[Android-virt] [PATCH 05/10] ARM: KVM: Allow the host to use the physical timer from PL1

[c.dall at virtualopensystems.com (Christoffer Dall)]

On Mon, May 14, 2012 at 9:07 AM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> As the host kernel has to move its timer from virtual to physical,
> let's make sure it has access to it. Otherwise, it would blow
> at a very early stage.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
> ?arch/arm/kvm/init.S | ? ?5 +++++
> ?1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S
> index 0bcc739..ce477ba 100644
> --- a/arch/arm/kvm/init.S
> +++ b/arch/arm/kvm/init.S
> @@ -101,6 +101,11 @@ __do_hyp_init:
> ? ? ? ?mcr ? ? p15, 4, r0, c1, c0, 0 ? @ HSCR
> ? ? ? ?isb
>
> + ? ? ? @ make CNTP_* and CNTPCT accessible from PL1
> + ? ? ? mrc ? ? p15, 4, r0, c14, c1, 0 ?@ CNTHCTL
> + ? ? ? orr ? ? r0, r0, #3 ? ? ? ? ? ? ?@ PL1PCEN | PL1PCTEN
> + ? ? ? mcr ? ? p15, 4, r0, c14, c1, 0 ?@ CNTHCTL
> +
> ? ? ? ?@ Set stack pointer and return to the kernel
> ? ? ? ?pop ? ? {r0, r1, r2, r12}
> ? ? ? ?mov ? ? sp, r1
> --
> 1.7.7.1
>
I'm not reviewing patches 1 through 4 as I am not experienced with the
workings of architected timers in the kernel in general.

I suggest sending that preparatory patch sequence separately to the
arm-kernel mailing list or somewhere appropriate for this purpose?

These bits should be 1 at reset anyway right? Why do we need to set them again?

-Christoffer