On Tue, Jul 16, 2019 at 12:47:24PM +1000, Nicholas Piggin wrote:
> This does not do directed yielding and is not quite as strict as PAPR
> specifies in terms of precise dispatch behaviour. This generally will
> mean suboptimal performance, rather than guest misbehaviour. Linux
> does not rely on exact dispatch behaviour.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> hw/ppc/spapr_hcall.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 8b208ab259..28d58113be 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1069,6 +1069,53 @@ static target_ulong h_cede(PowerPCCPU *cpu,
> SpaprMachineState *spapr,
> return H_SUCCESS;
> }
>
> +static target_ulong h_confer(PowerPCCPU *cpu, SpaprMachineState *spapr,
> + target_ulong opcode, target_ulong *args)
> +{
> + target_long target = args[0];
> + uint32_t dispatch = args[1];
> + PowerPCCPU *target_cpu = spapr_find_cpu(target);
> + CPUState *target_cs = CPU(target_cpu);
> + CPUState *cs = CPU(cpu);
> + SpaprCpuState *spapr_cpu;
> +
> + /*
> + * This does not do a targeted yield or confer, but check the parameter
> + * anyway. -1 means confer to all/any other CPUs.
> + */
> + if (target != -1 && !target_cs) {
> + return H_PARAMETER;
> + }
Should we return an error if a targeted yield is attempted, rather
than pretend we've done it?
> +
> + spapr_cpu = spapr_cpu_state(target_cpu);
> +
> + /*
> + * PAPR specifies waiting until proded in this case, without dispatch
s/proded/prodded/
> + * counter check.
> + */
> + if (cpu == target_cpu) {
> + if (spapr_cpu->prod) {
> + spapr_cpu->prod = false;
> + return H_SUCCESS;
> + }
> +
> + cs->halted = 1;
> + cs->exception_index = EXCP_HALTED;
> + cs->exit_request = 1;
Now that we're using this sequence in a bunch of places, I wonder if
we want a little helper function.
> +
> + return H_SUCCESS;
> + }
> +
> + if (spapr_cpu->dispatch_counter != dispatch || (dispatch & 1) == 0) {
> + return H_SUCCESS;
> + }
> +
> + cs->exception_index = EXCP_YIELD;
> + cpu_loop_exit(cs);
> +
> + return H_SUCCESS;
> +}
> +
> static target_ulong h_prod(PowerPCCPU *cpu, SpaprMachineState *spapr,
> target_ulong opcode, target_ulong *args)
> {
> @@ -1909,6 +1956,7 @@ static void hypercall_register_types(void)
> /* hcall-splpar */
> spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa);
> spapr_register_hypercall(H_CEDE, h_cede);
> + spapr_register_hypercall(H_CONFER, h_confer);
> spapr_register_hypercall(H_PROD, h_prod);
>
> spapr_register_hypercall(H_SIGNAL_SYS_RESET, h_signal_sys_reset);
--
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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