Re: [Qemu-devel] [PATCH for-2.10 2/2] target/ppc: Add stub implementation of the PSSCR

[Greg Kurz <groug@kaod.org>]

[-- Attachment #1: Type: text/plain, Size: 2774 bytes --]

On Tue, 8 Aug 2017 11:19:58 +0200
Cédric Le Goater <clg@kaod.org> wrote:

> On 08/08/2017 08:08 AM, David Gibson wrote:
> > The PSSCR register added in POWER9 controls certain power saving mode
> > behaviours.  Mostly, it's not relevant to TCG, however because qemu
> > doesn't know about it yet, it doesn't synchronize the state with KVM,
> > and thus it doesn't get migrated.
> > 
> > To fix that, this adds a minimal stub implementation of the register.
> > This isn't complete, even to the extent that an implementation is
> > possible in TCG, just enough to get migration working.  We need to
> > come back later and at least properly filter the various fields in the
> > register based on privilege level.  
> 
> yes a lot of the fields are only accessible to the hypervisor, and the 
> hypervisor also uses a different SPR number to access the PSSCR bits.
> 

This patch uses 0x357 (855) which is the SPR number for hypervisor state
access. But, yes, part of the register is also accessible in privileged
non-hypervisor state with SPR number 0x337 (823). This will have to be
covered later, but for now:

Reviewed-by: Greg Kurz <groug@kaod.org>

> Reviewed-by: Cédric Le Goater <clg@kaod.org>
> 
> C.
>   
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  target/ppc/cpu.h            | 1 +
> >  target/ppc/translate_init.c | 5 +++++
> >  2 files changed, 6 insertions(+)
> > 
> > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> > index f6e5413fad..46d3dd88f6 100644
> > --- a/target/ppc/cpu.h
> > +++ b/target/ppc/cpu.h
> > @@ -1771,6 +1771,7 @@ void ppc_compat_add_property(Object *obj, const char *name,
> >  #define SPR_IC                (0x350)
> >  #define SPR_VTB               (0x351)
> >  #define SPR_MMCRC             (0x353)
> > +#define SPR_PSSCR             (0x357)
> >  #define SPR_440_INV0          (0x370)
> >  #define SPR_440_INV1          (0x371)
> >  #define SPR_440_INV2          (0x372)
> > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> > index 94800cd29d..8fb407ed73 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -8846,6 +8846,11 @@ static void init_proc_POWER9(CPUPPCState *env)
> >                       spr_read_generic, spr_write_generic,
> >                       KVM_REG_PPC_TIDR, 0);
> >  
> > +    /* FIXME: Filter fields properly based on privilege level */
> > +    spr_register_kvm_hv(env, SPR_PSSCR, "PSSCR", NULL, NULL, NULL, NULL,
> > +                        spr_read_generic, spr_write_generic,
> > +                        KVM_REG_PPC_PSSCR, 0);
> > +
> >      /* env variables */
> >  #if !defined(CONFIG_USER_ONLY)
> >      env->slb_nr = 32;
> >   
> 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]