Re: [PATCH RESEND 07/15] ppc: spapr: Implement nested PAPR hcall - H_GUEST_SET_CAPABILITIES

[Harsh Prateek Bora]

On 9/7/23 07:39, Nicholas Piggin wrote:
> On Wed Sep 6, 2023 at 2:33 PM AEST, Harsh Prateek Bora wrote:
> > This patch implements nested PAPR hcall H_GUEST_SET_CAPABILITIES.
> > This is used by L1 to set capabilities of the nested guest being
> > created. The capabilities being set are subset of the capabilities
> > returned from the previous call to H_GUEST_GET_CAPABILITIES hcall.
> > Currently, it only supports P9/P10 capability check through PVR.
> >
> > Signed-off-by: Michael Neuling <mikey@neuling.org>
> > Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> > ---
> >   hw/ppc/spapr.c                |  1 +
> >   hw/ppc/spapr_nested.c         | 46 +++++++++++++++++++++++++++++++++++
> >   include/hw/ppc/spapr_nested.h |  3 +++
> >   3 files changed, 50 insertions(+)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index cbab7a825f..7c6f6ee25d 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -3443,6 +3443,7 @@ static void spapr_instance_init(Object *obj)
> >           "Host serial number to advertise in guest device tree");
> >       /* Nested */
> >       spapr->nested.api = 0;
> > +    spapr->nested.capabilities_set = false;
>
> I would actually think about moving spapr->nested init into
> spapr_nested.c.

Agree, moved.

> >   }
> >   
> >   static void spapr_machine_finalizefn(Object *obj)
> > diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
> > index 37f3a49be2..9af65f257f 100644
> > --- a/hw/ppc/spapr_nested.c
> > +++ b/hw/ppc/spapr_nested.c
> > @@ -399,6 +399,51 @@ static target_ulong h_guest_get_capabilities(PowerPCCPU 
> > *cpu,
> >       return H_SUCCESS;
> >   }
> >   
> > +static target_ulong h_guest_set_capabilities(PowerPCCPU *cpu,
> > +                                             SpaprMachineState *spapr,
> > +                                             target_ulong opcode,
> > +                                              target_ulong *args)
> > +{
> > +    CPUPPCState *env = &cpu->env;
> > +    target_ulong flags = args[0];
> > +    target_ulong capabilities = args[1];
> > +
> > +    if (flags) { /* don't handle any flags capabilities for now */
> > +        return H_PARAMETER;
> > +    }
> > +
> > +
>
> May need to do a pass over whitespace.

Sure, done.

> > +    /* isn't supported */
> > +    if (capabilities & H_GUEST_CAPABILITIES_COPY_MEM) {
> > +        env->gpr[4] = 0;
> > +        return H_P2;
> > +    }
> > +
> > +    if ((env->spr[SPR_PVR] & CPU_POWERPC_POWER_SERVER_MASK) ==
> > +        (CPU_POWERPC_POWER9_BASE)) {
> > +        /* We are a P9 */
> > +        if (!(capabilities & H_GUEST_CAPABILITIES_P9_MODE)) {
> > +            env->gpr[4] = 1;
> > +            return H_P2;
> > +        }
> > +    }
> > +
> > +    if ((env->spr[SPR_PVR] & CPU_POWERPC_POWER_SERVER_MASK) ==
> > +        (CPU_POWERPC_POWER10_BASE)) {
> > +        /* We are a P10 */
>
> The 2 comments above aren't helpful. Just remove them.

Sure, done.

> > +        if (!(capabilities & H_GUEST_CAPABILITIES_P10_MODE)) {
> > +            env->gpr[4] = 2;
> > +            return H_P2;
> > +        }
> > +    }
> > +
> > +    spapr->nested.capabilities_set = true;
>
> Is it okay to set twice? If not, add a check. If yes, remove
> capabilities_set until it's needed.

Thanks for pointing it out, adding a check as appropriate.

Thanks
Harsh

> > +
> > +    spapr->nested.pvr_base = env->spr[SPR_PVR];
> > +
> > +    return H_SUCCESS;
> > +}
> > +
> >   void spapr_register_nested(void)
> >   {
> >       spapr_register_hypercall(KVMPPC_H_SET_PARTITION_TABLE, h_set_ptbl);
> > @@ -410,6 +455,7 @@ void spapr_register_nested(void)
> >   void spapr_register_nested_phyp(void)
> >   {
> >       spapr_register_hypercall(H_GUEST_GET_CAPABILITIES, 
> > h_guest_get_capabilities);
> > +    spapr_register_hypercall(H_GUEST_SET_CAPABILITIES, 
> > h_guest_set_capabilities);
> >   }
> >   
> >   #else
> > diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
> > index ce198e9f70..a7996251cb 100644
> > --- a/include/hw/ppc/spapr_nested.h
> > +++ b/include/hw/ppc/spapr_nested.h
> > @@ -193,6 +193,9 @@
> >   #define H_GUEST_CAPABILITIES_COPY_MEM 0x8000000000000000
> >   #define H_GUEST_CAPABILITIES_P9_MODE  0x4000000000000000
> >   #define H_GUEST_CAPABILITIES_P10_MODE 0x2000000000000000
> > +#define H_GUEST_CAP_COPY_MEM_BMAP   0
> > +#define H_GUEST_CAP_P9_MODE_BMAP    1
> > +#define H_GUEST_CAP_P10_MODE_BMAP   2
> >   
> >   typedef struct SpaprMachineStateNestedGuest {
> >       unsigned long vcpus;