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

[Harsh Prateek Bora <harshpb@linux.ibm.com>]

On 9/7/23 07:58, Nicholas Piggin wrote:
> 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.
> 
Sure, squashing guest create/delete together and updating commit log to 
be abstract as needed.

>>
>> 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?

Yes, as of now, it is being used only by create and doesnt need to part
of spapr->nested. We can simply use the macro for max guests. Keeping it
to emulate a finite resource model.
For all practical purposes, nested guests in an TCG emulated L0
shouldn't reach that 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.

Changing it to "guestid".

> 
>> +        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.
> 
Done.

>> +
>> +    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_?

Done.

Thanks
Harsh
> 
> Thanks,
> Nick
> 
>> +
>>   typedef struct SpaprMachineStateNestedGuest {
>>       unsigned long vcpus;
>>       struct SpaprMachineStateNestedGuestVcpu *vcpu;
>