linux-kernel - Re: [PATCH v13 06/14] x86/mm: use broadcast TLB flushing for page reclaim TLB flushing

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Message-ID: <680053d3-4cf9-534a-1c52-c6e259b85452@amd.com>
Date: Wed, 26 Feb 2025 11:00:02 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Borislav Petkov <bp@...en8.de>, Rik van Riel <riel@...riel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, peterz@...radead.org,
 dave.hansen@...ux.intel.com, zhengqi.arch@...edance.com,
 nadav.amit@...il.com, kernel-team@...a.com, linux-mm@...ck.org,
 akpm@...ux-foundation.org, jackmanb@...gle.com, jannh@...gle.com,
 mhklinux@...look.com, andrew.cooper3@...rix.com, Manali.Shukla@....com,
 mingo@...nel.org
Subject: Re: [PATCH v13 06/14] x86/mm: use broadcast TLB flushing for page
 reclaim TLB flushing

On 2/25/25 15:03, Borislav Petkov wrote:
> On Tue, Feb 25, 2025 at 09:38:03PM +0100, Borislav Petkov wrote:
>> On Tue, Feb 25, 2025 at 02:17:20PM -0500, Rik van Riel wrote:
>>> Who do we need to ask to confirm that reading?
>>
>> Lemme figure it out.
> 
> Confirmed - that really is the case.

Hmmm... since this is for host/hypervisor TLB handling, this makes me
think that we should always be setting the ASID valid bit with 0 for the
ASID value in EDX[15:0] on all INVLPGB instructions in this series.
Otherwise we will also be flushing any guest ASID TLB entries that match
the conditions, when that isn't intended.

Thanks,
Tom

> 
> Thx.
>