Re: [Qemu-devel] [PATCH 15/17] ppc: Add dummy POWER8 MPPR register

["Cédric Le Goater" <clg@fr.ibm.com>]

On 03/16/2016 07:17 AM, Thomas Huth wrote:
> On 16.03.2016 02:14, David Gibson wrote:
>> On Mon, Mar 14, 2016 at 05:56:38PM +0100, Cédric Le Goater wrote:
>>> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>>
>>> Controls the micropartition prefetch, this is pretty much meaningless
>>> in full emulation (used for priming the caches on real HW).
>>>
>>> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>
>> So, this is readable with HV=0, so technically a fix even for non-HV
>> machines.  I'm guessing it's not actually read in practice outside the
>> HV, though.  Not sure if this should go in 2.6 or 2.7.
> 
> Patch looks simple (i.e. without risk) enough to be fine for 2.6, I think.
> But looking at this again, I wonder why there is no KVM_REG_PPC_*
> definition for this register, so that it could be sync'ed with the
> kernel, too? Is that on purpose or is it just missing by accident?

The spr was reverted : 

	http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=23316316c1af

I should have checked that. I guess we don't want to keep the patch for
2.6 then.

C.

>  Thomas
> 
>>> ---
>>>  target-ppc/cpu.h            |  1 +
>>>  target-ppc/translate_init.c | 13 +++++++++++++
>>>  2 files changed, 14 insertions(+)
>>>
>>> diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
>>> index 81a3e6b5ed29..5203cc6a3bfb 100644
>>> --- a/target-ppc/cpu.h
>>> +++ b/target-ppc/cpu.h
>>> @@ -1398,6 +1398,7 @@ static inline int cpu_mmu_index (CPUPPCState *env, bool ifetch)
>>>  #define SPR_DHDES             (0x0B1)
>>>  #define SPR_DPDES             (0x0B0)
>>>  #define SPR_DAWR              (0x0B4)
>>> +#define SPR_MPPR              (0x0B8)
>>>  #define SPR_RPR               (0x0BA)
>>>  #define SPR_DAWRX             (0x0BC)
>>>  #define SPR_HFSCR             (0x0BE)
>>> diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
>>> index 28a9c2e73156..cfb1bc088950 100644
>>> --- a/target-ppc/translate_init.c
>>> +++ b/target-ppc/translate_init.c
>>> @@ -8161,6 +8161,18 @@ static void gen_spr_power8_ic(CPUPPCState *env)
>>>  #endif
>>>  }
>>>  
>>> +static void gen_spr_power8_book4(CPUPPCState *env)
>>> +{
>>> +    /* Add a number of P8 book4 registers */
>>> +#if !defined(CONFIG_USER_ONLY)
>>> +    spr_register_hv(env, SPR_MPPR, "MPPR",
>>> +                    SPR_NOACCESS, SPR_NOACCESS,
>>> +                    &spr_read_generic, SPR_NOACCESS,
>>> +                    &spr_read_generic, &spr_write_generic,
>>> +                    0);
>>> +#endif
>>> +}
>>> +
>>>  static void init_proc_book3s_64(CPUPPCState *env, int version)
>>>  {
>>>      gen_spr_ne_601(env);
>>> @@ -8216,6 +8228,7 @@ static void init_proc_book3s_64(CPUPPCState *env, int version)
>>>          gen_spr_power8_rpr(env);
>>>          gen_spr_power8_dbell(env);
>>>          gen_spr_power8_ic(env);
>>> +        gen_spr_power8_book4(env);
>>>      }
>>>      if (version < BOOK3S_CPU_POWER8) {
>>>          gen_spr_book3s_dbg(env);
>>
> 
>