Re: [PATCH 07/19] xen/arm: Disable/enable non-boot physical CPUs on suspend/resume

[Julien Grall <julien@xxxxxxx>]

Hi,

On 07/10/2022 11:32, Mykyta Poturai wrote:
> From: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
>
> Non-boot CPUs have to be disabled on suspend and enabled on resume
> (hotplug-based mechanism). Disabling non-boot CPUs will lead to PSCI
> CPU_OFF to be called by each non-boot CPU. Depending on the underlying
> platform capabilities, this may lead to the physical powering down of
> CPUs. Tested on Xilinx Zynq Ultrascale+ MPSoC (including power down of
> each non-boot CPU).
>
> Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
> Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xxxxxxxxxx>
> ---
>   xen/arch/arm/suspend.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/suspend.c b/xen/arch/arm/suspend.c
> index 2b94816b63..0784979e4f 100644
> --- a/xen/arch/arm/suspend.c
> +++ b/xen/arch/arm/suspend.c
> @@ -13,6 +13,7 @@
>    */
>   
>   #include <xen/sched.h>
> +#include <xen/cpu.h>
>   #include <asm/cpufeature.h>
>   #include <asm/event.h>
>   #include <asm/psci.h>
> @@ -135,17 +136,29 @@ void vcpu_resume(struct vcpu *v)
>   /* Xen suspend. Note: data is not used (suspend is the suspend to RAM) */
>   static long system_suspend(void *data)
>   {
> +    int status;
> +
>       BUG_ON(system_state != SYS_STATE_active);
>   
>       system_state = SYS_STATE_suspend;
>       freeze_domains();
>   
> +    status = disable_nonboot_cpus();
> +    if ( status )
> +    {
> +        system_state = SYS_STATE_resume;
> +        goto resume_nonboot_cpus;
> +    }
> +
>       system_state = SYS_STATE_resume;
>   
> +resume_nonboot_cpus:
> +    enable_nonboot_cpus();
>       thaw_domains();
>       system_state = SYS_STATE_active;
> +    dsb(sy);
Please document what is this dsb() for.

>   
> -    return -ENOSYS;
> +    return status;
>   }
>   
>   int32_t domain_suspend(register_t epoint, register_t cid)
Cheers,

--
Julien Grall