From: Thomas Gleixner <tglx@linutronix.de>
To: Usama Arif <usama.arif@bytedance.com>,
dwmw2@infradead.org, arjan@linux.intel.com
Cc: 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,
Usama Arif <usama.arif@bytedance.com>
Subject: Re: [PATCH v6 06/11] x86/smpboot: Support parallel startup of secondary CPUs
Date: Tue, 07 Feb 2023 01:07:45 +0100 [thread overview]
Message-ID: <87v8kewd66.ffs@tglx> (raw)
In-Reply-To: <20230202215625.3248306-7-usama.arif@bytedance.com>
On Thu, Feb 02 2023 at 21:56, Usama Arif wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> To allow for parallel AP bringup, we need to avoid the use of global
> variables for passing information to the APs, as well as preventing them
> from all trying to use the same real-mode stack simultaneously.
>
> So, introduce a 'lock' field in struct trampoline_header to use as a
> simple bit-spinlock for the real-mode stack. That lock also protects
> the global variables initial_gs, initial_stack and early_gdt_descr,
> which can now be calculated...
>
> So how do we calculate those addresses? Well, they they can all be found
> from the per_cpu data for this CPU. Simples! Except... how does it know
> what its CPU# is? OK, we export the cpuid_to_apicid[] array and it can
> search it to find its APIC ID in there.
>
> But now you whine at me that it doesn't even know its APIC ID? Well, if
> it's a relatively modern CPU then the APIC ID is in CPUID leaf 0x0B so
> we can use that. Otherwise... erm... OK, otherwise it can't have parallel
> CPU bringup for now. We'll still use a global variable for those CPUs and
> bring them up one at a time.
>
> So add a global 'smpboot_control' field which either contains the APIC
> ID, or a flag indicating that it can be found in CPUID.
>
> This adds the 'do_parallel_bringup' flag in preparation but doesn't
> actually enable parallel bringup yet.
>
> [ dwmw2: Minor tweaks, write a commit message ]
> [ seanc: Fix stray override of initial_gs in common_cpu_up() ]
> Not-signed-off-by: Thomas Gleixner <tglx@linutronix.de>
I'm happy to add my SOB if someone actually writes a coherent changelog
which complies with the documented rules :)
next prev parent reply other threads:[~2023-02-07 0:07 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 21:56 [PATCH v6 00/11] Parallel CPU bringup for x86_64 Usama Arif
2023-02-02 21:56 ` [PATCH v6 01/11] x86/apic/x2apic: Fix parallel handling of cluster_mask Usama Arif
2023-02-06 23:20 ` Thomas Gleixner
2023-02-07 10:57 ` David Woodhouse
2023-02-07 11:27 ` David Woodhouse
2023-02-07 14:24 ` Thomas Gleixner
2023-02-07 19:53 ` David Woodhouse
2023-02-07 20:58 ` Thomas Gleixner
2023-02-07 14:22 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 02/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-02-06 23:33 ` Thomas Gleixner
2023-02-07 1:24 ` Paul E. McKenney
2023-02-02 21:56 ` [PATCH v6 03/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-02-06 23:43 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 04/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-02-06 23:48 ` Thomas Gleixner
[not found] ` <57195f701f6d1d70ec440c9a28cbee4cfb81dc41.camel@amazon.co.uk>
2023-02-07 14:39 ` Thomas Gleixner
2023-02-07 16:50 ` Sean Christopherson
2023-02-07 19:48 ` [EXTERNAL][PATCH " David Woodhouse
2023-02-02 21:56 ` [PATCH v6 05/11] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-02-06 23:59 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 06/11] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-02-02 22:30 ` David Woodhouse
2023-02-02 22:50 ` [External] " Usama Arif
2023-02-03 8:14 ` David Woodhouse
2023-02-03 14:41 ` Arjan van de Ven
2023-02-03 18:17 ` Sean Christopherson
2023-02-07 0:07 ` Thomas Gleixner [this message]
2023-02-02 21:56 ` [PATCH v6 07/11] x86/smpboot: Disable parallel boot for AMD CPUs Usama Arif
2023-02-03 19:48 ` Kim Phillips
[not found] ` <d5ec64236ba75f0d3f3718fb69b2cb9169d8af0a.camel@amazon.co.uk>
2023-02-03 21:45 ` Kim Phillips
2023-02-03 22:25 ` [EXTERNAL][PATCH " David Woodhouse
2023-02-04 9:07 ` [PATCH " David Woodhouse
2023-02-04 10:09 ` David Woodhouse
2023-02-04 15:40 ` David Woodhouse
2023-02-04 18:18 ` Arjan van de Ven
2023-02-04 22:31 ` David Woodhouse
2023-02-05 22:13 ` [External] " Usama Arif
2023-02-06 8:05 ` David Woodhouse
2023-02-06 12:11 ` Usama Arif
2023-02-06 18:07 ` Sean Christopherson
2023-02-06 17:58 ` Kim Phillips
2023-02-07 16:27 ` Kim Phillips
2023-02-07 0:23 ` Thomas Gleixner
2023-02-07 10:04 ` David Woodhouse
2023-02-07 14:44 ` Thomas Gleixner
2023-02-07 0:09 ` Thomas Gleixner
[not found] ` <cbd9e88e738dc0c479e87121ca82431731905c73.camel@amazon.co.uk>
2023-02-07 14:46 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 08/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-02-07 0:28 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 09/11] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup Usama Arif
2023-02-02 21:56 ` [PATCH v6 10/11] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-02-02 21:56 ` [PATCH v6 11/11] x86/smpboot: reuse timer calibration Usama Arif
2023-02-07 0:31 ` Thomas Gleixner
2023-02-07 23:16 ` Arjan van de Ven
2023-02-07 23:55 ` Thomas Gleixner
2023-02-05 19:17 ` [PATCH v6 00/11] Parallel CPU bringup for x86_64 Russ Anderson
2023-02-06 8:28 ` David Woodhouse
2023-02-06 12:18 ` [External] " Usama Arif
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