Re: [Qemu-devel] [QEMU-PPC] [PATCH V3 6/6] target/ppc/spapr: Add H-Call H_GET_CPU_CHARACTERISTICS

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Jan 15, 2018 at 05:32:35PM +1100, Suraj Jitindar Singh wrote:
> The new H-Call H_GET_CPU_CHARACTERISTICS is used by the guest to query
> behaviours and available characteristics of the cpu.
> 
> Implement the handler for this new H-Call which formulates its response
> based on the setting of the spapr_caps cap-cfpc, cap-sbbc and cap-ibs.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> ---
>  hw/ppc/spapr_hcall.c   | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |  1 +
>  2 files changed, 67 insertions(+)
> 
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 51eba52e86..a693d3b852 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1654,6 +1654,69 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
>      return H_SUCCESS;
>  }
>  
> +static target_ulong h_get_cpu_characteristics(PowerPCCPU *cpu,
> +                                              sPAPRMachineState *spapr,
> +                                              target_ulong opcode,
> +                                              target_ulong *args)
> +{
> +    uint64_t characteristics = H_CPU_CHAR_HON_BRANCH_HINTS &
> +			       ~H_CPU_CHAR_THR_RECONF_TRIG;
> +    uint64_t behaviour = H_CPU_BEHAV_FAVOUR_SECURITY;
> +    uint8_t safe_cache = spapr_get_cap(spapr, SPAPR_CAP_CFPC);
> +    uint8_t safe_bounds_check = spapr_get_cap(spapr, SPAPR_CAP_SBBC);
> +    uint8_t safe_indirect_branch = spapr_get_cap(spapr, SPAPR_CAP_IBS);
> +
> +    switch (safe_cache) {
> +    case SPAPR_CAP_WORKAROUND:
> +        characteristics |= H_CPU_CHAR_L1D_FLUSH_ORI30;
> +        characteristics |= H_CPU_CHAR_L1D_FLUSH_TRIG2;
> +        characteristics |= H_CPU_CHAR_L1D_THREAD_PRIV;
> +        behaviour |= H_CPU_BEHAV_L1D_FLUSH_PR;
> +        break;
> +    case SPAPR_CAP_FIXED:
> +        break;
> +    default: /* broken */
> +        if (safe_cache != SPAPR_CAP_BROKEN) {

I think you just assert() for this.  The only way these could get a
different value is if there's a bug elsewhere.

> +            error_report("Invalid value for cap-cfpc (%d), assuming broken",
> +                         safe_cache);
> +        }
> +        behaviour |= H_CPU_BEHAV_L1D_FLUSH_PR;
> +        break;
> +    }
> +
> +    switch (safe_bounds_check) {
> +    case SPAPR_CAP_WORKAROUND:
> +        characteristics |= H_CPU_CHAR_SPEC_BAR_ORI31;
> +        behaviour |= H_CPU_BEHAV_BNDS_CHK_SPEC_BAR;
> +        break;
> +    case SPAPR_CAP_FIXED:
> +        break;
> +    default: /* broken */
> +        if (safe_bounds_check != SPAPR_CAP_BROKEN) {
> +            error_report("Invalid value for cap-sbbc (%d), assuming broken",
> +                         safe_bounds_check);
> +        }
> +        behaviour |= H_CPU_BEHAV_BNDS_CHK_SPEC_BAR;
> +        break;
> +    }
> +
> +    switch (safe_indirect_branch) {
> +    case SPAPR_CAP_FIXED:
> +        characteristics |= H_CPU_CHAR_BCCTRL_SERIALISED;
> +    default: /* broken */
> +        if (safe_indirect_branch != SPAPR_CAP_BROKEN) {
> +            error_report("Invalid value for cap-ibs (%d), assuming broken",
> +                         safe_indirect_branch);
> +        }
> +        break;
> +    }
> +
> +    args[0] = characteristics;
> +    args[1] = behaviour;
> +
> +    return H_SUCCESS;
> +}
> +
>  static spapr_hcall_fn papr_hypercall_table[(MAX_HCALL_OPCODE / 4) + 1];
>  static spapr_hcall_fn kvmppc_hypercall_table[KVMPPC_HCALL_MAX - KVMPPC_HCALL_BASE + 1];
>  
> @@ -1733,6 +1796,9 @@ static void hypercall_register_types(void)
>      spapr_register_hypercall(H_INVALIDATE_PID, h_invalidate_pid);
>      spapr_register_hypercall(H_REGISTER_PROC_TBL, h_register_process_table);
>  
> +    /* hcall-get-cpu-characteristics */
> +    spapr_register_hypercall(H_GET_CPU_CHARACTERISTICS, h_get_cpu_characteristics);
> +
>      /* "debugger" hcalls (also used by SLOF). Note: We do -not- differenciate
>       * here between the "CI" and the "CACHE" variants, they will use whatever
>       * mapping attributes qemu is using. When using KVM, the kernel will
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 549d7a4134..62c077ac20 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -404,6 +404,7 @@ struct sPAPRMachineState {
>  #define H_GET_HCA_INFO          0x1B8
>  #define H_GET_PERF_COUNT        0x1BC
>  #define H_MANAGE_TRACE          0x1C0
> +#define H_GET_CPU_CHARACTERISTICS 0x1C8
>  #define H_FREE_LOGICAL_LAN_BUFFER 0x1D4
>  #define H_QUERY_INT_STATE       0x1E4
>  #define H_POLL_PENDING          0x1D8

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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