From: Borislav Petkov <bp@alien8.de>
To: Usama Arif <usama.arif@bytedance.com>
Cc: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com,
brgerst@gmail.com, piotrgorski@cachyos.org,
oleksandr@natalenko.name, arjan@linux.intel.com,
mingo@redhat.com, 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, gpiccoli@igalia.com,
David Woodhouse <dwmw@amazon.co.uk>
Subject: Re: [PATCH v15 02/12] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h>
Date: Sun, 19 Mar 2023 17:34:09 +0100 [thread overview]
Message-ID: <20230319163409.GBZBc5gTU94IdrucNL@fat_crate.local> (raw)
In-Reply-To: <20230316222109.1940300-3-usama.arif@bytedance.com>
On Thu, Mar 16, 2023 at 10:20:59PM +0000, Usama Arif wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
>
> Instead of relying purely on the special-case wrapper in bringup_cpu()
> to pass the idle thread to __cpu_up(), expose idle_thread_get() so that
> the architecture code can obtain it directly when necessary.
>
> This will be useful when the existing __cpu_up() is split into multiple
> phases, only *one* of which will actually need the idle thread.
>
> If the architecture code is to register its new pre-bringup states with
> the cpuhp core, having a special-case wrapper to pass extra arguments is
> non-trivial and it's easier just to let the arch register its function
> pointer to be invoked with the standard API.
>
> To reduce duplication, move the shadow stack reset and kasan unpoisoning
I was wondering what "shadow stack" as that set is not upstream yet. You mean
"shadow call stack" which is apparently something else,
compiler-generated, purely software thing.
> into idle_thread_get() too.
Frankly, I don't think resetting shadow call stack and kasan state
belongs in a function which returns the idle thread. Even more so if you
have to add an @unpoison param which is false sometimes and sometimes
true, depending on where you call the function.
I think you should have a helper
tsk_reset_stacks(struct task_struct *tsk);
or so which is called where @unpoison == true instead of having a getter
function do something unrelated too.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-03-19 16:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-16 22:20 [PATCH v15 00/12] Parallel CPU bringup for x86_64 Usama Arif
2023-03-16 22:20 ` [PATCH v15 01/12] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Usama Arif
2023-03-21 14:14 ` [tip: x86/apic] " tip-bot2 for David Woodhouse
2023-03-16 22:20 ` [PATCH v15 02/12] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-03-19 16:34 ` Borislav Petkov [this message]
2023-03-20 8:17 ` David Woodhouse
2023-03-21 19:20 ` David Woodhouse
2023-03-16 22:21 ` [PATCH v15 03/12] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-03-20 14:30 ` Thomas Gleixner
2023-03-21 19:14 ` David Woodhouse
2023-03-16 22:21 ` [PATCH v15 04/12] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-03-21 11:41 ` Borislav Petkov
2023-03-21 11:43 ` David Woodhouse
2023-03-21 14:14 ` [tip: x86/apic] " tip-bot2 for David Woodhouse
2023-03-16 22:21 ` [PATCH v15 05/12] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-03-16 22:21 ` [PATCH v15 06/12] x86/smpboot: Remove initial_stack on 64-bit Usama Arif
2023-03-21 14:14 ` [tip: x86/apic] " tip-bot2 for Brian Gerst
2023-03-16 22:21 ` [PATCH v15 07/12] x86/smpboot: Remove early_gdt_descr " Usama Arif
2023-03-21 14:14 ` [tip: x86/apic] " tip-bot2 for Brian Gerst
2023-03-16 22:21 ` [PATCH v15 08/12] x86/smpboot: Remove initial_gs Usama Arif
2023-03-21 14:14 ` [tip: x86/apic] " tip-bot2 for Brian Gerst
2023-03-16 22:21 ` [PATCH v15 09/12] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-03-21 18:28 ` Brian Gerst
2023-03-21 19:12 ` David Woodhouse
2023-03-21 21:02 ` Brian Gerst
2023-03-16 22:21 ` [PATCH v15 10/12] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-03-16 22:21 ` [PATCH v15 11/12] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-03-16 22:21 ` [PATCH v15 12/12] x86/smpboot: Allow parallel bringup for SEV-ES Usama Arif
2023-03-17 16:04 ` Tom Lendacky
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