From: Usama Arif <usama.arif@bytedance.com>
To: David Woodhouse <dwmw2@infradead.org>,
Oleksandr Natalenko <oleksandr@natalenko.name>,
tglx@linutronix.de, kim.phillips@amd.com, brgerst@gmail.com
Cc: piotrgorski@cachyos.org, arjan@linux.intel.com, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com,
thomas.lendacky@amd.com, seanjc@google.com,
pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
punit.agrawal@bytedance.com, simon.evans@bytedance.com,
liangma@liangbit.com
Subject: Re: [External] Re: [PATCH v12 00/11] Parallel CPU bringup for x86_64
Date: Mon, 27 Feb 2023 16:32:50 +0000 [thread overview]
Message-ID: <0f4dc622-6273-8abc-bf9a-d4f737ccb8e9@bytedance.com> (raw)
In-Reply-To: <90c7efe278fed0616275ed64215ec1fe249f16f5.camel@infradead.org>
On 27/02/2023 15:29, David Woodhouse wrote:
> On Mon, 2023-02-27 at 06:14 +0000, Usama Arif wrote:
>>
>> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
>> index 17bdd6122dca..5d709aa67df4 100644
>> --- a/arch/x86/kernel/head_64.S
>> +++ b/arch/x86/kernel/head_64.S
>> @@ -273,7 +273,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify,
>> SYM_L_GLOBAL)
>> cmpl (%rbx,%rcx,4), %edx
>> jz .Lsetup_cpu
>> inc %ecx
>> +#if (NR_CPUS == 1) || defined(CONFIG_FORCE_NR_CPUS)
>> + cmpl $NR_CPUS, %ecx
>> +#else
>> cmpl nr_cpu_ids(%rip), %ecx
>> +#endif
>> jb .Lfind_cpunr
>>
>> /* APIC ID not found in the table. Drop the trampoline lock
>> and bail. */
>
> The whitespace looks dodgy there but maybe that's just your mail client?
>
> Given this code is already in #ifdef CONFIG_SMP, can NR_CPUS be 1?
Ah yes, we have
config NR_CPUS_RANGE_BEGIN
int
default NR_CPUS_RANGE_END if MAXSMP
default 1 if !SMP
default 2
in arch/x86/Kconfig which doesn't let us select 1 for NR_CPUS if SMP is
enabled, so this should be enough
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 17bdd6122dca..c79ae67492e1 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -273,7 +273,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify,
SYM_L_GLOBAL)
cmpl (%rbx,%rcx,4), %edx
jz .Lsetup_cpu
inc %ecx
+#if defined(CONFIG_FORCE_NR_CPUS)
+ cmpl $NR_CPUS, %ebx
+#else
cmpl nr_cpu_ids(%rip), %ecx
+#endif
jb .Lfind_cpunr
next prev parent reply other threads:[~2023-02-27 16:33 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-26 11:07 Usama Arif
2023-02-26 11:07 ` [PATCH v12 01/11] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Usama Arif
2023-02-26 11:07 ` [PATCH v12 02/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-02-26 11:07 ` [PATCH v12 03/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-02-26 11:07 ` [PATCH v12 04/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-02-26 11:07 ` [PATCH v12 05/11] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-02-26 11:07 ` [PATCH v12 06/11] x86/smpboot: Remove initial_stack on 64-bit Usama Arif
2023-02-28 16:13 ` Thomas Gleixner
2023-02-28 16:25 ` David Woodhouse
2023-02-28 20:32 ` Thomas Gleixner
2023-02-28 17:09 ` David Woodhouse
2023-02-28 20:17 ` Thomas Gleixner
2023-02-28 20:43 ` David Woodhouse
2023-03-01 10:18 ` Thomas Gleixner
2023-03-01 10:42 ` David Woodhouse
2023-02-28 22:22 ` Brian Gerst
2023-02-26 11:07 ` [PATCH v12 07/11] x86/smpboot: Remove early_gdt_descr " Usama Arif
2023-02-28 21:01 ` Thomas Gleixner
2023-02-28 21:02 ` Arjan van de Ven
2023-03-01 20:32 ` Josh Triplett
2023-03-01 22:16 ` Paul E. McKenney
2023-03-01 22:25 ` Josh Triplett
2023-03-02 0:28 ` Paul E. McKenney
2023-03-02 1:05 ` Randy Dunlap
2023-03-02 1:37 ` Paul E. McKenney
2023-02-28 21:57 ` David Woodhouse
2023-02-28 22:41 ` David Woodhouse
2023-02-28 22:48 ` Brian Gerst
2023-02-28 23:42 ` David Woodhouse
2023-03-01 0:02 ` H. Peter Anvin
2023-03-01 7:39 ` David Woodhouse
2023-03-01 0:03 ` Brian Gerst
2023-03-01 10:27 ` Thomas Gleixner
2023-02-28 22:09 ` Brian Gerst
2023-02-26 11:07 ` [PATCH v12 08/11] x86/smpboot: Remove initial_gs Usama Arif
2023-02-26 11:08 ` [PATCH v12 09/11] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-02-26 11:08 ` [PATCH v12 10/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-02-26 11:08 ` [PATCH v12 11/11] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-02-26 18:31 ` [PATCH v12 00/11] Parallel CPU bringup for x86_64 Oleksandr Natalenko
2023-02-26 20:59 ` [External] " Usama Arif
2023-02-27 6:13 ` David Woodhouse
2023-02-27 6:25 ` Usama Arif
2023-02-27 6:14 ` Usama Arif
2023-02-27 15:29 ` David Woodhouse
2023-02-27 16:32 ` Usama Arif [this message]
2023-02-27 21:39 ` Guilherme G. Piccoli
2023-02-28 9:07 ` David Woodhouse
2023-02-28 10:13 ` Paul Menzel
2023-02-28 12:04 ` Guilherme G. Piccoli
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