On Tue, Feb 06, 2018 at 01:39:06PM +0100, Christoffer Dall wrote:
> Hi Mark,
>
> On Mon, Nov 27, 2017 at 04:37:59PM +0000, Mark Rutland wrote:
> > To allow EL0 (and/or EL1) to use pointer authentication functionality,
> > we must ensure that pointer authentication instructions and accesses to
> > pointer authentication keys are not trapped to EL2 (where we will not be
> > able to handle them).
>
> ...on non-VHE systems, presumably?
For EL0 usage, we don't want to trap even in the absence of VHE, so I'll
drop the bit in brackets entirely.
> > This patch ensures that HCR_EL2 is configured appropriately when the
> > kernel is booted at EL2. For non-VHE kernels we set HCR_EL2.{API,APK},
> > ensuring that EL1 can access keys and permit EL0 use of instructions.
> > For VHE kernels, EL2 access is controlled by EL3, and we need not set
> > anything.
>
>
> for VHE kernels host EL0 (TGE && E2H) is unaffected by these settings,
> and it doesn't matter how we configure HCR_EL2.{API,APK}.
>
> (Because you do actually set these bits when the features are present if
> I read the code correctly).
Ah, true. I've taken your proposed wording.
> > This does not enable support for KVM guests, since KVM manages HCR_EL2
> > itself.
>
> (...when running VMs.)
>
>
> Besides the nits:
>
> Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Cheers!
Mark.
