Re: [Qemu-ppc] [PATCH for-2.12 v3 05/11] spapr: introduce an IRQ allocator using a bitmap

[Cédric Le Goater]

On 11/14/2017 09:42 AM, Greg Kurz wrote:
> On Fri, 10 Nov 2017 15:20:11 +0000
> Cédric Le Goater <address@hidden> wrote:
> 
>> Let's define a new set of XICSFabric IRQ operations for the latest
>> pseries machine. These simply use a a bitmap 'irq_map' as a IRQ number
>> allocator.
>>
>> The previous pseries machines keep the old set of IRQ operations using
>> the ICSIRQState array.
>>
>> Signed-off-by: Cédric Le Goater <address@hidden>
>> ---
>>
>>  Changes since v2 :
>>
>>  - introduced a second set of XICSFabric IRQ operations for older
>>    pseries machines
>>
>>  hw/ppc/spapr.c         | 76 
>> ++++++++++++++++++++++++++++++++++++++++++++++----
>>  include/hw/ppc/spapr.h |  3 ++
>>  2 files changed, 74 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 4bdceb45a14f..4ef0b73559ca 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1681,6 +1681,22 @@ static const VMStateDescription 
>> vmstate_spapr_patb_entry = {
>>      },
>>  };
>>  
>> +static bool spapr_irq_map_needed(void *opaque)
>> +{
>> +    return true;
> 
> I see that the next patch adds some code to avoid sending the
> bitmap if it doesn't contain state, but I guess you should also
> explicitly have this function to return false for older machine
> types (see remark below).
> 
>> +}
>> +
>> +static const VMStateDescription vmstate_spapr_irq_map = {
>> +    .name = "spapr_irq_map",
>> +    .version_id = 0,
>> +    .minimum_version_id = 0,
>> +    .needed = spapr_irq_map_needed,
>> +    .fields = (VMStateField[]) {
>> +        VMSTATE_BITMAP(irq_map, sPAPRMachineState, 0, nr_irqs),
>> +        VMSTATE_END_OF_LIST()
>> +    },
>> +};
>> +
>>  static const VMStateDescription vmstate_spapr = {
>>      .name = "spapr",
>>      .version_id = 3,
>> @@ -1700,6 +1716,7 @@ static const VMStateDescription vmstate_spapr = {
>>          &vmstate_spapr_ov5_cas,
>>          &vmstate_spapr_patb_entry,
>>          &vmstate_spapr_pending_events,
>> +        &vmstate_spapr_irq_map,
>>          NULL
>>      }
>>  };
>> @@ -2337,8 +2354,12 @@ static void ppc_spapr_init(MachineState *machine)
>>      /* Setup a load limit for the ramdisk leaving room for SLOF and FDT */
>>      load_limit = MIN(spapr->rma_size, RTAS_MAX_ADDR) - FW_OVERHEAD;
>>  
>> +    /* Initialize the IRQ allocator */
>> +    spapr->nr_irqs  = XICS_IRQS_SPAPR;
>> +    spapr->irq_map  = bitmap_new(spapr->nr_irqs);
>> +
> 
> I think you should introduce a sPAPRMachineClass::has_irq_bitmap boolean
> so that the bitmap is only allocated for newer machine types. And you should
> then use this flag in spapr_irq_map_needed() above.

yes. I can add a boot to be more explicit on the use of the bitmap.

Thanks,

C. 


> 
> Apart from that, the rest of the patch looks good.
> 
>>      /* Set up Interrupt Controller before we create the VCPUs */
>> -    xics_system_init(machine, XICS_IRQS_SPAPR, &error_fatal);
>> +    xics_system_init(machine, spapr->nr_irqs, &error_fatal);
>>  
>>      /* Set up containers for ibm,client-architecture-support negotiated 
>> options
>>       */
>> @@ -3560,7 +3581,7 @@ static int ics_find_free_block(ICSState *ics, int num, 
>> int alignnum)
>>      return -1;
>>  }
>>  
>> -static bool spapr_irq_test(XICSFabric *xi, int irq)
>> +static bool spapr_irq_test_2_11(XICSFabric *xi, int irq)
>>  {
>>      sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>>      ICSState *ics = spapr->ics;
>> @@ -3569,7 +3590,7 @@ static bool spapr_irq_test(XICSFabric *xi, int irq)
>>      return !ICS_IRQ_FREE(ics, srcno);
>>  }
>>  
>> -static int spapr_irq_alloc_block(XICSFabric *xi, int count, int align)
>> +static int spapr_irq_alloc_block_2_11(XICSFabric *xi, int count, int align)
>>  {
>>      sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>>      ICSState *ics = spapr->ics;
>> @@ -3583,7 +3604,7 @@ static int spapr_irq_alloc_block(XICSFabric *xi, int 
>> count, int align)
>>      return srcno + ics->offset;
>>  }
>>  
>> -static void spapr_irq_free_block(XICSFabric *xi, int irq, int num)
>> +static void spapr_irq_free_block_2_11(XICSFabric *xi, int irq, int num)
>>  {
>>      sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>>      ICSState *ics = spapr->ics;
>> @@ -3601,6 +3622,46 @@ static void spapr_irq_free_block(XICSFabric *xi, int 
>> irq, int num)
>>      }
>>  }
>>  
>> +static bool spapr_irq_test(XICSFabric *xi, int irq)
>> +{
>> +    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>> +    int srcno = irq - spapr->ics->offset;
>> +
>> +    return test_bit(srcno, spapr->irq_map);
>> +}
>> +
>> +static int spapr_irq_alloc_block(XICSFabric *xi, int count, int align)
>> +{
>> +    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>> +    int start = 0;
>> +    int srcno;
>> +
>> +    /*
>> +     * The 'align_mask' parameter of bitmap_find_next_zero_area()
>> +     * should be one less than a power of 2; 0 means no
>> +     * alignment. Adapt the 'align' value of the former allocator to
>> +     * fit the requirements of bitmap_find_next_zero_area()
>> +     */
>> +    align -= 1;
>> +
>> +    srcno = bitmap_find_next_zero_area(spapr->irq_map, spapr->nr_irqs, 
>> start,
>> +                                       count, align);
>> +    if (srcno == spapr->nr_irqs) {
>> +        return -1;
>> +    }
>> +
>> +    bitmap_set(spapr->irq_map, srcno, count);
>> +    return srcno + spapr->ics->offset;
>> +}
>> +
>> +static void spapr_irq_free_block(XICSFabric *xi, int irq, int num)
>> +{
>> +    sPAPRMachineState *spapr = SPAPR_MACHINE(xi);
>> +    int srcno = irq - spapr->ics->offset;
>> +
>> +    bitmap_clear(spapr->irq_map, srcno, num);
>> +}
>> +
>>  static void spapr_pic_print_info(InterruptStatsProvider *obj,
>>                                   Monitor *mon)
>>  {
>> @@ -3778,7 +3839,12 @@ static void 
>> spapr_machine_2_11_instance_options(MachineState *machine)
>>  
>>  static void spapr_machine_2_11_class_options(MachineClass *mc)
>>  {
>> -    /* Defaults for the latest behaviour inherited from the base class */
>> +    XICSFabricClass *xic = XICS_FABRIC_CLASS(mc);
>> +
>> +    spapr_machine_2_12_class_options(mc);
>> +    xic->irq_test = spapr_irq_test_2_11;
>> +    xic->irq_alloc_block = spapr_irq_alloc_block_2_11;
>> +    xic->irq_free_block = spapr_irq_free_block_2_11;
>>  }
>>  
>>  DEFINE_SPAPR_MACHINE(2_11, "2.11", false);
>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
>> index 9d21ca9bde3a..5835c694caff 100644
>> --- a/include/hw/ppc/spapr.h
>> +++ b/include/hw/ppc/spapr.h
>> @@ -7,6 +7,7 @@
>>  #include "hw/ppc/spapr_drc.h"
>>  #include "hw/mem/pc-dimm.h"
>>  #include "hw/ppc/spapr_ovec.h"
>> +#include "qemu/bitmap.h"
>>  
>>  struct VIOsPAPRBus;
>>  struct sPAPRPHBState;
>> @@ -78,6 +79,8 @@ struct sPAPRMachineState {
>>      struct VIOsPAPRBus *vio_bus;
>>      QLIST_HEAD(, sPAPRPHBState) phbs;
>>      struct sPAPRNVRAM *nvram;
>> +    int32_t nr_irqs;
>> +    unsigned long *irq_map;
>>      ICSState *ics;
>>      sPAPRRTCState rtc;
>>  
>