linux-kernel - Re: [PATCH v5 00/12] AMD broadcast TLB invalidation

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Message-ID: <20250116223748.GA33629@noisy.programming.kicks-ass.net>
Date: Thu, 16 Jan 2025 23:37:48 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Michael Kelley <mhklinux@...look.com>
Cc: "riel@...riel.com" <riel@...riel.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"zhengqi.arch@...edance.com" <zhengqi.arch@...edance.com>,
	"nadav.amit@...il.com" <nadav.amit@...il.com>,
	"thomas.lendacky@....com" <thomas.lendacky@....com>,
	"kernel-team@...a.com" <kernel-team@...a.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"jannh@...gle.com" <jannh@...gle.com>,
	"andrew.cooper3@...rix.com" <andrew.cooper3@...rix.com>
Subject: Re: [PATCH v5 00/12] AMD broadcast TLB invalidation

On Thu, Jan 16, 2025 at 06:14:00PM +0000, Michael Kelley wrote:
> So CoCo
> VMs may still use the paravirtualization that makes hypercalls to do
> TLB flushes. It's future work to *always* use INVLPGB (if available)
> in a CoCo VM.

That would place a limit on the number of CPUs, to be no larger than the
number of available ASIDs.