linux-kernel - Re: [PATCH v2 3/4] x86/mm: Flush global TLB when switching to trampoline page-table

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Message-ID: <YVcBGYKQU5dFggvy@8bytes.org>
Date:   Fri, 1 Oct 2021 14:37:45 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        hpa@...or.com, Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Joerg Roedel <jroedel@...e.de>,
        Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] x86/mm: Flush global TLB when switching to
 trampoline page-table

On Wed, Sep 29, 2021 at 08:07:10AM -0700, Dave Hansen wrote:
> 	/*
> 	 * The CR3 writes above may not flush global TLB entries.
> 	 * Stale, global entries from previous sets of page tables may
> 	 * still be present.  Flush those stale entries.
> 	 *
> 	 * This ensures that memory accessed while running with
> 	 * trampoline_pgd is *actually* mapped into trampoline_pgd.
> 	 */

Yes, this is better. I replaced my comment with this one (only did some
minor rewording).

Thanks,

	Joerg