Re: [PATCH v4 04/15] spapr: nested: keep nested-hv related code restricted to its API.

["Nicholas Piggin" <npiggin@gmail.com>]

On Tue Feb 20, 2024 at 6:35 PM AEST, Harsh Prateek Bora wrote:
> spapr_exit_nested and spapr_get_pate_nested_hv contains code which
> is specific to nested-hv API. Isolating code flows based on API
> helps extending it to be used with different API as well.
>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  include/hw/ppc/spapr_nested.h |  4 ++++
>  hw/ppc/spapr.c                |  7 ++++++-
>  hw/ppc/spapr_caps.c           |  1 +
>  hw/ppc/spapr_nested.c         | 27 ++++++++++++++++++++++++---
>  4 files changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
> index 2488ea98da..3f07c81c3d 100644
> --- a/include/hw/ppc/spapr_nested.h
> +++ b/include/hw/ppc/spapr_nested.h
> @@ -5,6 +5,8 @@
>  
>  typedef struct SpaprMachineStateNested {
>      uint64_t ptcr;
> +    uint8_t api;
> +#define NESTED_API_KVM_HV  1
>  } SpaprMachineStateNested;
>  
>  /*
> @@ -103,4 +105,6 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp);
>  typedef struct SpaprMachineState SpaprMachineState;
>  bool spapr_get_pate_nested_hv(SpaprMachineState *spapr, PowerPCCPU *cpu,
>                                target_ulong lpid, ppc_v3_pate_t *entry);
> +void spapr_nested_init(SpaprMachineState *spapr);
> +uint8_t spapr_nested_api(SpaprMachineState *spapr);
>  #endif /* HW_SPAPR_NESTED_H */
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 97b69c0e42..51a1be027a 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1376,7 +1376,11 @@ static bool spapr_get_pate(PPCVirtualHypervisor *vhyp, PowerPCCPU *cpu,
>          entry->dw1 = spapr->patb_entry;
>          return true;
>      } else {
> -        return spapr_get_pate_nested_hv(spapr, cpu, lpid, entry);
> +        assert(spapr_nested_api(spapr));
> +        if (spapr_nested_api(spapr) == NESTED_API_KVM_HV) {
> +            return spapr_get_pate_nested_hv(spapr, cpu, lpid, entry);
> +        }
> +        return false;
>      }
>  }
>  
> @@ -3443,6 +3447,7 @@ static void spapr_instance_init(Object *obj)
>          spapr_get_host_serial, spapr_set_host_serial);
>      object_property_set_description(obj, "host-serial",
>          "Host serial number to advertise in guest device tree");
> +    spapr_nested_init(spapr);

I would maybe make this init a reset instead, and then it could do
the hypercall unregistering as well? You could rework that part of
it into patch 1 (or reorder the patches).

Thanks,
Nick