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

[Greg Kurz]

On Fri, 15 Jun 2018 13:53:01 +0200
Cédric Le Goater <address@hidden> 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);
>  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)) {

I guess it is okay to assume that if the first and last irqs are valid,
so are all numbers in between. Shouldn't the second check be against
irq + num - 1 though ?

This lacks an error_setg() BTW.

> +        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));
> +        }
> +    }

Hmm... I guess we should free the whole range otherwise we leak
srcno + num - i irqs, preferably using spapr_irq_free() to match
the traces from spapr_irq_alloc().

Alternatively, the rollback could be pushed to the callers.

Rest looks good.

> +
> +    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;