Re: [PATCH 0/4] XSA-52..54 follow-up

[George Dunlap <george.dunlap@eu.citrix.com>]

On 06/04/2013 11:45 AM, Jan Beulich wrote:
>>>> On 04.06.13 at 12:09, George Dunlap <george.dunlap@eu.citrix.com> wrote:
>> On 06/04/2013 11:00 AM, Keir Fraser wrote:
>>> On 04/06/2013 08:58, "Jan Beulich" <JBeulich@suse.com> wrote:
>>>
>>>> The first patch really isn't as much of a follow-up than what triggered
>>>> the security issues to be noticed in the first place.
>>>>
>>>> 1: x86: preserve FPU selectors for 32-bit guest code
>>>> 2: x86: fix XCR0 handling
>>>> 3: x86/xsave: adjust state management
>>>> 4: x86/fxsave: bring in line with recent xsave adjustments
>>>>
>>>> The first two I would see as candidates for 4.3 (as well as
>>>> subsequent backporting, albeit I realize that especially the first
>>>> one is non-trivial), while the third is code improvement only,
>>>> and the fourth is really just cleanup, and hence I'd be fine with
>>>> deferring them until after 4.3.
>>>>
>>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>>
>>> I like the patches, 1 & 2 are good bug fixes.
>>> Acked-by: Keir Fraser <keir@xen.org>
>>>
>>> Patch #1 is quite scary though! I wonder really whether these long-lived
>>> issues must be fixed right now, let alone backported?
>>
>> Yeah, I was going to say, with all this tricky code going in, including
>> this one, and the XSA-55 (?) one that seems to have tons of tricky
>> changes, whether it might not be a good idea to make sure we have at
>> least 2 weeks of testing and another test day -- or, delay the test day
>> Wednesday until we can get all of these in.
>
> Agreed, but I don't know what implications delaying a Test Day
> would have. We certainly don't want to release in a rush with all
> these new fixes.
>
>> Jan, looking at the comments, it seems like 3 and 4 are more about
>> performance than correctness?  I think those should probably wait until
>> the 4.4 dev window opens up.
>
> Yes, as I also said in the overview description above. The question
> is really just about the first two to go in right away.

These seem pretty clearly like things we need to have fixed in the 
release -- they're the kind of thing that is likely to have potentially 
nasty, hard-to-track-down side effects.

  -George