linux-kernel - Re: [PATCH] x86/mm: Disable INVLPGB when PTI is enabled

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Message-ID: <1c282625-c433-4675-b934-030e33a0f6fb@intel.com>
Date: Tue, 10 Jun 2025 20:53:33 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Rik van Riel <riel@...riel.com>, Dave Hansen
 <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org
Cc: Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>,
 Ingo Molnar <mingo@...nel.org>, Nadav Amit <nadav.amit@...il.com>,
 Peter Zijlstra <peterz@...radead.org>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/mm: Disable INVLPGB when PTI is enabled

On 6/10/25 17:43, Rik van Riel wrote:
> On Tue, 2025-06-10 at 15:24 -0700, Dave Hansen wrote:
>> Disable INVLPGB if PTI is enabled. Avoid overrunning the small
>> bitmap.
>>
>> Note: this will be fixed up properly by making the bitmap bigger.
>> For now, just avoid the mostly theoretical bug.
>>
> Does that mean the patch to make the bitmap bigger
> is a dependency that needs to be in place before
> the RAR code (hoping to send out v4 later this week)
> can be merged?

That's what I was thinking. Your series to fix this all up properly from
last week looks like the right way. It just seems like a wee bit more
work than I want to see getting backported. It's not a huge lift, though.