Re: [Qemu-devel] [PATCH v2 1/2] spapr: introduce a spapr_irq class 'nr_msis' attribute

["Cédric Le Goater" <clg@kaod.org>]

On 09/11/2018 09:34 AM, Greg Kurz wrote:
> On Tue, 11 Sep 2018 07:55:02 +0200
> Cédric Le Goater <clg@kaod.org> wrote:
> 
>> The number of MSI interrupts a sPAPR machine can allocate is in direct
>> relation with the number of interrupts of the sPAPRIrq backend. Define
>> statically this value at the sPAPRIrq class level and use it for the
>> "ibm,pe-total-#msi" property of the sPAPR PHB.
>>
>> According to the PAPR specs, "ibm,pe-total-#msi" defines the maximum
>> number of MSIs that are available to the PE. We choose to advertise
>> the maximum number of MSIs that are available to the machine for
>> simplicity of the model and to avoid segmenting the MSI interrupt pool
>> which can be easily shared. If the pool limit is reached, it can be
>> extended dynamically.
>>
>> Finally, remove XICS_IRQS_SPAPR which is now unused.
>>
>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>> ---
> 
> Looks good to me. Just one comment below.
> 
>>  include/hw/ppc/spapr_irq.h | 1 +
>>  include/hw/ppc/xics.h      | 2 --
>>  hw/ppc/spapr_irq.c         | 9 +++++++--
>>  hw/ppc/spapr_pci.c         | 5 +++--
>>  4 files changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/hw/ppc/spapr_irq.h b/include/hw/ppc/spapr_irq.h
>> index 0e98c4474bb2..650f810ad2aa 100644
>> --- a/include/hw/ppc/spapr_irq.h
>> +++ b/include/hw/ppc/spapr_irq.h
>> @@ -31,6 +31,7 @@ void spapr_irq_msi_reset(sPAPRMachineState *spapr);
>>  
>>  typedef struct sPAPRIrq {
>>      uint32_t    nr_irqs;
>> +    uint32_t    nr_msis;
>>  
>>      void (*init)(sPAPRMachineState *spapr, Error **errp);
>>      int (*claim)(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp);
>> diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
>> index 9c2916c9b23a..9958443d1984 100644
>> --- a/include/hw/ppc/xics.h
>> +++ b/include/hw/ppc/xics.h
>> @@ -181,8 +181,6 @@ typedef struct XICSFabricClass {
>>      ICPState *(*icp_get)(XICSFabric *xi, int server);
>>  } XICSFabricClass;
>>  
>> -#define XICS_IRQS_SPAPR               1024
>> -
>>  void spapr_dt_xics(int nr_servers, void *fdt, uint32_t phandle);
>>  
>>  ICPState *xics_icp_get(XICSFabric *xi, int server);
>> diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
>> index 0cbb5dd39368..fe8be5f5217a 100644
>> --- a/hw/ppc/spapr_irq.c
>> +++ b/hw/ppc/spapr_irq.c
>> @@ -99,7 +99,7 @@ static void spapr_irq_init_xics(sPAPRMachineState *spapr, Error **errp)
>>  
>>      /* Initialize the MSI IRQ allocator. */
>>      if (!SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
>> -        spapr_irq_msi_init(spapr, XICS_IRQ_BASE + nr_irqs - SPAPR_IRQ_MSI);
>> +        spapr_irq_msi_init(spapr, smc->irq->nr_msis);
>>      }
>>  
>>      if (kvm_enabled()) {
>> @@ -195,8 +195,13 @@ static void spapr_irq_print_info_xics(sPAPRMachineState *spapr, Monitor *mon)
>>      ics_pic_print_info(spapr->ics, mon);
>>  }
>>  
>> +#define SPAPR_IRQ_XICS_NR_IRQS     0x400
>> +#define SPAPR_IRQ_XICS_NR_MSIS     \
>> +    (XICS_IRQ_BASE + SPAPR_IRQ_XICS_NR_IRQS - SPAPR_IRQ_MSI)
>> +
>>  sPAPRIrq spapr_irq_xics = {
>> -    .nr_irqs     = XICS_IRQS_SPAPR,
>> +    .nr_irqs     = SPAPR_IRQ_XICS_NR_IRQS,
>> +    .nr_msis     = SPAPR_IRQ_XICS_NR_MSIS,
>>  
>>      .init        = spapr_irq_init_xics,
>>      .claim       = spapr_irq_claim_xics,
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index 6bcb4f419b6b..bb736177e76c 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -2121,6 +2121,7 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>>      sPAPRTCETable *tcet;
>>      PCIBus *bus = PCI_HOST_BRIDGE(phb)->bus;
>>      sPAPRFDT s_fdt;
>> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
>>  
> 
> It is a bit unfortunate to add another user of qdev_get_machine()...
> 
>>      /* Start populating the FDT */
>>      nodename = g_strdup_printf("pci@%" PRIx64, phb->buid);
>> @@ -2138,8 +2139,8 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>>      _FDT(fdt_setprop(fdt, bus_off, "ranges", &ranges, sizeof_ranges));
>>      _FDT(fdt_setprop(fdt, bus_off, "reg", &bus_reg, sizeof(bus_reg)));
>>      _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pci-config-space-type", 0x1));
>> -    /* TODO: fine tune the total count of allocatable MSIs per PHB */
>> -    _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pe-total-#msi", XICS_IRQS_SPAPR));
>> +    _FDT(fdt_setprop_cell(fdt, bus_off, "ibm,pe-total-#msi",
>> +                          smc->irq->nr_msis));
>>  
> 
> ... and to expose machine class internals. Since spapr_populate_pci_dt() is only
> called from the core machine code, maybe have the caller to pass the number of
> MSIs ?

yes we could add an extra parameter to spapr_populate_pci_dt()

> Anyway, this can be done in a followup patch so:
> 
> Reviewed-by: Greg Kurz <groug@kaod.org>

Thanks,

C.
> 
>>      /* Dynamic DMA window */
>>      if (phb->ddw_enabled) {
>