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Re: powerpc: Add an inline function to update HID0

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On Tuesday 04 August 2015 03:38 PM, 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@linux.vnet.ibm.com>
>> ---
>>  arch/powerpc/include/asm/kvm_ppc.h       | 11 +++++++++++
> Why is it in there? It's not KVM related per se.
>
> 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 ?

just to understand, Something like this will not do?

#define update_hid0(x)  __asm__ __volatile__(  
"sync\n"\                      
                                                "mtspr "
__stringify(SPRN_HID0)", %0\n"\
                                                "isync"::"r"(x));

Maddy

>
>> 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 ?
>
> cheers
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

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[PATCH] powerpc: Add an inline function to update HID0 "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> - 2015-08-04 10:40 +0200
  Re: powerpc: Add an inline function to update HID0 Michael Ellerman <mpe@ellerman.id.au> - 2015-08-04 12:10 +0200
    Re: powerpc: Add an inline function to update HID0 Gautham R Shenoy <ego@linux.vnet.ibm.com> - 2015-08-04 13:00 +0200
      [PATCH v2] powerpc: Add an inline function to update HID0 "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> - 2015-08-04 13:10 +0200
    Re: powerpc: Add an inline function to update HID0 Madhavan Srinivasan <maddy@linux.vnet.ibm.com> - 2015-08-04 16:10 +0200
      Re: powerpc: Add an inline function to update HID0 Michael Ellerman <mpe@ellerman.id.au> - 2015-08-05 04:10 +0200
    Re: powerpc: Add an inline function to update HID0 Segher Boessenkool <segher@kernel.crashing.org> - 2015-08-05 04:40 +0200
      Re: powerpc: Add an inline function to update HID0 Gautham R Shenoy <ego@linux.vnet.ibm.com> - 2015-08-05 09:00 +0200
        [PATCH v3] powerpc: Add an inline function to update POWER8 HID0 "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> - 2015-08-05 09:10 +0200
          Re: [PATCH v3] powerpc: Add an inline function to update POWER8 HID0 Sam Bobroff <sam.bobroff@au1.ibm.com> - 2015-08-14 07:00 +0200
          Re: [PATCH v3] powerpc: Add an inline function to update POWER8 HID0 Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> - 2015-08-14 11:10 +0200
          Re: [v3] powerpc: Add an inline function to update POWER8 HID0 Michael Ellerman <mpe@ellerman.id.au> - 2015-08-17 10:10 +0200
    Re: powerpc: Add an inline function to update HID0 Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-08-09 04:40 +0200

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