From: Peter Zijlstra <peterz@infradead.org>
To: Valentin Schneider <vschneid@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
kvm@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org,
x86@kernel.org, rcu@vger.kernel.org,
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"Steven Rostedt" <rostedt@goodmis.org>,
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"Petr Tesarik" <ptesarik@suse.com>
Subject: Re: [RFC PATCH v3 08/15] sched/clock, x86: Make __sched_clock_stable forceful
Date: Thu, 21 Nov 2024 12:02:42 +0100 [thread overview]
Message-ID: <20241121110242.GD24774@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <xhsmhv7whhnjb.mognet@vschneid-thinkpadt14sgen2i.remote.csb>
On Wed, Nov 20, 2024 at 05:34:32PM +0100, Valentin Schneider wrote:
> On 20/11/24 15:59, Peter Zijlstra wrote:
> > On Tue, Nov 19, 2024 at 04:34:55PM +0100, Valentin Schneider wrote:
> >> Later commits will cause objtool to warn about non __ro_after_init static
> >> keys being used in .noinstr sections in order to safely defer instruction
> >> patching IPIs targeted at NOHZ_FULL CPUs.
> >>
> >> __sched_clock_stable is used in .noinstr code, and can be modified at
> >> runtime (e.g. KVM module loading). Suppressing the text_poke_sync() IPI has
> >
> > Wait, what !? loading KVM causes the TSC to be marked unstable?
>
> There is however this:
>
> kvm_arch_vcpu_load()
> `\
> mark_tsc_unstable()
>
> So plugging a VCPU might do that.
Right, but that only happens if it observes the TSC doing dodgy, so
that's deserved and shouldn't happen on hardware from this decade, and
possibly the one before that.
next prev parent reply other threads:[~2024-11-21 11:03 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-19 15:34 [RFC PATCH v3 00/15] context_tracking,x86: Defer some IPIs until a user->kernel transition Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 01/15] objtool: Make validate_call() recognize indirect calls to pv_ops[] Valentin Schneider
2024-11-19 20:38 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 02/15] objtool: Flesh out warning related to pv_ops[] calls Valentin Schneider
2024-11-19 20:38 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 03/15] sched/clock: Make sched_clock_running __ro_after_init Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 04/15] rcu: Add a small-width RCU watching counter debug option Valentin Schneider
2024-11-20 14:50 ` Peter Zijlstra
2024-11-20 16:15 ` Valentin Schneider
2024-11-22 12:53 ` Paul E. McKenney
2024-11-22 13:56 ` Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 05/15] rcutorture: Make TREE04 use CONFIG_RCU_DYNTICKS_TORTURE Valentin Schneider
2024-11-22 12:54 ` Paul E. McKenney
2024-11-19 15:34 ` [RFC PATCH v3 06/15] jump_label: Add forceful jump label type Valentin Schneider
2024-11-19 23:39 ` Josh Poimboeuf
2024-11-20 14:56 ` Peter Zijlstra
2024-11-20 14:57 ` Peter Zijlstra
2024-11-20 16:55 ` Josh Poimboeuf
2024-11-21 11:00 ` Peter Zijlstra
2024-11-21 15:38 ` Josh Poimboeuf
2024-11-21 15:51 ` Valentin Schneider
2024-11-21 20:21 ` Josh Poimboeuf
2024-11-22 10:17 ` Valentin Schneider
2024-11-20 16:24 ` Valentin Schneider
2024-11-20 0:05 ` Josh Poimboeuf
2024-11-20 10:22 ` Peter Zijlstra
2024-11-19 15:34 ` [RFC PATCH v3 07/15] x86/speculation/mds: Make mds_idle_clear forceful Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 08/15] sched/clock, x86: Make __sched_clock_stable forceful Valentin Schneider
2024-11-20 14:59 ` Peter Zijlstra
2024-11-20 16:34 ` Valentin Schneider
2024-11-21 11:02 ` Peter Zijlstra [this message]
2024-11-19 15:34 ` [RFC PATCH v3 09/15] objtool: Warn about non __ro_after_init static key usage in .noinstr Valentin Schneider
2024-11-20 17:13 ` Josh Poimboeuf
2024-11-19 15:34 ` [RFC PATCH v3 10/15] x86/alternatives: Record text_poke's of JUMP_TYPE_FORCEFUL labels Valentin Schneider
2024-11-19 15:34 ` [RFC PATCH v3 11/15] context-tracking: Introduce work deferral infrastructure Valentin Schneider
2024-11-20 10:54 ` Frederic Weisbecker
2024-11-20 14:23 ` Frederic Weisbecker
2024-11-20 17:10 ` Valentin Schneider
2024-11-20 17:30 ` Frederic Weisbecker
2024-11-22 14:56 ` Valentin Schneider
2024-11-24 21:46 ` Frederic Weisbecker
2024-11-29 16:40 ` Valentin Schneider
2024-11-29 22:19 ` Frederic Weisbecker
2024-11-19 15:34 ` [RFC PATCH v3 12/15] context_tracking,x86: Defer kernel text patching IPIs Valentin Schneider
2024-11-20 15:13 ` Peter Zijlstra
2024-11-19 15:35 ` [RFC PATCH v3 13/15] context_tracking,x86: Add infrastructure to defer kernel TLBI Valentin Schneider
2024-11-20 15:22 ` Peter Zijlstra
2024-11-20 15:32 ` Peter Zijlstra
2024-11-20 17:24 ` Valentin Schneider
2024-11-21 11:12 ` Peter Zijlstra
2024-11-21 15:07 ` Dave Hansen
2024-11-21 15:30 ` Peter Zijlstra
2024-12-05 17:31 ` Petr Tesarik
2024-12-09 12:04 ` Valentin Schneider
2024-12-09 12:12 ` Peter Zijlstra
2024-12-09 14:42 ` Petr Tesarik
2024-12-10 13:53 ` Valentin Schneider
2024-12-10 14:42 ` Petr Tesarik
2024-12-09 12:33 ` Petr Tesarik
2024-11-21 16:26 ` Peter Zijlstra
2024-11-19 15:35 ` [RFC PATCH v3 14/15] x86/mm, mm/vmalloc: Defer flush_tlb_kernel_range() targeting NOHZ_FULL CPUs Valentin Schneider
2024-11-19 15:35 ` [RFC PATCH v3 15/15] context-tracking: Add a Kconfig to enable IPI deferral for NO_HZ_IDLE Valentin Schneider
2024-11-19 16:45 ` [RFC PATCH v3 00/15] context_tracking,x86: Defer some IPIs until a user->kernel transition Steven Rostedt
2024-11-19 22:51 ` Valentin Schneider
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