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

[Tristan Gingold <tgingold@xxxxxxx>]

> Are you sure?
> VTI and PV implementation will both need a PKR for hypervisor.
> PV could know about this PKR and it's value, so PV would use only 15 other
> PKRs.
> VTI will use one PKR for the trap vector. The hypervisor should be able to
> detect this special PKR and remember the PK value. In the PKR emulation PKR 0
> and the VTI special PKR could be swapped, as well as the VTI PK value and
> PK value 0.
It should rather easy to detect which PK is used for the OS: the PK for the
ivt.

> Example:
> VTI domain uses PKR 3 with value 123 for its trap vector.
> If VTI domain accesses PKR 3, real PKR 0 is used, VTI access to PKR 0 will use
> real PKR 3.
> Real PK value 0 is presented as PKR value 123 to VTI domain, while real PK
> value 123 is presented as 0.
That should work as long as the OS doesn't change its own PK, otherwise you
have to flush.

Anyway this sounds clever, I buy it!

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