Re: [Xen-devel] [PATCH 0/3] x86: nuke PV superpage support

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/07/17 16:41, Wei Liu wrote:
> On Mon, Jul 24, 2017 at 04:22:52PM +0100, Wei Liu wrote:
>> On Mon, Jul 24, 2017 at 04:01:55PM +0100, Andrew Cooper wrote:
>>> On 24/07/17 15:44, Wei Liu wrote:
>>>> On Mon, Jul 24, 2017 at 03:25:22PM +0100, Andrew Cooper wrote:
>>>>> On 24/07/17 15:02, Wei Liu wrote:
>>>>>> Wei Liu (3):
>>>>>>   x86: nuke PV superpage option and code
>>>>>>   tools: nuke superpage parameters in code
>>>>>>   docs: delete PV superpage option
>>>>> If you are doing this, can you modify
>>>>> xc_sr_save_x86_pv.c:normalise_pagetable() to fail immediately if a
>>>>> superpage is found.  Currently, this condition is deferred until the
>>>>> live phase is complete.
>>>>>
>>>> Why was it done like that in the first place?
>>> Because if a PV guest shatters all of its superpages during the live
>>> phase, it can be successfully moved.
>>>
>>> This work was mixed up in the question of the time as to whether PV
>>> migraiton worked with superpages at all, seeing as the legacy code took
>>> a (non-working) stab at attempting the migration.
>>>
>> OK. This makes sense. I will submit a separate patch for the thing you
>> asked for, since it is more like an improvement to the code.
> ---8<---
> From fd4934b754eb3a1b8a98167aa4432a105caac185 Mon Sep 17 00:00:00 2001
> From: Wei Liu <wei.liu2@xxxxxxxxxx>
> Date: Mon, 24 Jul 2017 16:35:09 +0100
> Subject: [PATCH] libxc: bail immediately when PV superpage is discovered
>
> The original code was added with the hope that PV superpage migration
> might work. But it was never proven that the code actually worked.
>
> Now that PV superpage is gone, simplify the code by returning error
> immediately.
>
> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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