linux-kernel - Re: [PATCH] x86/boot/64: Initialize 5-level paging variables earlier

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Message-ID: <20201012140830.vrc25x2gwo7yo4kn@black.fi.intel.com>
Date:   Mon, 12 Oct 2020 17:08:30 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     x86@...nel.org, Joerg Roedel <jroedel@...e.de>,
        Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/boot/64: Initialize 5-level paging variables earlier

On Sat, Oct 10, 2020 at 03:26:24PM -0400, Arvind Sankar wrote:
> On Sat, Oct 10, 2020 at 03:11:10PM -0400, Arvind Sankar wrote:
> > Commit
> >   ca0e22d4f011 ("x86/boot/compressed/64: Always switch to own page table")
> > started using a new set of pagetables even without KASLR.
> > 
> > After that commit, initialize_identity_maps() is called before the
> > 5-level paging variables are setup in choose_random_location(), which
> > will not work if 5-level paging is actually enabled.
> 
> Note that I don't have hardware that supports 5-level paging, so this
> is not actually tested with 5-level, but based on code inspection, it
> shouldn't work.

qemu supports it. -cpu "qemu64,+la57"

-- 
 Kirill A. Shutemov