Re: [PATCH RESEND 08/15] ppc: spapr: Implement nested PAPR hcall - H_GUEST_CREATE

[Nicholas Piggin]

On Wed Sep 6, 2023 at 2:33 PM AEST, Harsh Prateek Bora wrote:
> This hcall is used by L1 to indicate to L0 that a new nested guest needs
> to be created and therefore necessary resource allocation shall be made.
> The L0 uses a hash table for nested guest specific resource management.
> This data structure is further utilized by other hcalls to operate on
> related members during entire life cycle of the nested guest.

Similar comment for changelog re detail. Detailed specification of API
and implementation could go in comments or documentation if useful.

>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>  hw/ppc/spapr_nested.c         | 75 +++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr_nested.h |  3 ++
>  2 files changed, 78 insertions(+)
>
> diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
> index 9af65f257f..09bbbfb341 100644
> --- a/hw/ppc/spapr_nested.c
> +++ b/hw/ppc/spapr_nested.c
> @@ -444,6 +444,80 @@ static target_ulong h_guest_set_capabilities(PowerPCCPU 
> *cpu,
>      return H_SUCCESS;
>  }
>  
> +static void
> +destroy_guest_helper(gpointer value)
> +{
> +    struct SpaprMachineStateNestedGuest *guest = value;
> +    g_free(guest);
> +}
> +
> +static target_ulong h_guest_create(PowerPCCPU *cpu,
> +                                   SpaprMachineState *spapr,
> +                                   target_ulong opcode,
> +                                   target_ulong *args)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    target_ulong flags = args[0];
> +    target_ulong continue_token = args[1];
> +    uint64_t lpid;
> +    int nguests = 0;
> +    struct SpaprMachineStateNestedGuest *guest;
> +
> +    if (flags) { /* don't handle any flags for now */
> +        return H_UNSUPPORTED_FLAG;
> +    }
> +
> +    if (continue_token != -1) {
> +        return H_P2;
> +    }
> +
> +    if (!spapr_get_cap(spapr, SPAPR_CAP_NESTED_PAPR)) {
> +        return H_FUNCTION;
> +    }
> +
> +    if (!spapr->nested.capabilities_set) {
> +        return H_STATE;
> +    }
> +
> +    if (!spapr->nested.guests) {
> +        spapr->nested.lpid_max = NESTED_GUEST_MAX;
> +        spapr->nested.guests = g_hash_table_new_full(NULL,
> +                                                     NULL,
> +                                                     NULL,
> +                                                     destroy_guest_helper);

Is lpid_max only used by create? Probably no need to have it in spapr
then->nested then. Also, do we even need to have a limit?

> +    }
> +
> +    nguests = g_hash_table_size(spapr->nested.guests);
> +
> +    if (nguests == spapr->nested.lpid_max) {
> +        return H_NO_MEM;
> +    }
> +
> +    /* Lookup for available lpid */
> +    for (lpid = 1; lpid < spapr->nested.lpid_max; lpid++) {

PAPR API calls it "guest ID" I think. Should change all references to
lpid to that.

> +        if (!(g_hash_table_lookup(spapr->nested.guests,
> +                                  GINT_TO_POINTER(lpid)))) {
> +            break;
> +        }
> +    }
> +    if (lpid == spapr->nested.lpid_max) {
> +        return H_NO_MEM;
> +    }
> +
> +    guest = g_try_new0(struct SpaprMachineStateNestedGuest, 1);
> +    if (!guest) {
> +        return H_NO_MEM;
> +    }
> +
> +    guest->pvr_logical = spapr->nested.pvr_base;
> +
> +    g_hash_table_insert(spapr->nested.guests, GINT_TO_POINTER(lpid), guest);
> +    printf("%s: lpid: %lu (MAX: %i)\n", __func__, lpid, 
> spapr->nested.lpid_max);

Remove printf.

> +
> +    env->gpr[4] = lpid;
> +    return H_SUCCESS;
> +}
> +
>  void spapr_register_nested(void)
>  {
>      spapr_register_hypercall(KVMPPC_H_SET_PARTITION_TABLE, h_set_ptbl);
> @@ -456,6 +530,7 @@ 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);
> +    spapr_register_hypercall(H_GUEST_CREATE          , h_guest_create);
>  }
>  
>  #else
> diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
> index a7996251cb..7841027df8 100644
> --- a/include/hw/ppc/spapr_nested.h
> +++ b/include/hw/ppc/spapr_nested.h
> @@ -197,6 +197,9 @@
>  #define H_GUEST_CAP_P9_MODE_BMAP    1
>  #define H_GUEST_CAP_P10_MODE_BMAP   2
>  
> +/* Nested PAPR API macros */
> +#define NESTED_GUEST_MAX 4096

Prefix with PAPR_?

Thanks,
Nick

> +
>  typedef struct SpaprMachineStateNestedGuest {
>      unsigned long vcpus;
>      struct SpaprMachineStateNestedGuestVcpu *vcpu;