RE: [Xen-ia64-devel] Faulty protection key handling

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Psr.pk is unchanged when interrupt happens.
So we still need reserve some PK registers for hypervisor.

Anthony

>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of JÃrgen Gro?
>Sent: 2007å4æ26æ 14:35
>Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: [Xen-ia64-devel] Faulty protection key handling
>
>JÃrgen Groà wrote:
>> Tristan Gingold wrote:
>>> On Wed, Apr 25, 2007 at 03:36:20PM +0200, Dietmar Hahn wrote:
>>>> Hi,
>>> [..]
>>>> By the way, are there any thoughts about adding emulation of protection 
>>>> keys
>>>> to the hypervisor? I know, whether the hypervisor nor dom0-linux are using
>>>> this but we need this stuff. I would try to write a proposal and add using
>>>> protection keys in the minios for tests. What do you think?
>>> It shouldn't be that different from RID partitions: just partition PK space
>>> like RID space is partitionned.  I really think the modifications are not
>>> that big, unless we find a blocking issue.  I will try to think more...
>>
>> Are you sure? I don't think PK space must be partitioned. Protection keys are
>> an additional feature for further access limitations of pages which are
>> already "protected" via RID.
>>
>> One issue arises with support of protection keys: the hypervisor must be able
>> to run with enabled protection keys as well (protection keys are enabled in
>> %cr.dcr which is not changed in case of interruption). So we will need an own
>> protection key value for the hypervisor and of course a reserved protection
>> key register.
>
>Sorry, PK is enables in %psr, of course, but there is no corresponding
>%cr.dcr bit for interrupt defaults.
>
>Juergen
>
>--
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