Hi,

On 5/21/19 7:43 PM, Yasser Shalabi wrote:
> Yeah, sorry been caught up and lost track of doing this. Will do it ASAP. 
> 
> I’ll will also try to add some code to dynamically determine PKE support
> to avoid setting it for older platforms (Jan previously requested this).

in Jan's last mail, he wrote that your original patch is fine:

> Checking the code again and the comment I wrote around it, my
> remark in github that we would need discovery was actually overkill:
> The whole purpose of X86_CR4_RESERVED is to filter out future unknown
> bits. But CR4.PKE is no longer unknown, and it is apparently safe to
> allow it to the root cell. IOW, that commit was fine (if it had been
> submitted

  Ralf

> 
> Thanks for the reminder.
> 
> Yasser
> 
> On Tue, May 21, 2019 at 12:38 PM Ralf Ramsauer
> <[email protected]
> <mailto:[email protected]>> wrote:
> 
>     Hi Yasser,
> 
>     I hit the same CR4 PKE-bit case as you did a month ago.
> 
>     May I ask you to resend the patch (with a Signed-Off line) to the
>     mailing list?
> 
>     Thanks
>       Ralf
> 
>     On 5/21/19 6:38 PM, Jan Kiszka wrote:
>     > On 21.05.19 17:55, Ralf Ramsauer wrote:
>     >>
>     >>
>     >> On 5/21/19 5:09 PM, Jan Kiszka wrote:
>     >>> On 21.05.19 15:45, Ralf Ramsauer wrote:
>     >>>> Hi,
>     >>>>
>     >>>> we have some issues enabling Jailhouse on a Intel with a pretty
>     new CPU
>     >>>> (Xeon Gold 5118).
>     >>>>
>     >>>> First, the CPU supports PKE and Linux will enable it (CR4, Bit 22).
>     >>>> Jailhouse won't start, as this bit is marked in X86_CR4_RESERVED.
>     >>>> Didn't
>     >>>> have a deeper look into this on how it affects the hypervisor or
>     >>>> allowing it needs some special treatment, so adding nopku to the
>     >>>> commandline will keep the feature disabled and suffices for the
>     moment.
>     >>>>
>     >>>
>     >>> Known issue, see https://github.com/siemens/jailhouse/pull/23
>     >>
>     >> Aah, I remember that discussion a month ago...
>     >>
>     >> So I guess it is okay to allow this feature.
>     >>
>     >> What would you say, is it better to use a configuration parameter
>     that
>     >> indicates the existence of PKE (as noted in the github discussion, we
>     >> should only respect that bit if available), or online cpuid
>     discovery?
>     >>
>     >> I guess the latter one is a bit against the philosophy, but much
>     simpler
>     >> to implement.
>     >>
>     >
>     > Checking the code again and the comment I wrote around it, my
>     remark in
>     > github that we would need discovery was actually overkill: The whole
>     > purpose of X86_CR4_RESERVED is to filter out future unknown bits. But
>     > CR4.PKE is no longer unknown, and it is apparently safe to allow it to
>     > the root cell. IOW, that commit was fine (if it had been submitted
>     with
>     > signed-off here).
>     >
>     > Jan
>     >
> 
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