[PATCH] arm: kernel: sleep: restore HYP mode configuration in cpu_resume

[Marc Zyngier]

On Tue, Mar 04 2014 at  6:23:33 pm GMT, Lorenzo Pieralisi <Lorenzo.Pieralisi at arm.com> wrote:
> On CPUs with virtualization extensions the kernel installs HYP mode
> configuration on both primary and secondary cpus upon cold boot.
>
> On platforms where CPUs are shutdown in idle paths (ie CPU core gating),
> when a CPU resumes from low-power states it currently does not execute
> code that reinstalls the HYP configuration, which means that the kernel
> cannot run eg KVM properly on such machines.
>
> This patch, mirroring cold-boot behaviour, executes position independent
> code that reinstalls HYP configuration and drops to SVC mode safely on
> warmboot, so that deep idle states can be enabled in kernel running as
> hosts on platforms with power management HW.
>
> Cc: Christoffer Dall <christoffer.dall at linaro.org>
> Cc: Dave Martin <dave.martin at arm.com>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Cc: Nicolas Pitre <nico at linaro.org>
> Cc: Russell King <linux at arm.linux.org.uk>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>

Look sensible to me.

Acked-by: Marc Zyngier <marc.zyngier at arm.com>

	M.

> ---
>  arch/arm/kernel/sleep.S | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
> index b907d9b..1b880db 100644
> --- a/arch/arm/kernel/sleep.S
> +++ b/arch/arm/kernel/sleep.S
> @@ -127,6 +127,10 @@ ENDPROC(cpu_resume_after_mmu)
>  	.align
>  ENTRY(cpu_resume)
>  ARM_BE8(setend be)			@ ensure we are in BE mode
> +#ifdef CONFIG_ARM_VIRT_EXT
> +	bl	__hyp_stub_install_secondary
> +#endif
> +	safe_svcmode_maskall r1
>  	mov	r1, #0
>  	ALT_SMP(mrc p15, 0, r0, c0, c0, 5)
>  	ALT_UP_B(1f)
> @@ -144,7 +148,6 @@ ARM_BE8(setend be)			@ ensure we are in BE mode
>  	ldr	r0, [r0, #SLEEP_SAVE_SP_PHYS]
>  	ldr	r0, [r0, r1, lsl #2]
>  
> -	setmode	PSR_I_BIT | PSR_F_BIT | SVC_MODE, r1  @ set SVC, irqs off
>  	@ load phys pgd, stack, resume fn
>    ARM(	ldmia	r0!, {r1, sp, pc}	)
>  THUMB(	ldmia	r0!, {r1, r2, r3}	)

-- 
AAAFNRAA