linux-kernel - [patch 44/53] x86/cpu/topology: Mop up primary thread mask handling

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Message-ID: <20230807135028.747059118@linutronix.de>
Date:   Mon,  7 Aug 2023 15:53:42 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Tom Lendacky <thomas.lendacky@....com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Huang Rui <ray.huang@....com>, Juergen Gross <jgross@...e.com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Zhang Rui <rui.zhang@...el.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Feng Tang <feng.tang@...el.com>,
        Andy Shevchenko <andy@...radead.org>
Subject: [patch 44/53] x86/cpu/topology: Mop up primary thread mask handling

The early initcall to initialize the primary thread mask is not longer
required because topology_init_possible_cpus() can mark primary threads
correctly when initializing the possible and present map as the number of
SMT threads is already determined correctly.

The XENPV workaround is not longer required because XENPV now registers
fake APIC IDs which will just work like any other enumeration.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/cpu/topology.c |   29 ++---------------------------
 1 file changed, 2 insertions(+), 27 deletions(-)

--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -92,30 +92,6 @@ static void cpu_mark_primary_thread(unsi
 	if (smp_num_siblings == 1 || !(apicid & mask))
 		cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
 }
-
-/*
- * Due to the utter mess of CPUID evaluation smp_num_siblings is not valid
- * during early boot. Initialize the primary thread mask before SMP
- * bringup.
- */
-static int __init smp_init_primary_thread_mask(void)
-{
-	unsigned int cpu;
-
-	/*
-	 * XEN/PV provides either none or useless topology information.
-	 * Pretend that all vCPUs are primary threads.
-	 */
-	if (xen_pv_domain()) {
-		cpumask_copy(&__cpu_primary_thread_mask, cpu_possible_mask);
-		return 0;
-	}
-
-	for (cpu = 0; cpu < topo_info.nr_assigned_cpus; cpu++)
-		cpu_mark_primary_thread(cpu, cpuid_to_apicid[cpu]);
-	return 0;
-}
-early_initcall(smp_init_primary_thread_mask);
 #else
 static inline void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid) { }
 #endif
@@ -161,9 +137,6 @@ static void topo_set_cpuids(unsigned int
 #endif
 	set_cpu_possible(cpu, true);
 	set_cpu_present(cpu, true);
-
-	if (system_state != SYSTEM_BOOTING)
-		cpu_mark_primary_thread(cpu, apic_id);
 }
 
 /**
@@ -252,6 +225,7 @@ int topology_hotplug_apic(u32 apic_id, u
 
 	set_bit(apic_id, phys_cpu_present_map);
 	topo_set_cpuids(cpu, apic_id, acpi_id);
+	cpu_mark_primary_thread(cpu, apic_id);
 	return cpu;
 }
 
@@ -422,6 +396,7 @@ void __init topology_init_possible_cpus(
 		if (apicid == BAD_APICID)
 			continue;
 
+		cpu_mark_primary_thread(cpu, apicid);
 		set_cpu_present(cpu, test_bit(apicid, phys_cpu_present_map));
 	}
 }