[PATCH v5 3/4] KVM: PPC: epapr: install ev_idle hcall for e500 guest

[Liu Yu-B13201]

> -----Original Message-----
> From: tiejun.chen [mailto:tiejun.chen at windriver.com]
> Sent: Tuesday, February 21, 2012 6:54 PM
> To: Liu Yu-B13201
> Cc: agraf at suse.de; kvm-ppc at vger.kernel.org; kvm at vger.kernel.org;
> linuxppc-dev at ozlabs.org; Wood Scott-B07421
> Subject: Re: [PATCH v5 3/4] KVM: PPC: epapr: install ev_idle hcall for
> e500 guest
> 
> Liu Yu wrote:
> > If the guest hypervisor node contains "has-idle" property.
> >
> > Signed-off-by: Liu Yu <yu.liu at freescale.com>
> > ---
> > v5: no change
> >
> >  arch/powerpc/kernel/epapr_hcalls.S   |   29
> +++++++++++++++++++++++++++++
> >  arch/powerpc/kernel/epapr_paravirt.c |   11 ++++++++++-
> >  2 files changed, 39 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/epapr_hcalls.S
> > b/arch/powerpc/kernel/epapr_hcalls.S
> > index 697b390..72fa234 100644
> > --- a/arch/powerpc/kernel/epapr_hcalls.S
> > +++ b/arch/powerpc/kernel/epapr_hcalls.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
> 
> Why not use 'EV_IDLE' directly?
> 
> > +
> > +_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)
> 
> And could this line be simplified as something like this:
> 
> LOAD_REG_IMMEDIATE(r11, EV_HCALL_TOKEN(EV_IDLE))
> 
> If so, even we can remove the previous HC_VENDOR_EPAPR definition as well.
> 

Because the epapr_hcalls.h contains C functions,
so it cannot be included by assembly code.

Thanks,
Yu