Re: [Qemu-ppc] [RFC PATCH 3/3] spapr: generate a CAS reset for the XIVE exploitation mode

[Cédric Le Goater]

On 09/10/2017 05:19 AM, David Gibson wrote:
> On Fri, Sep 08, 2017 at 04:33:44PM +0200, Cédric Le Goater wrote:
>> When the platform and the guest agree on using the XIVE exploitation
>> mode for interrupts, the "interrupt-controller" node needs to reflect
>> the change and the device tree needs an update.
>>
>> Reseting the guest after the CAS negotiation makes this change
>> possible, as the device tree is built at reset time. We use the
>> 'ov5_cas' field to check which interrupt model was negotiated before
>> reset and populate the tree accordingly.
>>
>> Signed-off-by: Cédric Le Goater <address@hidden>
> 
> Looks reasonable, though I'm not going to apply it until we actually
> have something to go..

Yes. I agree. A simplified XIVE patchset for sPAPR should be ready 
soon for comments. Please see below for one question.

>> ---
>>  hw/ppc/spapr.c       | 6 +++++-
>>  hw/ppc/spapr_hcall.c | 6 ++++++
>>  2 files changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 3e3ff1fbc988..be467ab61ad0 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1073,7 +1073,11 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr,
>>      _FDT(fdt_setprop_cell(fdt, 0, "#size-cells", 2));
>>  
>>      /* /interrupt controller */
>> -    spapr_dt_xics(xics_max_server_number(), fdt, PHANDLE_XICP);
>> +    if (!spapr_ovec_test(spapr->ov5_cas, OV5_XIVE_EXPLOIT)) {
>> +        spapr_dt_xics(xics_max_server_number(), fdt, PHANDLE_XICP);
>> +    } else {
>> +        /* populate device tree for XIVE */ ;
> 
> .. here.

How should we handle the PHANDLE_XICP for xive ? as it is done
for xics ? 

The DT node is now :    "address@hidden"

>> +    }
>>  
>>      ret = spapr_populate_memory(spapr, fdt);
>>      if (ret < 0) {
>> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
>> index 92f1e21358b8..ba00b8d3fdd6 100644
>> --- a/hw/ppc/spapr_hcall.c
>> +++ b/hw/ppc/spapr_hcall.c
>> @@ -1613,6 +1613,12 @@ static target_ulong 
>> h_client_architecture_support(PowerPCCPU *cpu,
>>              (spapr_h_cas_compose_response(spapr, args[1], args[2],
>>                                            ov5_updates) != 0);
>>      }
>> +
>> +    /* We need to rebuild the device tree for XIVE, generate a reset */
>> +    if (!spapr->cas_reboot) {
>> +        spapr->cas_reboot = spapr_ovec_test(ov5_updates, OV5_XIVE_EXPLOIT);
>> +    }
> 
> At some point we may well want to make XIVE exploitation the default
> for POWER9 guests, but that's a detail easily adjusted later.

ah yes. we can do that.

Thanks,

C. 
 
>>      spapr_ovec_cleanup(ov5_updates);
>>  
>>      if (spapr->cas_reboot) {
>