Re: [Qemu-devel] [PATCH 1/3] spapr: split the IRQ allocation sequence

[Cédric Le Goater]

On 06/18/2018 02:16 PM, David Gibson wrote:
> On Mon, Jun 18, 2018 at 02:00:06PM +1000, David Gibson wrote:
>> On Fri, Jun 15, 2018 at 01:53:01PM +0200, Cédric Le Goater wrote:
>>> Today, when a device requests for IRQ number in a sPAPR machine, the
>>> spapr_irq_alloc() routine first scans the ICSState status array to
>>> find an empty slot and then performs the assignement of the selected
>>> numbers. Split this sequence in two distinct routines : spapr_irq_find()
>>> for lookups and spapr_irq_claim() for claiming the IRQ numbers.
>>>
>>> This will ease the introduction of a static layout of IRQ numbers.
>>>
>>> Signed-off-by: Cédric Le Goater <address@hidden>
>>> ---
>>>  include/hw/ppc/spapr.h |  5 ++++
>>>  hw/ppc/spapr.c         | 64 
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  hw/ppc/spapr_events.c  | 18 ++++++++++----
>>>  hw/ppc/spapr_pci.c     | 19 ++++++++++++---
>>>  hw/ppc/spapr_vio.c     | 10 +++++++-
>>>  5 files changed, 108 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>>> index 3388750fc795..6088f44c1b2a 100644
>>> --- a/include/hw/ppc/spapr.h
>>> +++ b/include/hw/ppc/spapr.h
>>> @@ -776,6 +776,11 @@ int spapr_irq_alloc(sPAPRMachineState *spapr, int 
>>> irq_hint, bool lsi,
>>>                      Error **errp);
>>>  int spapr_irq_alloc_block(sPAPRMachineState *spapr, int num, bool lsi,
>>>                            bool align, Error **errp);
>>> +int spapr_irq_find(sPAPRMachineState *spapr, int num, bool align,
>>> +                   Error **errp);
>>> +#define spapr_irq_findone(spapr, errp) spapr_irq_find(spapr, 1, false, 
>>> errp)
>>> +int spapr_irq_claim(sPAPRMachineState *spapr, int irq, int num, bool lsi,
>>> +                    Error **errp);
>>
>> Unlike find, there's no reason we need to atomically claim a block of
>> irqs.  So I think claim should just grab a single irq.  Callers can
>> loop if they need multiple irqs.
> 
> Actually.. I take that back.  We don't *need* a block-claim interface,
> but if it's convenient there's no strong reason not to (as long as
> therer aren't *both* single and block interfaces, which there aren't).

Ah ! I usually code important matters in the morning and so I have 
removed it already. It was only used under spapr_pci for the msi.  

> So feel free to run with that, once the rollback bugs Greg pointed out
> are fixed.

The code was ok I think. But anyway, it's dead now. We can always 
add it back.

Thanks,

C. 
 
>> Other than that and the minor points Greg noted, this looks good.
>>
>>>  void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num);
>>>  qemu_irq spapr_qirq(sPAPRMachineState *spapr, int irq);
>>>  
>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>>> index f59999daacfc..b1d19b328166 100644
>>> --- a/hw/ppc/spapr.c
>>> +++ b/hw/ppc/spapr.c
>>> @@ -3810,6 +3810,36 @@ static int ics_find_free_block(ICSState *ics, int 
>>> num, int alignnum)
>>>      return -1;
>>>  }
>>>  
>>> +int spapr_irq_find(sPAPRMachineState *spapr, int num, bool align, Error 
>>> **errp)
>>> +{
>>> +    ICSState *ics = spapr->ics;
>>> +    int first = -1;
>>> +
>>> +    assert(ics);
>>> +
>>> +    /*
>>> +     * MSIMesage::data is used for storing VIRQ so
>>> +     * it has to be aligned to num to support multiple
>>> +     * MSI vectors. MSI-X is not affected by this.
>>> +     * The hint is used for the first IRQ, the rest should
>>> +     * be allocated continuously.
>>> +     */
>>> +    if (align) {
>>> +        assert((num == 1) || (num == 2) || (num == 4) ||
>>> +               (num == 8) || (num == 16) || (num == 32));
>>> +        first = ics_find_free_block(ics, num, num);
>>> +    } else {
>>> +        first = ics_find_free_block(ics, num, 1);
>>> +    }
>>> +
>>> +    if (first < 0) {
>>> +        error_setg(errp, "can't find a free %d-IRQ block", num);
>>> +        return -1;
>>> +    }
>>> +
>>> +    return first + ics->offset;
>>> +}
>>> +
>>>  /*
>>>   * Allocate the IRQ number and set the IRQ type, LSI or MSI
>>>   */
>>> @@ -3888,6 +3918,40 @@ int spapr_irq_alloc_block(sPAPRMachineState *spapr, 
>>> int num, bool lsi,
>>>      return first;
>>>  }
>>>  
>>> +int spapr_irq_claim(sPAPRMachineState *spapr, int irq, int num, bool lsi,
>>> +                    Error **errp)
>>> +{
>>> +    ICSState *ics = spapr->ics;
>>> +    int i;
>>> +    int srcno = irq - ics->offset;
>>> +    int ret = 0;
>>> +
>>> +    assert(ics);
>>> +
>>> +    if (!ics_valid_irq(ics, irq) || !ics_valid_irq(ics, irq + num)) {
>>> +        return -1;
>>> +    }
>>> +
>>> +    for (i = srcno; i < srcno + num; ++i) {
>>> +        if (ICS_IRQ_FREE(ics, i)) {
>>> +            spapr_irq_set_lsi(spapr, i + ics->offset, lsi);
>>> +        } else {
>>> +            error_setg(errp, "IRQ %d is not free", i + ics->offset);
>>> +            ret = -1;
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    /* we could call spapr_irq_free() when rolling back */
>>> +    if (ret) {
>>> +        while (--i >= srcno) {
>>> +            memset(&ics->irqs[i], 0, sizeof(ICSIRQState));
>>> +        }
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>  void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num)
>>>  {
>>>      ICSState *ics = spapr->ics;
>>> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
>>> index 86836f0626dc..3b6ae7272092 100644
>>> --- a/hw/ppc/spapr_events.c
>>> +++ b/hw/ppc/spapr_events.c
>>> @@ -707,13 +707,18 @@ void spapr_clear_pending_events(sPAPRMachineState 
>>> *spapr)
>>>  
>>>  void spapr_events_init(sPAPRMachineState *spapr)
>>>  {
>>> +    int epow_irq;
>>> +
>>> +    epow_irq = spapr_irq_findone(spapr, &error_fatal);
>>> +
>>> +    spapr_irq_claim(spapr, epow_irq, 1, false, &error_fatal);
>>> +
>>>      QTAILQ_INIT(&spapr->pending_events);
>>>  
>>>      spapr->event_sources = spapr_event_sources_new();
>>>  
>>>      spapr_event_sources_register(spapr->event_sources, EVENT_CLASS_EPOW,
>>> -                                 spapr_irq_alloc(spapr, 0, false,
>>> -                                                  &error_fatal));
>>> +                                 epow_irq);
>>>  
>>>      /* NOTE: if machine supports modern/dedicated hotplug event source,
>>>       * we add it to the device-tree unconditionally. This means we may
>>> @@ -724,9 +729,14 @@ void spapr_events_init(sPAPRMachineState *spapr)
>>>       * checking that it's enabled.
>>>       */
>>>      if (spapr->use_hotplug_event_source) {
>>> +        int hp_irq;
>>> +
>>> +        hp_irq = spapr_irq_findone(spapr, &error_fatal);
>>> +
>>> +        spapr_irq_claim(spapr, hp_irq, 1, false, &error_fatal);
>>> +
>>>          spapr_event_sources_register(spapr->event_sources, 
>>> EVENT_CLASS_HOT_PLUG,
>>> -                                     spapr_irq_alloc(spapr, 0, false,
>>> -                                                      &error_fatal));
>>> +                                     hp_irq);
>>>      }
>>>  
>>>      spapr->epow_notifier.notify = spapr_powerdown_req;
>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>>> index f936ce63effa..7394c62b4a8b 100644
>>> --- a/hw/ppc/spapr_pci.c
>>> +++ b/hw/ppc/spapr_pci.c
>>> @@ -371,8 +371,14 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, 
>>> sPAPRMachineState *spapr,
>>>      }
>>>  
>>>      /* Allocate MSIs */
>>> -    irq = spapr_irq_alloc_block(spapr, req_num, false,
>>> -                           ret_intr_type == RTAS_TYPE_MSI, &err);
>>> +    irq = spapr_irq_find(spapr, req_num, ret_intr_type == RTAS_TYPE_MSI, 
>>> &err);
>>> +    if (err) {
>>> +        error_reportf_err(err, "Can't allocate MSIs for device %x: ",
>>> +                          config_addr);
>>> +        rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
>>> +        return;
>>> +    }
>>> +    spapr_irq_claim(spapr, irq, req_num, false, &err);
>>>      if (err) {
>>>          error_reportf_err(err, "Can't allocate MSIs for device %x: ",
>>>                            config_addr);
>>> @@ -1698,7 +1704,14 @@ static void spapr_phb_realize(DeviceState *dev, 
>>> Error **errp)
>>>          uint32_t irq;
>>>          Error *local_err = NULL;
>>>  
>>> -        irq = spapr_irq_alloc_block(spapr, 1, true, false, &local_err);
>>> +        irq = spapr_irq_findone(spapr, &local_err);
>>> +        if (local_err) {
>>> +            error_propagate(errp, local_err);
>>> +            error_prepend(errp, "can't allocate LSIs: ");
>>> +            return;
>>> +        }
>>> +
>>> +        spapr_irq_claim(spapr, irq, 1, true, &local_err);
>>>          if (local_err) {
>>>              error_propagate(errp, local_err);
>>>              error_prepend(errp, "can't allocate LSIs: ");
>>> diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
>>> index 4555c648a8e2..ad9b56e28447 100644
>>> --- a/hw/ppc/spapr_vio.c
>>> +++ b/hw/ppc/spapr_vio.c
>>> @@ -475,7 +475,15 @@ static void spapr_vio_busdev_realize(DeviceState 
>>> *qdev, Error **errp)
>>>          dev->qdev.id = id;
>>>      }
>>>  
>>> -    dev->irq = spapr_irq_alloc(spapr, dev->irq, false, &local_err);
>>> +    if (!dev->irq) {
>>> +        dev->irq = spapr_irq_findone(spapr, &local_err);
>>> +        if (local_err) {
>>> +            error_propagate(errp, local_err);
>>> +            return;
>>> +        }
>>> +    }
>>> +
>>> +    spapr_irq_claim(spapr, dev->irq, 1, false, &local_err);
>>>      if (local_err) {
>>>          error_propagate(errp, local_err);
>>>          return;
>>
> 
> 
>