Re: [PATCH v5 06/14] spapr: nested: Introduce H_GUEST_[GET|SET]_CAPABILITIES hcalls.

[Nicholas Piggin]

On Fri Mar 8, 2024 at 9:19 PM AEST, Harsh Prateek Bora wrote:
> Introduce the nested PAPR hcalls:
>  - H_GUEST_GET_CAPABILITIES which is used to query the capabilities
>    of the API and the L2 guests it provides.
>  - H_GUEST_SET_CAPABILITIES which is used to set the Guest API
>    capabilities that the Host Partition supports and may use.
>
> [amachhiw: support for p9 compat mode and return register bug fixes]
>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> Signed-off-by: Amit Machhiwal <amachhiw@linux.vnet.ibm.com>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

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

> ---
>  include/hw/ppc/spapr.h        |   7 ++-
>  include/hw/ppc/spapr_nested.h |  12 ++++
>  hw/ppc/spapr_nested.c         | 112 ++++++++++++++++++++++++++++++++++
>  3 files changed, 130 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 0eb01ea6fd..2906d59137 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -364,6 +364,7 @@ struct SpaprMachineState {
>  #define H_NOOP            -63
>  #define H_UNSUPPORTED     -67
>  #define H_OVERLAP         -68
> +#define H_STATE           -75
>  #define H_UNSUPPORTED_FLAG -256
>  #define H_MULTI_THREADS_ACTIVE -9005
>  
> @@ -583,8 +584,10 @@ struct SpaprMachineState {
>  #define H_RPT_INVALIDATE        0x448
>  #define H_SCM_FLUSH             0x44C
>  #define H_WATCHDOG              0x45C
> +#define H_GUEST_GET_CAPABILITIES 0x460
> +#define H_GUEST_SET_CAPABILITIES 0x464
>  
> -#define MAX_HCALL_OPCODE        H_WATCHDOG
> +#define MAX_HCALL_OPCODE         H_GUEST_SET_CAPABILITIES
>  
>  /* The hcalls above are standardized in PAPR and implemented by pHyp
>   * as well.
> @@ -1033,5 +1036,7 @@ void spapr_watchdog_init(SpaprMachineState *spapr);
>  void spapr_register_nested_hv(void);
>  void spapr_unregister_nested_hv(void);
>  void spapr_nested_reset(SpaprMachineState *spapr);
> +void spapr_register_nested_papr(void);
> +void spapr_unregister_nested_papr(void);
>  
>  #endif /* HW_SPAPR_H */
> diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
> index bf3a7b8d89..73687e03e4 100644
> --- a/include/hw/ppc/spapr_nested.h
> +++ b/include/hw/ppc/spapr_nested.h
> @@ -7,8 +7,20 @@ typedef struct SpaprMachineStateNested {
>      uint64_t ptcr;
>      uint8_t api;
>  #define NESTED_API_KVM_HV  1
> +    bool capabilities_set;
> +    uint32_t pvr_base;
>  } SpaprMachineStateNested;
>  
> +/* Nested PAPR API related macros */
> +#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_VALID_MASK        (H_GUEST_CAPABILITIES_P10_MODE | \
> +                                       H_GUEST_CAPABILITIES_P9_MODE)
> +#define H_GUEST_CAP_COPY_MEM_BMAP     0
> +#define H_GUEST_CAP_P9_MODE_BMAP      1
> +#define H_GUEST_CAP_P10_MODE_BMAP     2
> +
>  /*
>   * Register state for entering a nested guest with H_ENTER_NESTED.
>   * New member must be added at the end.
> diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
> index 12fdbe2aba..601f669060 100644
> --- a/hw/ppc/spapr_nested.c
> +++ b/hw/ppc/spapr_nested.c
> @@ -7,6 +7,7 @@
>  #include "hw/ppc/spapr_cpu_core.h"
>  #include "hw/ppc/spapr_nested.h"
>  #include "mmu-book3s-v3.h"
> +#include "cpu-models.h"
>  
>  void spapr_nested_reset(SpaprMachineState *spapr)
>  {
> @@ -16,6 +17,7 @@ void spapr_nested_reset(SpaprMachineState *spapr)
>          spapr_register_nested_hv();
>      } else {
>          spapr->nested.api = 0;
> +        spapr->nested.capabilities_set = false;
>      }
>  }
>  
> @@ -432,6 +434,92 @@ void spapr_exit_nested(PowerPCCPU *cpu, int excp)
>      }
>  }
>  
> +static target_ulong h_guest_get_capabilities(PowerPCCPU *cpu,
> +                                             SpaprMachineState *spapr,
> +                                             target_ulong opcode,
> +                                             target_ulong *args)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    target_ulong flags = args[0];
> +
> +    if (flags) { /* don't handle any flags capabilities for now */
> +        return H_PARAMETER;
> +    }
> +
> +    /* P10 capabilities */
> +    if (ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_3_10, 0,
> +        spapr->max_compat_pvr)) {
> +        env->gpr[4] |= H_GUEST_CAPABILITIES_P10_MODE;
> +    }
> +
> +    /* P9 capabilities */
> +    if (ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_3_00, 0,
> +        spapr->max_compat_pvr)) {
> +        env->gpr[4] |= H_GUEST_CAPABILITIES_P9_MODE;
> +    }
> +
> +    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];
> +    env->gpr[4] = 0;
> +
> +    if (flags) { /* don't handle any flags capabilities for now */
> +        return H_PARAMETER;
> +    }
> +
> +    if (capabilities & H_GUEST_CAPABILITIES_COPY_MEM) {
> +        env->gpr[4] = 1;
> +        return H_P2; /* isn't supported */
> +    }
> +
> +    /* If there are no capabilities configured, set the R5 to the index of
> +     * the first supported Power Processor Mode
> +     */
> +    if (!capabilities) {
> +        env->gpr[4] = 1;
> +
> +        /* set R5 to the first supported Power Processor Mode */
> +        if(ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_3_10, 0,
> +                            spapr->max_compat_pvr)) {
> +            env->gpr[5] = H_GUEST_CAP_P10_MODE_BMAP;
> +        }
> +        else if (ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_3_00, 0,
> +                                  spapr->max_compat_pvr)) {
> +            env->gpr[5] = H_GUEST_CAP_P9_MODE_BMAP;
> +        }
> +
> +        return H_P2;
> +    }
> +
> +    /* If an invalid capability is set, R5 should contain the index of the
> +     * invalid capability bit
> +     */
> +    if (capabilities & ~H_GUEST_CAP_VALID_MASK) {
> +        env->gpr[4] = 1;
> +
> +        /* Set R5 to the index of the invalid capability */
> +        env->gpr[5] = 63 - ctz64(capabilities);
> +
> +        return H_P2;
> +    }
> +
> +    if (!spapr->nested.capabilities_set) {
> +        spapr->nested.capabilities_set = true;
> +        spapr->nested.pvr_base = env->spr[SPR_PVR];
> +        return H_SUCCESS;
> +    } else {
> +        return H_STATE;
> +    }
> +}
> +
>  void spapr_register_nested_hv(void)
>  {
>      spapr_register_hypercall(KVMPPC_H_SET_PARTITION_TABLE, h_set_ptbl);
> @@ -447,6 +535,19 @@ void spapr_unregister_nested_hv(void)
>      spapr_unregister_hypercall(KVMPPC_H_TLB_INVALIDATE);
>      spapr_unregister_hypercall(KVMPPC_H_COPY_TOFROM_GUEST);
>  }
> +
> +void spapr_register_nested_papr(void)
> +{
> +    spapr_register_hypercall(H_GUEST_GET_CAPABILITIES, 
> h_guest_get_capabilities);
> +    spapr_register_hypercall(H_GUEST_SET_CAPABILITIES, 
> h_guest_set_capabilities);
> +}
> +
> +void spapr_unregister_nested_papr(void)
> +{
> +    spapr_unregister_hypercall(H_GUEST_GET_CAPABILITIES);
> +    spapr_unregister_hypercall(H_GUEST_SET_CAPABILITIES);
> +}
> +
>  #else
>  void spapr_exit_nested(PowerPCCPU *cpu, int excp)
>  {
> @@ -468,4 +569,15 @@ bool spapr_get_pate_nested_hv(SpaprMachineState *spapr, 
> PowerPCCPU *cpu,
>  {
>      return false;
>  }
> +
> +void spapr_register_nested_papr(void)
> +{
> +    /* DO NOTHING */
> +}
> +
> +void spapr_unregister_nested_papr(void)
> +{
> +    /* DO NOTHING */
> +}
> +
>  #endif