linux-kernel - Re: [PATCH] x86/64/mm: Map all kernel memory into trampoline

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Message-ID: <YUHd3kGUngaB758q@8bytes.org>
Date:   Wed, 15 Sep 2021 13:49:50 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        hpa@...or.com, jroedel@...e.de,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] x86/64/mm: Map all kernel memory into trampoline_pgd

Hi Mike,

On Tue, Sep 14, 2021 at 10:52:39AM +0300, Mike Rapoport wrote:
> On Mon, Sep 13, 2021 at 11:52:36AM +0200, Joerg Roedel wrote:
> > +	for (i = pgd_index(__PAGE_OFFSET); i < PTRS_PER_PGD; i++)
> > +		trampoline_pgd[i] = init_top_pgt[i].pgd;
> 
> Don't we need to update the trampoline_pgd in sync_global_pgds() as well?

No, the trampoline_pgd is setup after preallocate_vmalloc_pages(), so
everything that would need synchronization is already in the reference
page-table.

Regards,

	Joerg