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Re: [Qemu-ppc] [PATCH v5 4/4] spapr: Implement H_JOIN
From: |
Nicholas Piggin |
Subject: |
Re: [Qemu-ppc] [PATCH v5 4/4] spapr: Implement H_JOIN |
Date: |
Thu, 18 Jul 2019 12:25:23 +1000 |
User-agent: |
astroid/0.14.0 (https://github.com/astroidmail/astroid) |
Greg Kurz's on July 18, 2019 3:30 am:
> On Wed, 17 Jul 2019 15:39:52 +1000
> Nicholas Piggin <address@hidden> wrote:
>
>> This has been useful to modify and test the Linux pseries suspend
>> code but it requires modification to the guest to call it (due to
>> being gated by other unimplemented features). It is not otherwise
>> used by Linux yet, but work is slowly progressing there.
>>
>> Signed-off-by: Nicholas Piggin <address@hidden>
>> ---
>> Changes since v4:
>> - Style
>>
>> hw/ppc/spapr.c | 1 +
>> hw/ppc/spapr_hcall.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 46 insertions(+)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 13c423347e..59cd24f9c3 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1066,6 +1066,7 @@ static void spapr_dt_rtas(SpaprMachineState *spapr,
>> void *fdt)
>> add_str(hypertas, "hcall-tce");
>> add_str(hypertas, "hcall-vio");
>> add_str(hypertas, "hcall-splpar");
>> + add_str(hypertas, "hcall-join");
>> add_str(hypertas, "hcall-bulk");
>> add_str(hypertas, "hcall-set-mode");
>> add_str(hypertas, "hcall-sprg0");
>> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
>> index 5e655172b2..57c1ee0fe1 100644
>> --- a/hw/ppc/spapr_hcall.c
>> +++ b/hw/ppc/spapr_hcall.c
>> @@ -1069,6 +1069,48 @@ static target_ulong h_cede(PowerPCCPU *cpu,
>> SpaprMachineState *spapr,
>> return H_SUCCESS;
>> }
>>
>> +static target_ulong h_join(PowerPCCPU *cpu, SpaprMachineState *spapr,
>> + target_ulong opcode, target_ulong *args)
>> +{
>> + CPUPPCState *env = &cpu->env;
>> + CPUState *cs;
>> + SpaprCpuState *spapr_cpu = spapr_cpu_state(cpu);
>> + bool last_unjoined = true;
>> +
>> + if (env->msr & (1ULL << MSR_EE)) {
>> + return H_BAD_MODE;
>> + }
>> +
>> + if (spapr_cpu->prod) {
>> + spapr_cpu->prod = false;
>> + return H_SUCCESS;
>> + }
>> +
>
> PAPR says that H_JOIN "performs the equivalent of a H_CONFER (proc=self)",
> unless called by the last unjoined thread, in which case H_CONTINUE
> should be returned. It thus seems that the spapr_cpu->prod check should
> be done after the loop below otherwise if the last active thread was
> just prodded (can happen?), it won't return the expected value, and...
Good lawyering, I would say you are right.
>> + CPU_FOREACH(cs) {
>> + PowerPCCPU *c = POWERPC_CPU(cs);
>> + CPUPPCState *e = &c->env;
>> + if (c == cpu) {
>> + continue;
>> + }
>> +
>> + /* Don't have a way to indicate joined, so use halted && MSR[EE]=0
>> */
>> + if (!cs->halted || (e->msr & (1ULL << MSR_EE))) {
>> + last_unjoined = false;
>> + break;
>> + }
>> + }
>> + if (last_unjoined) {
>> + return H_CONTINUE;
>> + }
>> +
>> + cs = CPU(cpu);
>> + cs->halted = 1;
>> + cs->exception_index = EXCP_HALTED;
>> + cs->exit_request = 1;
>> +
>> + return H_SUCCESS;
>
> ... then, you can maybe factor out this code to an h_confer_self()
> helper to be called by h_join() and h_confer() ?
I'll take a look.
Thanks,
Nick
- [Qemu-ppc] [PATCH v5 2/4] spapr: Implement H_PROD, (continued)