Re: [Qemu-devel] [PATCH v4 2/2] target/ppc: move POWER9 DD1 workaround to init_proc_POWER9()

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jul 04, 2017 at 01:15:00PM +0200, Greg Kurz wrote:
> On Tue,  4 Jul 2017 13:01:26 +0200
> Laurent Vivier <lvivier@redhat.com> wrote:
> 
> > Commit 5f3066d ("target/ppc: Allow workarounds for POWER9 DD1")
> > disables compatibility mode for POWER9 DD1 to allow to
> > boot on POWER9 DD1 host with KVM.
> > 
> > As the workaround has been added in kvmppc_host_cpu_class_init(),
> > it applies only on CPU created with "-cpu host".
> > As we want to be able to use also "-cpu POWER9" on a POWER9 DD1
> > host, this patch moves the workaround from kvmppc_host_cpu_class_init()
> > to init_proc_POWER9().
> > 
> 
> As with ppc_cpu_initfn() in your previous version, init_proc_POWER9() is
> called for every CPU instance.. ie, all CPU will adjust the @pcr_supported
> class attribute...

Ah.. yeah.. I didn't notice that before.  That's definitely not right.

> What about moving the workaround to ppc_POWER9_cpu_family_class_init()
> instead ? This would just require to expose mfpvr() in some header.

Yeah, as someone else pointed out using the host PVR is also
definitely not right (unless you're in a function specifically
connected to the host cpu class).

> 
> --- a/target/ppc/translate_init.c
> +++ b/target/ppc/translate_init.c
> @@ -8913,8 +8913,10 @@ POWERPC_FAMILY(POWER9)(ObjectClass *oc, void *data)
>      dc->props = powerpc_servercpu_properties;
>      pcc->pvr_match = ppc_pvr_match_power9;
>      pcc->pcr_mask = PCR_COMPAT_2_05 | PCR_COMPAT_2_06 | PCR_COMPAT_2_07;
> -    pcc->pcr_supported = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 |
> -                         PCR_COMPAT_2_05;
> +    if (!kvm_enabled() || (mfpvr() & 0xffffff00) != CPU_POWERPC_POWER9_DD1) {
> +        pcc->pcr_supported = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 |
> +                             PCR_COMPAT_2_06 | PCR_COMPAT_2_05;
> +    }
>      pcc->init_proc = init_proc_POWER9;
>      pcc->check_pow = check_pow_nocheck;
>      cc->has_work = cpu_has_work_POWER9;
> 
> > Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> > ---
> >  target/ppc/kvm.c            | 11 -----------
> >  target/ppc/translate_init.c | 15 ++++++++++++++-
> >  2 files changed, 14 insertions(+), 12 deletions(-)
> > 
> > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> > index f2f7c53..9d76817 100644
> > --- a/target/ppc/kvm.c
> > +++ b/target/ppc/kvm.c
> > @@ -2381,17 +2381,6 @@ static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data)
> >  
> >  #if defined(TARGET_PPC64)
> >      pcc->radix_page_info = kvm_get_radix_page_info();
> > -
> > -    if ((pcc->pvr & 0xffffff00) == CPU_POWERPC_POWER9_DD1) {
> > -        /*
> > -         * POWER9 DD1 has some bugs which make it not really ISA 3.00
> > -         * compliant.  More importantly, advertising ISA 3.00
> > -         * architected mode may prevent guests from activating
> > -         * necessary DD1 workarounds.
> > -         */
> > -        pcc->pcr_supported &= ~(PCR_COMPAT_3_00 | PCR_COMPAT_2_07
> > -                                | PCR_COMPAT_2_06 | PCR_COMPAT_2_05);
> > -    }
> >  #endif /* defined(TARGET_PPC64) */
> >  }
> >  
> > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> > index 783bf98..a41fe66 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -8811,6 +8811,8 @@ static struct ppc_radix_page_info POWER9_radix_page_info = {
> >  
> >  static void init_proc_POWER9(CPUPPCState *env)
> >  {
> > +    PowerPCCPU *cpu = ppc_env_get_cpu(env);
> > +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> >      /* Common Registers */
> >      init_proc_book3s_common(env);
> >      gen_spr_book3s_207_dbg(env);
> > @@ -8848,7 +8850,18 @@ static void init_proc_POWER9(CPUPPCState *env)
> >  
> >      /* Allocate hardware IRQ controller */
> >      init_excp_POWER8(env);
> > -    ppcPOWER7_irq_init(ppc_env_get_cpu(env));
> > +    ppcPOWER7_irq_init(cpu);
> > +
> > +    if ((pcc->pvr & 0xffffff00) == CPU_POWERPC_POWER9_DD1) {
> > +        /*
> > +         * POWER9 DD1 has some bugs which make it not really ISA 3.00
> > +         * compliant.  More importantly, advertising ISA 3.00
> > +         * architected mode may prevent guests from activating
> > +         * necessary DD1 workarounds.
> > +         */
> > +        pcc->pcr_supported &= ~(PCR_COMPAT_3_00 | PCR_COMPAT_2_07
> > +                                | PCR_COMPAT_2_06 | PCR_COMPAT_2_05);
> > +    }
> >  }
> >  
> >  static bool ppc_pvr_match_power9(PowerPCCPUClass *pcc, uint32_t pvr)
> 



-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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