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From: Dave Hansen <dave.hansen@intel.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	LKML <linux-kernel@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: x86/idle: Remove barriers for X86_BUG_CLFLUSH_MONITOR
Date: Wed, 2 Apr 2025 07:01:27 -0700	[thread overview]
Message-ID: <eeca95c5-5724-4205-8449-644d91eafd48@intel.com> (raw)
In-Reply-To: <20250402091017.1249019-1-andrew.cooper3@citrix.com>

On 4/2/25 02:10, Andrew Cooper wrote:
> i.e. The SDM was incorrect at the time, and barriers should not have been
> inserted.  Double checking the original AAI65 errata (not available from
> intel.com any more) shows no mention of barriers either.

There's a near copy-and-paste of that code here:

> static __cpuidle void mwait_idle(void)
> {
>         if (!current_set_polling_and_test()) {
>                 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
>                         mb(); /* quirk */
>                         clflush((void *)&current_thread_info()->flags);
>                         mb(); /* quirk */
>                 }

Any reason it can't get the same treatment?

  parent reply	other threads:[~2025-04-02 14:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-02  9:10 Andrew Cooper
2025-04-02  9:53 ` Borislav Petkov
2025-04-02 10:10 ` [tip: x86/mm] x86/idle: Remove mb() barriers for X86_BUG_CLFLUSH_MONITOR in mwait_idle_with_hints() tip-bot2 for Andrew Cooper
2025-04-02 10:17   ` Andrew Cooper
2025-04-02 14:01 ` Dave Hansen [this message]
2025-04-02 14:04   ` x86/idle: Remove barriers for X86_BUG_CLFLUSH_MONITOR Andrew Cooper

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