Re: [RFC v5 14/38] powerpc: initial plumbing for key management

On Fri, Jul 14, 2017 at 6:37 AM, Ram Pai [off-list ref] wrote:

On Thu, Jul 13, 2017 at 12:45:00AM -0700, Ram Pai wrote:

quoted

On Wed, Jul 12, 2017 at 01:28:25PM +1000, Balbir Singh wrote:

quoted

On Wed,  5 Jul 2017 14:21:51 -0700
Ram Pai [off-list ref] wrote:

quoted

Initial plumbing to manage all the keys supported by the
hardware.

Total 32 keys are supported on powerpc. However pkey 0,1
and 31 are reserved. So effectively we have 29 pkeys.

This patch keeps track of reserved keys, allocated  keys
and keys that are currently free.

It looks like this patch will only work in guest mode?
Is that an assumption we've made? What happens if I use
keys when running in hypervisor mode?

It works in supervisor mode, as a guest aswell as a bare-metal
kernel. Whatever needs to be done in hypervisor mode
is already there in power-kvm.

I realize i did not answer your question accurately...
"What happens if I use keys when running in hypervisor mode?"

Its not clear what happens. As far as I can tell the MMU does
not check key violation when in hypervisor mode. So effectively
I think, keys are ineffective when in hypervisor mode.

keys are honored in hypervisor mode. I was just
stating that we need a mechanism used by the hypervisor
to partition the key space between guests and hypervisor.

Balbir Singh