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Date: Tue, 4 Aug 2015 16:27:47 +0530 From: Gautham R Shenoy <ego@...ux.vnet.ibm.com> To: Michael Ellerman <mpe@...erman.id.au> Cc: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>, Paul Mackerras <paulus@...ba.org>, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, mikey@...ling.org Subject: Re: powerpc: Add an inline function to update HID0 Hi Michael, On Tue, Aug 04, 2015 at 08:08:58PM +1000, Michael Ellerman wrote: > On Tue, 2015-04-08 at 08:30:58 UTC, "Gautham R. Shenoy" wrote: > > Section 3.7 of Version 1.2 of the Power8 Processor User's Manual > > prescribes that updates to HID0 be preceded by a SYNC instruction and > > followed by an ISYNC instruction (Page 91). > > > > Create a function name update_hid0() which follows this recipe and > > invoke it from the static split core path. > > > > Signed-off-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com> > > --- > > arch/powerpc/include/asm/kvm_ppc.h | 11 +++++++++++ > > Why is it in there? It's not KVM related per se. Ok. Will fix this. > > Where should it go? I think reg.h would be best, ideally near the definition > for HID0, though that's probably not possible because of ASSEMBLY requirements. > So at the bottom of reg.h ? > > > diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h > > index c6ef05b..325f1d6 100644 > > --- a/arch/powerpc/include/asm/kvm_ppc.h > > +++ b/arch/powerpc/include/asm/kvm_ppc.h > > @@ -685,4 +685,15 @@ static inline ulong kvmppc_get_ea_indexed(struct kvm_vcpu *vcpu, int ra, int rb) > > > > extern void xics_wake_cpu(int cpu); > > > > +static inline void update_hid0(unsigned long hid0) > > +{ > > + /* > > + * The HID0 update should at the very least be preceded by a > > + * a SYNC instruction followed by an ISYNC instruction > > + */ > > + mb(); > > + mtspr(SPRN_HID0, hid0); > > + isync(); > > That's going to turn into three separate inline asm blocks, which is maybe a > bit unfortunate. Have you checked the generated code is what we want, ie. just > sync, mtspr, isync ? > Yes, the objdump of subcore.o shows exactly these three instructions: 7c 00 04 ac sync 7c 70 fb a6 mtspr 1008,r3 4c 00 01 2c isync > cheers > -- Thanks and Regards gautham. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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