x86/cpu: Provide cpu_init/parse_topology()

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

1 files changed, 7 insertions, 17 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0b97bcde70c6..d674e7bdd6e4 100644
--- 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;
@@ -1839,6 +1827,8 @@ 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);
 
@@ -1846,10 +1836,10 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	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.