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Piccoli" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230512205256.206394064@linutronix.de> References: <20230512205256.206394064@linutronix.de> MIME-Version: 1.0 Message-ID: <168422819999.404.14981768167213672785.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1765724842956842089?= X-GMAIL-MSGID: =?utf-8?q?1766042138474846277?= The following commit has been merged into the smp/core branch of tip: Commit-ID: c8b7fb09d1bcfa61d4211f61542e1291e7b4cbad Gitweb: https://git.kernel.org/tip/c8b7fb09d1bcfa61d4211f61542e1291e7b4cbad Author: Thomas Gleixner AuthorDate: Fri, 12 May 2023 23:07:19 +02:00 Committer: Peter Zijlstra CommitterDate: Mon, 15 May 2023 13:44:53 +02:00 x86/smpboot: Remove cpu_callin_mask Now that TSC synchronization is SMP function call based there is no reason to wait for the AP to be set in smp_callin_mask. The control CPU waits for the AP to set itself in the online mask anyway. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Tested-by: Michael Kelley Tested-by: Oleksandr Natalenko Tested-by: Helge Deller # parisc Tested-by: Guilherme G. Piccoli # Steam Deck Link: https://lore.kernel.org/r/20230512205256.206394064@linutronix.de --- arch/x86/kernel/smpboot.c | 74 +++++++------------------------------- 1 file changed, 15 insertions(+), 59 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index b2f44a8..3f731be 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -104,7 +104,6 @@ EXPORT_PER_CPU_SYMBOL(cpu_info); /* All of these masks are initialized in setup_cpu_local_masks() */ static cpumask_var_t cpu_initialized_mask; static cpumask_var_t cpu_callout_mask; -static cpumask_var_t cpu_callin_mask; /* Representing CPUs for which sibling maps can be computed */ static cpumask_var_t cpu_sibling_setup_mask; @@ -161,38 +160,30 @@ static inline void smpboot_restore_warm_reset_vector(void) } -/* - * Report back to the Boot Processor during boot time or to the caller processor - * during CPU online. - */ -static void smp_callin(void) +/* Run the next set of setup steps for the upcoming CPU */ +static void ap_starting(void) { - int cpuid; - - /* - * If waken up by an INIT in an 82489DX configuration - * cpu_callout_mask guarantees we don't get here before - * an INIT_deassert IPI reaches our local APIC, so it is - * now safe to touch our local APIC. - */ - cpuid = smp_processor_id(); + int cpuid = smp_processor_id(); /* - * the boot CPU has finished the init stage and is spinning - * on callin_map until we finish. We are free to set up this - * CPU, first the APIC. (this is probably redundant on most - * boards) + * If woken up by an INIT in an 82489DX configuration + * cpu_callout_mask guarantees the CPU does not reach this point + * before an INIT_deassert IPI reaches the local APIC, so it is now + * safe to touch the local APIC. + * + * Set up this CPU, first the APIC, which is probably redundant on + * most boards. */ apic_ap_setup(); - /* Save our processor parameters. */ + /* Save the processor parameters. */ smp_store_cpu_info(cpuid); /* * The topology information must be up to date before * notify_cpu_starting(). */ - set_cpu_sibling_map(raw_smp_processor_id()); + set_cpu_sibling_map(cpuid); ap_init_aperfmperf(); @@ -205,11 +196,6 @@ static void smp_callin(void) * state CPUHP_ONLINE. */ notify_cpu_starting(cpuid); - - /* - * Allow the master to continue. - */ - cpumask_set_cpu(cpuid, cpu_callin_mask); } static void ap_calibrate_delay(void) @@ -268,12 +254,7 @@ static void notrace start_secondary(void *unused) rcu_cpu_starting(raw_smp_processor_id()); x86_cpuinit.early_percpu_clock_init(); - /* - * Sync point with wait_cpu_callin(). The AP doesn't wait here - * but just sets the bit to let the controlling CPU (BSP) know that - * it's got this far. - */ - smp_callin(); + ap_starting(); /* Check TSC synchronization with the control CPU. */ check_tsc_sync_target(); @@ -1109,7 +1090,7 @@ static int wait_cpu_cpumask(unsigned int cpu, const struct cpumask *mask) * and thus wait_for_master_cpu(), then set cpu_callout_mask to allow it * to proceed. The AP will then proceed past setting its 'callin' bit * and end up waiting in check_tsc_sync_target() until we reach - * do_wait_cpu_online() to tend to it. + * wait_cpu_online() to tend to it. */ static int wait_cpu_initialized(unsigned int cpu) { @@ -1124,20 +1105,7 @@ static int wait_cpu_initialized(unsigned int cpu) } /* - * Bringup step three: Wait for the target AP to reach smp_callin(). - * The AP is not waiting for us here so we don't need to parallelise - * this step. Not entirely clear why we care about this, since we just - * proceed directly to TSC synchronization which is the next sync - * point with the AP anyway. - */ -static void wait_cpu_callin(unsigned int cpu) -{ - while (!cpumask_test_cpu(cpu, cpu_callin_mask)) - schedule(); -} - -/* - * Bringup step four: Wait for the target AP to reach set_cpu_online() in + * Bringup step three: Wait for the target AP to reach set_cpu_online() in * start_secondary(). */ static void wait_cpu_online(unsigned int cpu) @@ -1167,14 +1135,6 @@ static int native_kick_ap(unsigned int cpu, struct task_struct *tidle) } /* - * Already booted CPU? - */ - if (cpumask_test_cpu(cpu, cpu_callin_mask)) { - pr_debug("do_boot_cpu %d Already started\n", cpu); - return -ENOSYS; - } - - /* * Save current MTRR state in case it was changed since early boot * (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync: */ @@ -1211,7 +1171,6 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) if (ret) goto out; - wait_cpu_callin(cpu); wait_cpu_online(cpu); out: @@ -1327,7 +1286,6 @@ void __init smp_prepare_cpus_common(void) * Setup boot CPU information */ smp_store_boot_cpu_info(); /* Final full version of the data */ - cpumask_copy(cpu_callin_mask, cpumask_of(0)); mb(); for_each_possible_cpu(i) { @@ -1542,7 +1500,6 @@ __init void prefill_possible_map(void) void __init setup_cpu_local_masks(void) { alloc_bootmem_cpumask_var(&cpu_initialized_mask); - alloc_bootmem_cpumask_var(&cpu_callin_mask); alloc_bootmem_cpumask_var(&cpu_callout_mask); alloc_bootmem_cpumask_var(&cpu_sibling_setup_mask); } @@ -1606,7 +1563,6 @@ static void remove_cpu_from_maps(int cpu) { set_cpu_online(cpu, false); cpumask_clear_cpu(cpu, cpu_callout_mask); - cpumask_clear_cpu(cpu, cpu_callin_mask); /* was set by cpu_init() */ cpumask_clear_cpu(cpu, cpu_initialized_mask); numa_remove_cpu(cpu);