x86/cpu: Provide cpu_init/parse_topology()

KAGA-KOKO · KAGA-KOKO · commit ebdb20361059 · 2024-02-15T22:07:36.000+01:00
Topology evaluation is a complete disaster and impenetrable mess. It's scattered all over the place with some vendor implementations doing early evaluation and some not. The most horrific part is the permanent overwriting of smt_max_siblings and __max_die_per_package, instead of establishing them once on the boot CPU and validating the result on the APs. The goals are: - One topology evaluation entry point - Proper sharing of pointlessly duplicated code - Proper structuring of the evaluation logic and preferences. - Evaluating important system wide information only once on the boot CPU - Making the 0xb/0x1f leaf parsing less convoluted and actually fixing the short comings of leaf 0x1f evaluation. Start to consolidate the topology evaluation code by providing the entry points for the early boot CPU evaluation and for the final parsing on the boot CPU and the APs. Move the trivial pieces into that new code: - The initialization of cpuinfo_x86::topo - The evaluation of CPUID leaf 1, which presets topo::initial_apicid - topo_apicid is set to topo::initial_apicid when invoked from early boot. When invoked for the final evaluation on the boot CPU it reads the actual APIC ID, which makes apic_get_initial_apicid() obsolete once everything is converted over. Provide a temporary helper function topo_converted() which shields off the not yet converted CPU vendors from invoking code which would break them. This shielding covers all vendor CPUs which support SMP, but not the historical pure UP ones as they only need the topology info init and eventually the initial APIC initialization. Provide two new members in cpuinfo_x86::topo to store the maximum number of SMT siblings and the number of dies per package and add them to the debugfs readout. These two members will be used to populate this information on the boot CPU and to validate the APs against it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Wang Wendy <wendy.wang@intel.com> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240212153624.581436579@linutronix.de
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
@@ -102,6 +102,25 @@ static inline void setup_node_to_cpumask_map(void) { }
 
 #include <asm-generic/topology.h>
 
+/* Topology information */
+enum x86_topology_domains {
+	TOPO_SMT_DOMAIN,
+	TOPO_CORE_DOMAIN,
+	TOPO_MODULE_DOMAIN,
+	TOPO_TILE_DOMAIN,
+	TOPO_DIE_DOMAIN,
+	TOPO_DIEGRP_DOMAIN,
+	TOPO_PKG_DOMAIN,
+	TOPO_MAX_DOMAIN,
+};
+
+struct x86_topology_system {
+	unsigned int	dom_shifts[TOPO_MAX_DOMAIN];
+	unsigned int	dom_size[TOPO_MAX_DOMAIN];
+};
+
+extern struct x86_topology_system x86_topo_system;
+
 extern const struct cpumask *cpu_coregroup_mask(int cpu);
 extern const struct cpumask *cpu_clustergroup_mask(int cpu);
 
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
@@ -17,7 +17,8 @@ KMSAN_SANITIZE_common.o := n
 # As above, instrumenting secondary CPU boot code causes boot hangs.
 KCSAN_SANITIZE_common.o := n
 
-obj-y			:= cacheinfo.o scattered.o topology.o
+obj-y			:= cacheinfo.o scattered.o
+obj-y			+= topology_common.o topology.o
 obj-y			+= common.o
 obj-y			+= rdrand.o
 obj-y			+= match.o
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
@@ -1591,6 +1591,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		setup_force_cpu_cap(X86_FEATURE_CPUID);
 		cpu_parse_early_param();
 
+		cpu_init_topology(c);
+
 		if (this_cpu->c_early_init)
 			this_cpu->c_early_init(c);
 
@@ -1601,6 +1603,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 			this_cpu->c_bsp_init(c);
 	} else {
 		setup_clear_cpu_cap(X86_FEATURE_CPUID);
+		cpu_init_topology(c);
 	}
 
 	get_cpu_address_sizes(c);
@@ -1748,18 +1751,6 @@ static void generic_identify(struct cpuinfo_x86 *c)
 
 	get_cpu_address_sizes(c);
 
-	if (c->cpuid_level >= 0x00000001) {
-		c->topo.initial_apicid = (cpuid_ebx(1) >> 24) & 0xFF;
-#ifdef CONFIG_X86_32
-# ifdef CONFIG_SMP
-		c->topo.apicid = apic->phys_pkg_id(c->topo.initial_apicid, 0);
-# else
-		c->topo.apicid = c->topo.initial_apicid;
-# endif
-#endif
-		c->topo.pkg_id = c->topo.initial_apicid;
-	}
-
 	get_model_name(c); /* Default name */
 
 	/*
@@ -1818,9 +1809,6 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	c->x86_model_id[0] = '\0';  /* Unset */
 	c->x86_max_cores = 1;
 	c->x86_coreid_bits = 0;
-	c->topo.cu_id = 0xff;
-	c->topo.llc_id = BAD_APICID;
-	c->topo.l2c_id = BAD_APICID;
 #ifdef CONFIG_X86_64
 	c->x86_clflush_size = 64;
 	c->x86_phys_bits = 36;
@@ -1839,17 +1827,19 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 
 	generic_identify(c);
 
+	cpu_parse_topology(c);
+
 	if (this_cpu->c_identify)
 		this_cpu->c_identify(c);
 
 	/* Clear/Set all flags overridden by options, after probe */
 	apply_forced_caps(c);
 
 #ifdef CONFIG_X86_64
-	c->topo.apicid = apic->phys_pkg_id(c->topo.initial_apicid, 0);
+	if (!topo_is_converted(c))
+		c->topo.apicid = apic->phys_pkg_id(c->topo.initial_apicid, 0);
 #endif
 
-
 	/*
 	 * Set default APIC and TSC_DEADLINE MSR fencing flag. AMD and
 	 * Hygon will clear it in ->c_init() below.
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
@@ -2,6 +2,11 @@
 #ifndef ARCH_X86_CPU_H
 #define ARCH_X86_CPU_H
 
+#include <asm/cpu.h>
+#include <asm/topology.h>
+
+#include "topology.h"
+
 /* attempt to consolidate cpu attributes */
 struct cpu_dev {
 	const char	*c_vendor;
@@ -96,4 +101,5 @@ static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode)
 	       mode == SPECTRE_V2_EIBRS_RETPOLINE ||
 	       mode == SPECTRE_V2_EIBRS_LFENCE;
 }
+
 #endif /* ARCH_X86_CPU_H */
diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c
@@ -5,6 +5,8 @@
 #include <asm/apic.h>
 #include <asm/processor.h>
 
+#include "cpu.h"
+
 static int cpu_debug_show(struct seq_file *m, void *p)
 {
 	unsigned long cpu = (unsigned long)m->private;
@@ -42,12 +44,48 @@ static const struct file_operations dfs_cpu_ops = {
 	.release	= single_release,
 };
 
+static int dom_debug_show(struct seq_file *m, void *p)
+{
+	static const char *domain_names[TOPO_MAX_DOMAIN] = {
+		[TOPO_SMT_DOMAIN]	= "Thread",
+		[TOPO_CORE_DOMAIN]	= "Core",
+		[TOPO_MODULE_DOMAIN]	= "Module",
+		[TOPO_TILE_DOMAIN]	= "Tile",
+		[TOPO_DIE_DOMAIN]	= "Die",
+		[TOPO_DIEGRP_DOMAIN]	= "DieGrp",
+		[TOPO_PKG_DOMAIN]	= "Package",
+	};
+	unsigned int dom, nthreads = 1;
+
+	for (dom = 0; dom < TOPO_MAX_DOMAIN; dom++) {
+		nthreads *= x86_topo_system.dom_size[dom];
+		seq_printf(m, "domain: %-10s shift: %u dom_size: %5u max_threads: %5u\n",
+			   domain_names[dom], x86_topo_system.dom_shifts[dom],
+			   x86_topo_system.dom_size[dom], nthreads);
+	}
+	return 0;
+}
+
+static int dom_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, dom_debug_show, inode->i_private);
+}
+
+static const struct file_operations dfs_dom_ops = {
+	.open		= dom_debug_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 static __init int cpu_init_debugfs(void)
 {
 	struct dentry *dir, *base = debugfs_create_dir("topo", arch_debugfs_dir);
 	unsigned long id;
 	char name[24];
 
+	debugfs_create_file("domains", 0444, base, NULL, &dfs_dom_ops);
+
 	dir = debugfs_create_dir("cpus", base);
 	for_each_possible_cpu(id) {
 		sprintf(name, "%lu", id);
diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_X86_TOPOLOGY_H
+#define ARCH_X86_TOPOLOGY_H
+
+struct topo_scan {
+	struct cpuinfo_x86	*c;
+	unsigned int		dom_shifts[TOPO_MAX_DOMAIN];
+	unsigned int		dom_ncpus[TOPO_MAX_DOMAIN];
+};
+
+bool topo_is_converted(struct cpuinfo_x86 *c);
+void cpu_init_topology(struct cpuinfo_x86 *c);
+void cpu_parse_topology(struct cpuinfo_x86 *c);
+void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom,
+		      unsigned int shift, unsigned int ncpus);
+
+static inline u32 topo_shift_apicid(u32 apicid, enum x86_topology_domains dom)
+{
+	if (dom == TOPO_SMT_DOMAIN)
+		return apicid;
+	return apicid >> x86_topo_system.dom_shifts[dom - 1];
+}
+
+static inline u32 topo_relative_domain_id(u32 apicid, enum x86_topology_domains dom)
+{
+	if (dom != TOPO_SMT_DOMAIN)
+		apicid >>= x86_topo_system.dom_shifts[dom - 1];
+	return apicid & (x86_topo_system.dom_size[dom] - 1);
+}
+
+static inline u32 topo_domain_mask(enum x86_topology_domains dom)
+{
+	return (1U << x86_topo_system.dom_shifts[dom]) - 1;
+}
+
+#endif /* ARCH_X86_TOPOLOGY_H */
diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
