Re: [Xen-devel] [PATCH] x86/xen: Initialize cr4 shadow for 64-bit PV(H) guests

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On March 3, 2015 1:15:42 PM EST, "Luis R. Rodriguez" <mcgrof@suse.com> wrote:
>On Tue, Mar 03, 2015 at 09:27:34AM -0500, Boris Ostrovsky wrote:
>> On 03/03/2015 12:35 AM, Luis R. Rodriguez wrote:
>>> On Mon, Feb 23, 2015 at 9:09 AM, David Vrabel
><david.vrabel@citrix.com> wrote:
>>>> On 23/02/15 16:01, Boris Ostrovsky wrote:
>>>>> Commit 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
>>>>> introduced CR4 shadows.
>>>>>
>>>>> These shadows are initialized in early boot code. The commit
>missed
>>>>> initialization for 64-bit PV(H) guests that this patch adds.
>>>> Applied to stable/for-linus-4.0, thanks.
>>>>
>>>> Boris, can you kick of a set of tests on this branch, please?
>>> Do we know worst case what should blow up without this commit ?
>>
>> PVH guest will crash.
>
>Oh wow that is serious. And this is a reactive measure to a change
>upstream,
>it might be hard but it'd be nice if we can have a proactive
>architecture
>to address this. Don't mind me though, I realize this seems hard, just 
>thinking out loud right now. Did you find it through code inspection or
>a test?

Boris runs every night on different hardware an regression test against the latest Linux kernel.

>
>  Luis

L