linux-kernel - Re: [PATCH 3/7] x86, lib: Add WBNOINVD helper functions

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Message-ID: <71fb365773bdc6a38120f81c1177cb27cd2bb914.camel@intel.com>
Date: Thu, 13 Mar 2025 10:13:53 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "tglx@...utronix.de" <tglx@...utronix.de>, "x86@...nel.org"
	<x86@...nel.org>, "mingo@...hat.com" <mingo@...hat.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>, "bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
CC: "szy0127@...u.edu.cn" <szy0127@...u.edu.cn>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "thomas.lendacky@....com" <thomas.lendacky@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Zhang,
 Mingwei" <mizhang@...gle.com>, "kevinloughlin@...gle.com"
	<kevinloughlin@...gle.com>
Subject: Re: [PATCH 3/7] x86, lib: Add WBNOINVD helper functions

On Wed, 2025-02-26 at 17:48 -0800, Sean Christopherson wrote:
> From: Kevin Loughlin <kevinloughlin@...gle.com>
> 
> In line with WBINVD usage, add WBONINVD helper functions.  Fall back to
> WBINVD (via alternative()) if WBNOINVD isn't supported, as WBINVD provides
> a superset of functionality, just more slowly.
> 
> Note, alternative() ensures compatibility with early boot code as needed.
> 
> Signed-off-by: Kevin Loughlin <kevinloughlin@...gle.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
> [sean: massage changelog and comments, use ASM_WBNOINVD and _ASM_BYTES]
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Kai Huang <kai.huang@...el.com>

[...]

>  static __always_inline void wbinvd(void)
>  {
> -	asm volatile("wbinvd": : :"memory");
> +	asm volatile("wbinvd" : : : "memory");
> +}
> 

Nit: this is not related, though.