Re: [PATCH v5 08/14] spapr: nested: Introduce H_GUEST_CREATE_VCPU hcall.

[Nicholas Piggin]

On Fri Mar 8, 2024 at 9:19 PM AEST, Harsh Prateek Bora wrote:
> Introduce the nested PAPR hcall H_GUEST_CREATE_VCPU which is used to
> create and initialize the specified VCPU resource for the previously
> created guest. Each guest can have multiple VCPUs upto max 2048.
> All VCPUs for a guest gets deallocated on guest delete.
>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

> ---
>  include/hw/ppc/spapr.h        |  2 ++
>  include/hw/ppc/spapr_nested.h |  8 +++++
>  hw/ppc/spapr_nested.c         | 61 +++++++++++++++++++++++++++++++++++
>  3 files changed, 71 insertions(+)
>
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 13416fc3d7..070135793a 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -365,6 +365,7 @@ struct SpaprMachineState {
>  #define H_UNSUPPORTED     -67
>  #define H_OVERLAP         -68
>  #define H_STATE           -75
> +#define H_IN_USE          -77
>  #define H_UNSUPPORTED_FLAG -256
>  #define H_MULTI_THREADS_ACTIVE -9005
>  
> @@ -587,6 +588,7 @@ struct SpaprMachineState {
>  #define H_GUEST_GET_CAPABILITIES 0x460
>  #define H_GUEST_SET_CAPABILITIES 0x464
>  #define H_GUEST_CREATE           0x470
> +#define H_GUEST_CREATE_VCPU      0x474
>  #define H_GUEST_DELETE           0x488
>  
>  #define MAX_HCALL_OPCODE         H_GUEST_DELETE
> diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
> index 56d43e540b..2ac3076fac 100644
> --- a/include/hw/ppc/spapr_nested.h
> +++ b/include/hw/ppc/spapr_nested.h
> @@ -14,6 +14,8 @@ typedef struct SpaprMachineStateNested {
>  
>  typedef struct SpaprMachineStateNestedGuest {
>      uint32_t pvr_logical;
> +    unsigned long nr_vcpus;
> +    struct SpaprMachineStateNestedGuestVcpu *vcpus;
>  } SpaprMachineStateNestedGuest;
>  
>  /* Nested PAPR API related macros */
> @@ -27,6 +29,7 @@ typedef struct SpaprMachineStateNestedGuest {
>  #define H_GUEST_CAP_P10_MODE_BMAP     2
>  #define PAPR_NESTED_GUEST_MAX         4096
>  #define H_GUEST_DELETE_ALL_FLAG       0x8000000000000000ULL
> +#define PAPR_NESTED_GUEST_VCPU_MAX    2048
>  
>  /*
>   * Register state for entering a nested guest with H_ENTER_NESTED.
> @@ -120,6 +123,11 @@ struct nested_ppc_state {
>      int64_t tb_offset;
>  };
>  
> +typedef struct SpaprMachineStateNestedGuestVcpu {
> +    bool enabled;
> +    struct nested_ppc_state state;
> +} SpaprMachineStateNestedGuestVcpu;
> +
>  void spapr_exit_nested(PowerPCCPU *cpu, int excp);
>  typedef struct SpaprMachineState SpaprMachineState;
>  bool spapr_get_pate_nested_hv(SpaprMachineState *spapr, PowerPCCPU *cpu,
> diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
> index 13674c0857..4c0e2e91e1 100644
> --- a/hw/ppc/spapr_nested.c
> +++ b/hw/ppc/spapr_nested.c
> @@ -8,6 +8,7 @@
>  #include "hw/ppc/spapr_nested.h"
>  #include "mmu-book3s-v3.h"
>  #include "cpu-models.h"
> +#include "qemu/log.h"
>  
>  void spapr_nested_reset(SpaprMachineState *spapr)
>  {
> @@ -434,6 +435,16 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp)
>      }
>  }
>  
> +static
> +SpaprMachineStateNestedGuest *spapr_get_nested_guest(SpaprMachineState 
> *spapr,
> +                                                     target_ulong guestid)
> +{
> +    SpaprMachineStateNestedGuest *guest;
> +
> +    guest = g_hash_table_lookup(spapr->nested.guests, 
> GINT_TO_POINTER(guestid));
> +    return guest;
> +}
> +
>  static target_ulong h_guest_get_capabilities(PowerPCCPU *cpu,
>                                               SpaprMachineState *spapr,
>                                               target_ulong opcode,
> @@ -524,6 +535,7 @@ static void
>  destroy_guest_helper(gpointer value)
>  {
>      struct SpaprMachineStateNestedGuest *guest = value;
> +    g_free(guest->vcpus);
>      g_free(guest);
>  }
>  
> @@ -619,6 +631,53 @@ static target_ulong h_guest_delete(PowerPCCPU *cpu,
>      return H_SUCCESS;
>  }
>  
> +static target_ulong h_guest_create_vcpu(PowerPCCPU *cpu,
> +                                        SpaprMachineState *spapr,
> +                                        target_ulong opcode,
> +                                        target_ulong *args)
> +{
> +    target_ulong flags = args[0];
> +    target_ulong guestid = args[1];
> +    target_ulong vcpuid = args[2];
> +    SpaprMachineStateNestedGuest *guest;
> +
> +    if (flags) { /* don't handle any flags for now */
> +        return H_UNSUPPORTED_FLAG;
> +    }
> +
> +    guest = spapr_get_nested_guest(spapr, guestid);
> +    if (!guest) {
> +        return H_P2;
> +    }
> +
> +    if (vcpuid < guest->nr_vcpus) {
> +        qemu_log_mask(LOG_UNIMP, "vcpuid %ld already in use, return.", 
> vcpuid);
> +        return H_IN_USE;
> +    }
> +    /* linear vcpuid allocation only */
> +    assert(vcpuid == guest->nr_vcpus);
> +
> +    if (guest->nr_vcpus >= PAPR_NESTED_GUEST_VCPU_MAX) {
> +        return H_P3;
> +    }
> +
> +    SpaprMachineStateNestedGuestVcpu *vcpus, *curr_vcpu;
> +    vcpus = g_try_renew(struct SpaprMachineStateNestedGuestVcpu,
> +                        guest->vcpus,
> +                        guest->nr_vcpus + 1);
> +    if (!vcpus) {
> +        return H_NO_MEM;
> +    }
> +    guest->vcpus = vcpus;
> +    curr_vcpu = &vcpus[guest->nr_vcpus];
> +    memset(curr_vcpu, 0, sizeof(SpaprMachineStateNestedGuestVcpu));
> +
> +    curr_vcpu->enabled = true;
> +    guest->nr_vcpus++;
> +
> +    return H_SUCCESS;
> +}
> +
>  void spapr_register_nested_hv(void)
>  {
>      spapr_register_hypercall(KVMPPC_H_SET_PARTITION_TABLE, h_set_ptbl);
> @@ -641,6 +700,7 @@ void spapr_register_nested_papr(void)
>      spapr_register_hypercall(H_GUEST_SET_CAPABILITIES, 
> h_guest_set_capabilities);
>      spapr_register_hypercall(H_GUEST_CREATE          , h_guest_create);
>      spapr_register_hypercall(H_GUEST_DELETE          , h_guest_delete);
> +    spapr_register_hypercall(H_GUEST_CREATE_VCPU     , h_guest_create_vcpu);
>  }
>  
>  void spapr_unregister_nested_papr(void)
> @@ -649,6 +709,7 @@ void spapr_unregister_nested_papr(void)
>      spapr_unregister_hypercall(H_GUEST_SET_CAPABILITIES);
>      spapr_unregister_hypercall(H_GUEST_CREATE);
>      spapr_unregister_hypercall(H_GUEST_DELETE);
> +    spapr_unregister_hypercall(H_GUEST_CREATE_VCPU);
>  }
>  
>  #else