linux-kernel - Re: [PATCH RESEND] x86/xen: enable early use of set

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Date:   Mon, 20 Aug 2018 19:20:17 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org
Cc:     hpa@...or.com, tglx@...utronix.de, mingo@...hat.com
Subject: Re: [PATCH RESEND] x86/xen: enable early use of set_fixmap in 32-bit
 Xen PV guest

On 08/20/2018 11:24 AM, Juergen Gross wrote:
> Commit 7b25b9cb0dad83 ("x86/xen/time: Initialize pv xen time in
> init_hypervisor_platform()") moved the mapping of the shared info area
> before pagetable_init(). This breaks booting as 32-bit PV guest as the
> use of set_fixmap isn't possible at this time on 32-bit.
>
> This can be worked around by populating the needed PMD on 32-bit
> kernel earlier.
>
> In order not to reimplement populate_extra_pte() using extend_brk()
> for allocating new page tables extend alloc_low_pages() to do that in
> case the early page table pool is not yet available.
>
> Fixes: 7b25b9cb0dad83 ("x86/xen/time: Initialize pv xen time in init_hypervisor_platform()")
> Signed-off-by: Juergen Gross <jgross@...e.com>
> Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> Resending with corrected Fixes: tag
> Boris, please take this via the Xen tree (Thomas asked us to do so)

Applied to for-linus-19b.

-boris