[PATCH v4 3/3] KVM: PPC: epapr: install ev_idle hcall for e500 guest

[Alexander Graf]

On 16.02.2012, at 10:26, Liu Yu <yu.liu at freescale.com> wrote:

> If the guest hypervisor node contains "has-idle" property.
> 
> Signed-off-by: Liu Yu <yu.liu at freescale.com>
> ---
> v4:
> 1. discard the CONFIG_E500 to make code for all powerpc platform
> 2. code cleanup
> 
> arch/powerpc/kernel/epapr.S      |   29 +++++++++++++++++++++++++++++
> arch/powerpc/kernel/epapr_para.c |   13 ++++++++++++-
> 2 files changed, 41 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/epapr.S b/arch/powerpc/kernel/epapr.S
> index 697b390..f06d636 100644
> --- a/arch/powerpc/kernel/epapr.S
> +++ b/arch/powerpc/kernel/epapr.S
> @@ -15,6 +15,35 @@
> #include <asm/ppc_asm.h>
> #include <asm/asm-offsets.h>
> 
> +#define HC_VENDOR_EPAPR        (1 << 16)
> +#define HC_EV_IDLE        16
> +
> +_GLOBAL(epapr_ev_idle)
> +epapr_ev_idle:
> +    rlwinm    r3,r1,0,0,31-THREAD_SHIFT    /* current thread_info */
> +    lwz    r4,TI_LOCAL_FLAGS(r3)    /* set napping bit */
> +    ori    r4,r4,_TLF_NAPPING    /* so when we take an exception */
> +    stw    r4,TI_LOCAL_FLAGS(r3)    /* it will return to our caller */
> +
> +    wrteei    1
> +
> +idle_loop:
> +    LOAD_REG_IMMEDIATE(r11, HC_VENDOR_EPAPR | HC_EV_IDLE)
> +
> +.global epapr_ev_idle_start
> +epapr_ev_idle_start:
> +    li    r3, -1
> +    nop
> +    nop
> +    nop

Can't you just bl into epapr_hypercall_start? You don't even have to save the old lr. because we never return anyways :)

Alex

> +
> +    /*
> +     * Guard against spurious wakeups (e.g. from a hypervisor) --
> +     * any real interrupt will cause us to return to LR due to
> +     * _TLF_NAPPING.
> +     */
> +    b    idle_loop
> +
> /* Hypercall entry point. Will be patched with device tree instructions. */
> .global epapr_hypercall_start
> epapr_hypercall_start:
> diff --git a/arch/powerpc/kernel/epapr_para.c b/arch/powerpc/kernel/epapr_para.c
> index ea13cac..adee4f1 100644
> --- a/arch/powerpc/kernel/epapr_para.c
> +++ b/arch/powerpc/kernel/epapr_para.c
> @@ -20,6 +20,10 @@
> #include <linux/of.h>
> #include <asm/epapr_hcalls.h>
> #include <asm/cacheflush.h>
> +#include <asm/machdep.h>
> +
> +extern void epapr_ev_idle(void);
> +extern u32 epapr_ev_idle_start[];
> 
> bool epapr_para_enabled = false;
> 
> @@ -35,10 +39,17 @@ static int __init epapr_para_init(void)
> 
>    insts = of_get_property(hyper_node, "hcall-instructions", &len);
>    if (!(len % 4) && (len >= (4 * 4))) {
> -        for (i = 0; i < (len / 4); i++)
> +        for (i = 0; i < (len / 4); i++) {
>            epapr_hypercall_start[i] = insts[i];
> +            epapr_ev_idle_start[i] = insts[i];
> +        }
>        flush_icache_range((ulong)epapr_hypercall_start,
>                           (ulong)epapr_hypercall_start + len);
> +        flush_icache_range((ulong)epapr_ev_idle_start,
> +                           (ulong)epapr_ev_idle_start + len);
> +
> +        if (of_get_property(hyper_node, "has-idle", NULL))
> +            ppc_md.power_save = epapr_ev_idle;
> 
>        epapr_para_enabled = true;
>    }
> -- 
> 1.7.0.4
> 
> 
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