linux-kernel - Re: [PATCHv8 04/17] x86/cpu: Defer CR pinning setup until after EFI initialization

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Message-ID: <ysoozflaqr3rnb2kjqca5ifeuc7clutiaypqraqs7r4sdumxmi@uc2bp7l5th75>
Date: Fri, 4 Jul 2025 15:23:23 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Andy Lutomirski <luto@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
	Peter Zijlstra <peterz@...radead.org>, Ard Biesheuvel <ardb@...nel.org>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Xiongwei Song <xiongwei.song@...driver.com>, Xin Li <xin3.li@...el.com>, 
	"Mike Rapoport (IBM)" <rppt@...nel.org>, Brijesh Singh <brijesh.singh@....com>, 
	Michael Roth <michael.roth@....com>, Tony Luck <tony.luck@...el.com>, 
	Alexey Kardashevskiy <aik@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
	Jonathan Corbet <corbet@....net>, Sohil Mehta <sohil.mehta@...el.com>, 
	Ingo Molnar <mingo@...nel.org>, Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, 
	Daniel Sneddon <daniel.sneddon@...ux.intel.com>, Kai Huang <kai.huang@...el.com>, 
	Sandipan Das <sandipan.das@....com>, Breno Leitao <leitao@...ian.org>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Alexei Starovoitov <ast@...nel.org>, 
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	Yuntao Wang <ytcoode@...il.com>, Rasmus Villemoes <linux@...musvillemoes.dk>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, Tejun Heo <tj@...nel.org>, Changbin Du <changbin.du@...wei.com>, 
	Huang Shijie <shijie@...amperecomputing.com>, Geert Uytterhoeven <geert+renesas@...der.be>, 
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	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org, 
	linux-mm@...ck.org
Subject: Re: [PATCHv8 04/17] x86/cpu: Defer CR pinning setup until after EFI
 initialization

On Wed, Jul 02, 2025 at 01:05:23PM +0300, Kirill A. Shutemov wrote:
> On Tue, Jul 01, 2025 at 04:10:19PM -0700, Dave Hansen wrote:
> > On 7/1/25 02:58, Kirill A. Shutemov wrote:
> > > Move CR pinning setup behind the EFI initialization.
> > 
> > I kinda grumble about these one-off solutions. Could we just do this
> > once and for all and defer CR pinning as long as possible? For instance,
> > could we do it in a late_initcall()?
> > 
> > Do we need pinning before userspace comes up?
> 
> Hm. I operated from an assumption that we want to pin control registers as
> early as possible to get most benefit from it.
> 
> I guess we can defer it until later. But I am not sure late_initcall() is
> the right place. Do we want random driver to twiddle control registers?

I will do it in core_initcall().

-- 
  Kiryl Shutsemau / Kirill A. Shutemov