linux-kernel - [tip: sched/urgent] x86/smp: Factor out parts of native_smp_prepare

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Date:   Thu, 11 Nov 2021 12:22:29 -0000
From:   "tip-bot2 for Boris Ostrovsky" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Juergen Gross <jgross@...e.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/urgent] x86/smp: Factor out parts of native_smp_prepare_cpus()

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     ce2612b6706b4d0a70732795253722e3bd4ed953
Gitweb:        https://git.kernel.org/tip/ce2612b6706b4d0a70732795253722e3bd4ed953
Author:        Boris Ostrovsky <boris.ostrovsky@...cle.com>
AuthorDate:    Tue, 02 Nov 2021 19:36:36 -04:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 11 Nov 2021 13:09:32 +01:00

x86/smp: Factor out parts of native_smp_prepare_cpus()

Commit 66558b730f25 ("sched: Add cluster scheduler level for x86")
introduced cpu_l2c_shared_map mask which is expected to be initialized
by smp_op.smp_prepare_cpus(). That commit only updated
native_smp_prepare_cpus() version but not xen_pv_smp_prepare_cpus().
As result Xen PV guests crash in set_cpu_sibling_map().

While the new mask can be allocated in xen_pv_smp_prepare_cpus() one can
see that both versions of smp_prepare_cpus ops share a number of common
operations that can be factored out. So do that instead.

Fixes: 66558b730f25 ("sched: Add cluster scheduler level for x86")
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Juergen Gross <jgross@...e.com>
Link: https://lkml.kernel.org/r/1635896196-18961-1-git-send-email-boris.ostrovsky@oracle.com
---
 arch/x86/include/asm/smp.h |  1 +
 arch/x86/kernel/smpboot.c  | 18 ++++++++++++------
 arch/x86/xen/smp_pv.c      | 12 ++----------
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 08b0e90..81a0211 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -126,6 +126,7 @@ static inline void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 
 void cpu_disable_common(void);
 void native_smp_prepare_boot_cpu(void);
+void smp_prepare_cpus_common(void);
 void native_smp_prepare_cpus(unsigned int max_cpus);
 void calculate_max_logical_packages(void);
 void native_smp_cpus_done(unsigned int max_cpus);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 8241927..ac2909f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1350,12 +1350,7 @@ static void __init smp_get_logical_apicid(void)
 		cpu0_logical_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
 }
 
-/*
- * Prepare for SMP bootup.
- * @max_cpus: configured maximum number of CPUs, It is a legacy parameter
- *            for common interface support.
- */
-void __init native_smp_prepare_cpus(unsigned int max_cpus)
+void __init smp_prepare_cpus_common(void)
 {
 	unsigned int i;
 
@@ -1386,6 +1381,17 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 	set_sched_topology(x86_topology);
 
 	set_cpu_sibling_map(0);
+}
+
+/*
+ * Prepare for SMP bootup.
+ * @max_cpus: configured maximum number of CPUs, It is a legacy parameter
+ *            for common interface support.
+ */
+void __init native_smp_prepare_cpus(unsigned int max_cpus)
+{
+	smp_prepare_cpus_common();
+
 	init_freq_invariance(false, false);
 	smp_sanity_check();
 
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 9e55bcb..6a8f3b5 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -225,7 +225,6 @@ static void __init xen_pv_smp_prepare_boot_cpu(void)
 static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned cpu;
-	unsigned int i;
 
 	if (skip_ioapic_setup) {
 		char *m = (max_cpus == 0) ?
@@ -238,16 +237,9 @@ static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
 	}
 	xen_init_lock_cpu(0);
 
-	smp_store_boot_cpu_info();
-	cpu_data(0).x86_max_cores = 1;
+	smp_prepare_cpus_common();
 
-	for_each_possible_cpu(i) {
-		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
-		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
-		zalloc_cpumask_var(&per_cpu(cpu_die_map, i), GFP_KERNEL);
-		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
-	}
-	set_cpu_sibling_map(0);
+	cpu_data(0).x86_max_cores = 1;
 
 	speculative_store_bypass_ht_init();