linux-kernel - Re: [PATCH v11 00/12] AMD broadcast TLB invalidation

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Message-ID: <5d6130a40f173e341306faca897a0e42f8cd5a20.camel@surriel.com>
Date: Thu, 13 Feb 2025 15:02:40 -0500
From: Rik van Riel <riel@...riel.com>
To: Brendan Jackman <jackmanb@...gle.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, bp@...en8.de, 
	peterz@...radead.org, dave.hansen@...ux.intel.com,
 zhengqi.arch@...edance.com, 	nadav.amit@...il.com, thomas.lendacky@....com,
 kernel-team@...a.com, 	linux-mm@...ck.org, akpm@...ux-foundation.org,
 jannh@...gle.com, 	mhklinux@...look.com, andrew.cooper3@...rix.com
Subject: Re: [PATCH v11 00/12] AMD broadcast TLB invalidation

On Thu, 2025-02-13 at 19:31 +0100, Brendan Jackman wrote:
> On Thu, 13 Feb 2025 at 17:20, Rik van Riel <riel@...riel.com> wrote:
> > 
> > Add support for broadcast TLB invalidation using AMD's INVLPGB
> > instruction.
> 
> Oh - what if the user sets nopcid. We need to disable invlpgb in that
> case right?
> 
That's automatic, when !X86_FEATURE_PCID,
choose_new_asid() always returns 0, and
we never assign a global ASID to a task
on any CPU.

I suppose we could make "nopcid" a little
more efficient by short-circuiting the
code in consider_global_asid() as well,
but it should already work correctly.

Peter, do you prefer a v12, or should
additional small fixes and improvements
just be sent in follow-up patches at
this point?

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