Re: [PATCH 2/2] KVM: PPC: epapr: Install ev_idle hcall for paravirt

[Scott Wood <scottwood@freescale.com>]

On 12/31/2011 12:16 AM, Liu Yu wrote:
> If the guest hypervisor node contains "has-idle" property.
> 
> Signed-off-by: Liu Yu <yu.liu@freescale.com>
> ---
>  arch/powerpc/kernel/kvm.c |   29 +++++++++++++++++++++++++++++
>  1 files changed, 29 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
> index b06bdae..258f129 100644
> --- a/arch/powerpc/kernel/kvm.c
> +++ b/arch/powerpc/kernel/kvm.c
> @@ -28,6 +28,7 @@
>  #include <asm/sections.h>
>  #include <asm/cacheflush.h>
>  #include <asm/disassemble.h>
> +#include <asm/machdep.h>
>  
>  #define KVM_MAGIC_PAGE		(-4096L)
>  #define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
> @@ -571,6 +572,30 @@ static __init void kvm_free_tmp(void)
>  	}
>  }
>  
> +static void kvm_hcall_ev_idle(void)
> +{
> +	ulong in[8];
> +	ulong out[8];
> +
> +	current_thread_info()->local_flags |= _TLF_NAPPING;
> +	local_irq_enable();
> +	kvm_hypercall(in, out, HC_VENDOR_EPAPR | HC_EV_IDLE);
> +}

I think this has to be done in assembly -- otherwise it's not safe for
the interrupt handler to return directly to LR.

> +static int kvm_para_ev_has_idle(void)
> +{
> +	struct device_node *hyper_node;
> +
> +	hyper_node = of_find_node_by_path("/hypervisor");
> +	if (!hyper_node)
> +		return 0;
> +
> +	if (of_get_property(hyper_node, "has-idle", NULL))
> +		return 1;
> +
> +	return 0;
> +}

Since this is standardized in ePAPR, can we move it out of kvm.c an into
generic code to work with any hypervisor that sets has-idle?  Likewise
with kvm_para_setup().

-Scott