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Subject: Re: [PATCH RESEND] x86/xen: enable early use of set_fixmap in 32-bit
 Xen PV guest
To:     Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
        x86@kernel.org
Cc:     hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com
References: <20180820152420.16004-1-jgross@suse.com>
 <dd4dc3da-0d06-5844-406a-9e3d942e900d@oracle.com>
From:   Juergen Gross <jgross@suse.com>
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Message-ID: <a62903ae-566a-10b2-5b2f-4d6ca75dda91@suse.com>
Date:   Mon, 20 Aug 2018 19:05:25 +0200
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On 20/08/18 18:56, Boris Ostrovsky wrote:
> 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@suse.com>
>> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
>> ---
>> Resending with corrected Fixes: tag
>> Boris, please take this via the Xen tree (Thomas asked us to do so)
> 
> 
> Sure, but we will need to rebase to the latest bits, so you will have to
> explain yourself to Linus ;-)

NP for me. At least I hope so. :-)


Juergen