[PATCH] KVM: PPC: add paravirt idle loop for 64-bit book E
Scott Wood
scottwood at freescale.com
Thu Jan 17 04:44:18 EST 2013
On 01/16/2013 11:21:24 AM, Stuart Yoder wrote:
> From: Stuart Yoder <stuart.yoder at freescale.com>
>
> loop was derived from book3e_idle()
>
> Signed-off-by: Stuart Yoder <stuart.yoder at freescale.com>
> ---
> arch/powerpc/kernel/epapr_hcalls.S | 63
> ++++++++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
>
> diff --git a/arch/powerpc/kernel/epapr_hcalls.S
> b/arch/powerpc/kernel/epapr_hcalls.S
> index 62c0dc2..6a46bfb 100644
> --- a/arch/powerpc/kernel/epapr_hcalls.S
> +++ b/arch/powerpc/kernel/epapr_hcalls.S
> @@ -17,6 +17,68 @@
> #include <asm/asm-compat.h>
> #include <asm/asm-offsets.h>
>
> +#ifdef CONFIG_PPC64
> +/* epapr_ev_idle() was derived from book3e_idle() */
> +_GLOBAL(epapr_ev_idle)
> + /* Save LR for later */
> + mflr r0
> + std r0,16(r1)
> +
> + /* Hard disable interrupts */
> + wrteei 0
> +
> + /* Now check if an interrupt came in while we were soft disabled
> + * since we may otherwise lose it (doorbells etc...).
> + */
> + lbz r3,PACAIRQHAPPENED(r13)
> + cmpwi cr0,r3,0
> + bnelr
> +
> + /* Now we are going to mark ourselves as soft and hard enabled
> in
> + * order to be able to take interrupts while asleep. We inform
> lockdep
> + * of that. We don't actually turn interrupts on just yet tho.
> + */
> +#ifdef CONFIG_TRACE_IRQFLAGS
> + stdu r1,-128(r1)
> + bl .trace_hardirqs_on
> + addi r1,r1,128
> +#endif
> + li r0,1
> + stb r0,PACASOFTIRQEN(r13)
> +
> + /* Interrupts will make use return to LR, so get something we
> want
> + * in there
> + */
> + bl 1f
> +
> + /* And return (interrupts are on) */
> + ld r0,16(r1)
> + mtlr r0
> + blr
> +
> +1: /* Let's set the _TLF_NAPPING flag so interrupts make us return
> + * to the right spot
> + */
> + CURRENT_THREAD_INFO(r11, r1)
> + ld r10,TI_LOCAL_FLAGS(r11)
> + ori r10,r10,_TLF_NAPPING
> + std r10,TI_LOCAL_FLAGS(r11)
> +
> + /* We can now re-enable hard interrupts and go to sleep */
> + wrteei 1
> +idle_loop:
> + LOAD_REG_IMMEDIATE(r11, EV_HCALL_TOKEN(EV_IDLE))
> +
> +.global epapr_ev_idle_start
> +epapr_ev_idle_start:
> + li r3, -1
> + nop
> + nop
> + nop
> + b idle_loop
> +
We should probably do this as an assembler macro, so we can have one
instance of it that gets instantiated for both "wait" and "ev_idle".
-Scott
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