 #define topology_ppin(cpu)			(cpu_data(cpu).ppin)
diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c
index 3baf3e435834..b1eb6d7828db 100644
--- a/arch/x86/kernel/cpu/debugfs.c
+++ b/arch/x86/kernel/cpu/debugfs.c
@@ -24,6 +24,7 @@ static int cpu_debug_show(struct seq_file *m, void *p)
 	seq_printf(m, "core_id:             %u\n", c->topo.core_id);
 	seq_printf(m, "logical_pkg_id:      %u\n", c->topo.logical_pkg_id);
 	seq_printf(m, "logical_die_id:      %u\n", c->topo.logical_die_id);
+	seq_printf(m, "logical_core_id:     %u\n", c->topo.logical_core_id);
 	seq_printf(m, "llc_id:              %u\n", c->topo.llc_id);
 	seq_printf(m, "l2c_id:              %u\n", c->topo.l2c_id);
 	seq_printf(m, "amd_node_id:         %u\n", c->topo.amd_node_id);
diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
index 9a6069e7133c..23722aa21e2f 100644
--- a/arch/x86/kernel/cpu/topology_common.c
+++ b/arch/x86/kernel/cpu/topology_common.c
@@ -151,6 +151,7 @@ static void topo_set_ids(struct topo_scan *tscan, bool early)
 	if (!early) {
 		c->topo.logical_pkg_id = topology_get_logical_id(apicid, TOPO_PKG_DOMAIN);
 		c->topo.logical_die_id = topology_get_logical_id(apicid, TOPO_DIE_DOMAIN);
+		c->topo.logical_core_id = topology_get_logical_id(apicid, TOPO_CORE_DOMAIN);
 	}
 
 	/* Package relative core ID */
-- 
2.34.1