Re: [Qemu-ppc] [PATCH v6 2/4] spapr: introduce a fixed IRQ number space

[David Gibson]

On Tue, Jul 31, 2018 at 07:39:45PM +0200, Greg Kurz wrote:
> On Mon, 30 Jul 2018 16:11:32 +0200
> Cédric Le Goater <address@hidden> wrote:
> 
> > This proposal introduces a new IRQ number space layout using static
> > numbers for all devices, depending on a device index, and a bitmap
> > allocator for the MSI IRQ numbers which are negotiated by the guest at
> > runtime.
> > 
> > As the VIO device model does not have a device index but a "reg"
> > property, we introduce a formula to compute an IRQ number from a "reg"
> > value. It should minimize most of the collisions.
> > 
> > The previous layout is kept in pre-3.1 machines raising the
> > 'legacy_irq_allocation' machine class flag.
> > 
> > Signed-off-by: Cédric Le Goater <address@hidden>
> > ---
> >  include/hw/ppc/spapr.h     |  5 +++
> >  include/hw/ppc/spapr_irq.h | 32 ++++++++++++++++++
> >  hw/ppc/spapr.c             | 32 ++++++++++++++++++
> >  hw/ppc/spapr_events.c      | 12 ++++---
> >  hw/ppc/spapr_irq.c         | 56 ++++++++++++++++++++++++++++++++
> >  hw/ppc/spapr_pci.c         | 29 +++++++++++++----
> >  hw/ppc/spapr_vio.c         | 66 ++++++++++++++++++++++++++++++++++----
> >  hw/ppc/Makefile.objs       |  2 +-
> >  8 files changed, 216 insertions(+), 18 deletions(-)
> >  create mode 100644 include/hw/ppc/spapr_irq.h
> >  create mode 100644 hw/ppc/spapr_irq.c
> > 
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 7e5de1a6fd42..73067f5ee8aa 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -8,6 +8,7 @@
> >  #include "hw/ppc/spapr_drc.h"
> >  #include "hw/mem/pc-dimm.h"
> >  #include "hw/ppc/spapr_ovec.h"
> > +#include "hw/ppc/spapr_irq.h"
> >  
> >  struct VIOsPAPRBus;
> >  struct sPAPRPHBState;
> > @@ -101,6 +102,8 @@ struct sPAPRMachineClass {
> >      bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs 
> > */
> >      bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
> >      bool pre_2_10_has_unused_icps;
> > +    bool legacy_irq_allocation;
> > +
> >      void (*phb_placement)(sPAPRMachineState *spapr, uint32_t index,
> >                            uint64_t *buid, hwaddr *pio, 
> >                            hwaddr *mmio32, hwaddr *mmio64,
> > @@ -167,6 +170,8 @@ struct sPAPRMachineState {
> >      char *kvm_type;
> >  
> >      const char *icp_type;
> > +    int32_t irq_map_nr;
> > +    unsigned long *irq_map;
> >  
> >      bool cmd_line_caps[SPAPR_CAP_NUM];
> >      sPAPRCapabilities def, eff, mig;
> > diff --git a/include/hw/ppc/spapr_irq.h b/include/hw/ppc/spapr_irq.h
> > new file mode 100644
> > index 000000000000..6f7f50548809
> > --- /dev/null
> > +++ b/include/hw/ppc/spapr_irq.h
> > @@ -0,0 +1,32 @@
> > +/*
> > + * QEMU PowerPC sPAPR IRQ backend definitions
> > + *
> > + * Copyright (c) 2018, IBM Corporation.
> > + *
> > + * This code is licensed under the GPL version 2 or later. See the
> > + * COPYING file in the top-level directory.
> > + */
> > +
> > +#ifndef HW_SPAPR_IRQ_H
> > +#define HW_SPAPR_IRQ_H
> > +
> > +/*
> > + * IRQ range offsets per device type
> > + */
> > +#define SPAPR_IRQ_EPOW       0x1000  /* XICS_IRQ_BASE offset */
> > +#define SPAPR_IRQ_HOTPLUG    0x1001
> > +#define SPAPR_IRQ_VIO        0x1100  /* 256 VIO devices */
> > +#define SPAPR_IRQ_PCI_LSI    0x1200  /* 32+ PHBs devices */
> > +
> > +#define SPAPR_IRQ_MSI        0x1300  /* Offset of the dynamic range covered
> > +                                      * by the bitmap allocator */
> > +
> > +typedef struct sPAPRMachineState sPAPRMachineState;
> > +
> 
> Old compilers (GCC < 4.6) might complain about 'redefinition of typedef' if
> some file, say hw/ppc/spapr.c, includes both this header and "hw/ppc/xics.h".
> We had several build breaks detected by 'make address@hidden'...
> The correct way to address this would be to move the typedef to the
> "qemu/typedefs.h" header.
> 
> This being said, address@hidden vanished with commit e7b3af81597,
> so I guess we don't support such old distros anymore, and we can live with
> duplicate typedefs.
> 
> > +void spapr_irq_msi_init(sPAPRMachineState *spapr, uint32_t nr_msis);
> > +int spapr_irq_msi_alloc(sPAPRMachineState *spapr, uint32_t num, bool align,
> > +                        Error **errp);
> > +void spapr_irq_msi_free(sPAPRMachineState *spapr, int irq, uint32_t num);
> > +void spapr_irq_msi_reset(sPAPRMachineState *spapr);
> > +
> > +#endif
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 3c72173c7e0f..792e24453d8b 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -189,6 +189,11 @@ static void xics_system_init(MachineState *machine, 
> > int nr_irqs, Error **errp)
> >      sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
> >      Error *local_err = NULL;
> >  
> > +    /* 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);
> > +    }
> > +
> >      if (kvm_enabled()) {
> >          if (machine_kernel_irqchip_allowed(machine) &&
> >              !xics_kvm_init(spapr, &local_err)) {
> > @@ -1636,6 +1641,10 @@ static void spapr_machine_reset(void)
> >          ppc_set_compat(first_ppc_cpu, spapr->max_compat_pvr, &error_fatal);
> >      }
> >  
> > +    if (!SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +        spapr_irq_msi_reset(spapr);
> > +    }
> > +
> >      qemu_devices_reset();
> >  
> >      /* DRC reset may cause a device to be unplugged. This will cause 
> > troubles
> > @@ -1910,6 +1919,24 @@ static const VMStateDescription 
> > vmstate_spapr_patb_entry = {
> >      },
> >  };
> >  
> > +static bool spapr_irq_map_needed(void *opaque)
> > +{
> > +    sPAPRMachineState *spapr = opaque;
> > +
> > +    return spapr->irq_map && !bitmap_empty(spapr->irq_map, 
> > spapr->irq_map_nr);
> > +}
> > +
> > +static const VMStateDescription vmstate_spapr_irq_map = {
> > +    .name = "spapr_irq_map",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .needed = spapr_irq_map_needed,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_BITMAP(irq_map, sPAPRMachineState, 0, irq_map_nr),
> > +        VMSTATE_END_OF_LIST()
> > +    },
> > +};
> > +
> >  static const VMStateDescription vmstate_spapr = {
> >      .name = "spapr",
> >      .version_id = 3,
> > @@ -1937,6 +1964,7 @@ static const VMStateDescription vmstate_spapr = {
> >          &vmstate_spapr_cap_cfpc,
> >          &vmstate_spapr_cap_sbbc,
> >          &vmstate_spapr_cap_ibs,
> > +        &vmstate_spapr_irq_map,
> >          NULL
> >      }
> >  };
> > @@ -4085,8 +4113,12 @@ static void 
> > spapr_machine_3_0_instance_options(MachineState *machine)
> >  
> >  static void spapr_machine_3_0_class_options(MachineClass *mc)
> >  {
> > +    sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> > +
> >      spapr_machine_3_1_class_options(mc);
> >      SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_3_0);
> > +
> > +    smc->legacy_irq_allocation = true;
> >  }
> >  
> >  DEFINE_SPAPR_MACHINE(3_0, "3.0", false);
> > diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> > index e4f5946a2188..32719a1b72d0 100644
> > --- a/hw/ppc/spapr_events.c
> > +++ b/hw/ppc/spapr_events.c
> > @@ -707,9 +707,11 @@ void spapr_clear_pending_events(sPAPRMachineState 
> > *spapr)
> >  
> >  void spapr_events_init(sPAPRMachineState *spapr)
> >  {
> > -    int epow_irq;
> > +    int epow_irq = SPAPR_IRQ_EPOW;
> >  
> > -    epow_irq = spapr_irq_findone(spapr, &error_fatal);
> > +    if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +        epow_irq = spapr_irq_findone(spapr, &error_fatal);
> > +    }
> >  
> >      spapr_irq_claim(spapr, epow_irq, false, &error_fatal);
> >  
> > @@ -729,9 +731,11 @@ void spapr_events_init(sPAPRMachineState *spapr)
> >       * checking that it's enabled.
> >       */
> >      if (spapr->use_hotplug_event_source) {
> > -        int hp_irq;
> > +        int hp_irq = SPAPR_IRQ_HOTPLUG;
> >  
> > -        hp_irq = spapr_irq_findone(spapr, &error_fatal);
> > +        if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +            hp_irq = spapr_irq_findone(spapr, &error_fatal);
> > +        }
> >  
> >          spapr_irq_claim(spapr, hp_irq, false, &error_fatal);
> >  
> > diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> > new file mode 100644
> > index 000000000000..24e9c1d4433c
> > --- /dev/null
> > +++ b/hw/ppc/spapr_irq.c
> > @@ -0,0 +1,56 @@
> > +/*
> > + * QEMU PowerPC sPAPR IRQ interface
> > + *
> > + * Copyright (c) 2018, IBM Corporation.
> > + *
> > + * This code is licensed under the GPL version 2 or later. See the
> > + * COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu/log.h"
> > +#include "qemu/error-report.h"
> > +#include "qapi/error.h"
> > +#include "hw/ppc/spapr.h"
> > +#include "hw/ppc/xics.h"
> > +
> > +void spapr_irq_msi_init(sPAPRMachineState *spapr, uint32_t nr_msis)
> > +{
> > +    spapr->irq_map_nr = nr_msis;
> > +    spapr->irq_map = bitmap_new(spapr->irq_map_nr);
> > +}
> > +
> > +int spapr_irq_msi_alloc(sPAPRMachineState *spapr, uint32_t num, bool align,
> > +                        Error **errp)
> > +{
> > +    int irq;
> > +
> > +    /*
> > +     * 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;
> > +
> > +    irq = bitmap_find_next_zero_area(spapr->irq_map, spapr->irq_map_nr, 0, 
> > num,
> > +                                     align);
> > +    if (irq == spapr->irq_map_nr) {
> > +        error_setg(errp, "can't find a free %d-IRQ block", num);
> > +        return -1;
> > +    }
> > +
> > +    bitmap_set(spapr->irq_map, irq, num);
> > +
> > +    return irq + SPAPR_IRQ_MSI;
> > +}
> > +
> > +void spapr_irq_msi_free(sPAPRMachineState *spapr, int irq, uint32_t num)
> > +{
> > +    bitmap_clear(spapr->irq_map, irq - SPAPR_IRQ_MSI, num);
> > +}
> > +
> > +void spapr_irq_msi_reset(sPAPRMachineState *spapr)
> > +{
> > +    bitmap_clear(spapr->irq_map, 0, spapr->irq_map_nr);
> > +}
> > diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> > index 497b896c7d24..3791ced6c536 100644
> > --- a/hw/ppc/spapr_pci.c
> > +++ b/hw/ppc/spapr_pci.c
> > @@ -334,6 +334,9 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, 
> > sPAPRMachineState *spapr,
> >              return;
> >          }
> >  
> > +        if (!SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +            spapr_irq_msi_free(spapr, msi->first_irq, msi->num);
> > +        }
> >          spapr_irq_free(spapr, msi->first_irq, msi->num);
> >          if (msi_present(pdev)) {
> >              spapr_msi_setmsg(pdev, 0, false, 0, 0);
> > @@ -372,7 +375,13 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, 
> > sPAPRMachineState *spapr,
> >      }
> >  
> >      /* Allocate MSIs */
> > -    irq = spapr_irq_find(spapr, req_num, ret_intr_type == RTAS_TYPE_MSI, 
> > &err);
> > +    if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +        irq = spapr_irq_find(spapr, req_num, ret_intr_type == 
> > RTAS_TYPE_MSI,
> > +                             &err);
> > +    } else {
> > +        irq = spapr_irq_msi_alloc(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);
> > @@ -392,6 +401,9 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, 
> > sPAPRMachineState *spapr,
> >  
> >      /* Release previous MSIs */
> >      if (msi) {
> > +        if (!SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +            spapr_irq_msi_free(spapr, msi->first_irq, msi->num);
> > +        }
> 
> SPAPR_MACHINE_GET_CLASS() does all the recursive type checking, and you
> call it three times. Even if this isn't a hot path, maybe cache this in
> an smc variable at the beginning of the function as we do pretty much
> everywhere else. Also this would give prettier code IMHO.

I agree with Greg that this would be a nice improvement, but it can
wait until a followup.

> >          spapr_irq_free(spapr, msi->first_irq, msi->num);
> >          g_hash_table_remove(phb->msi, &config_addr);
> >      }
> > @@ -1705,14 +1717,16 @@ static void spapr_phb_realize(DeviceState *dev, 
> > Error **errp)
> >  
> >      /* Initialize the LSI table */
> >      for (i = 0; i < PCI_NUM_PINS; i++) {
> > -        uint32_t irq;
> > +        uint32_t irq = SPAPR_IRQ_PCI_LSI + sphb->index * PCI_NUM_PINS + i;
> >          Error *local_err = NULL;
> >  
> > -        irq = spapr_irq_findone(spapr, &local_err);
> > -        if (local_err) {
> > -            error_propagate(errp, local_err);
> > -            error_prepend(errp, "can't allocate LSIs: ");
> > -            return;
> > +        if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> 
> Same remark. There's another SPAPR_MACHINE_GET_CLASS() user in this
> function.
> 
> > +            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, true, &local_err);
> > @@ -2123,6 +2137,7 @@ 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));
> >  
> >      /* Dynamic DMA window */
> > diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
> > index be9af71437cc..840d4a3c451c 100644
> > --- a/hw/ppc/spapr_vio.c
> > +++ b/hw/ppc/spapr_vio.c
> > @@ -37,12 +37,13 @@
> >  
> >  #include "hw/ppc/spapr.h"
> >  #include "hw/ppc/spapr_vio.h"
> > -#include "hw/ppc/xics.h"
> >  #include "hw/ppc/fdt.h"
> >  #include "trace.h"
> >  
> >  #include <libfdt.h>
> >  
> > +#define SPAPR_VIO_REG_BASE 0x71000000
> > +
> >  static void spapr_vio_get_irq(Object *obj, Visitor *v, const char *name,
> >                                void *opaque, Error **errp)
> >  {
> > @@ -445,6 +446,55 @@ static void spapr_vio_busdev_reset(DeviceState *qdev)
> >      }
> >  }
> >  
> > +/*
> > + * The register property of a VIO device is defined in livirt using
> > + * 0x1000 as a base register number plus a 0x1000 increment. For the
> > + * VIO tty device, the base number is changed to 0x30000000. QEMU uses
> > + * a base register number of 0x71000000 and then a simple increment.
> > + *
> > + * The formula below tries to compute a unique index number from the
> > + * register value that will be used to define the IRQ number of the
> > + * VIO device.
> > + *
> > + * A maximum of 256 VIO devices is covered. Collisions are possible
> > + * but they will be detected when the IRQ is claimed.
> > + */
> > +static inline uint32_t spapr_vio_reg_to_irq(uint32_t reg)
> > +{
> > +    uint32_t irq;
> > +
> > +    if (reg >= SPAPR_VIO_REG_BASE) {
> > +        /*
> > +         * VIO device register values when allocated by QEMU. For
> > +         * these, we simply mask the high bits to fit the overall
> > +         * range: [0x00 - 0xff].
> > +         *
> > +         * The nvram VIO device (reg=0x71000000) is a static device of
> > +         * the pseries machine and so is always allocated by QEMU. Its
> > +         * IRQ number is 0x0.
> > +         */
> > +        irq = reg & 0xff;
> > +
> > +    } else if (reg >= 0x30000000) {
> > +        /*
> > +         * VIO tty devices register values, when allocated by livirt,
> > +         * are mapped in range [0xf0 - 0xff], gives us a maximum of 16
> > +         * vtys.
> > +         */
> > +        irq = 0xf0 | ((reg >> 12) & 0xf);
> > +
> > +    } else {
> > +        /*
> > +         * Other VIO devices register values, when allocated by
> > +         * livirt, should be mapped in range [0x00 - 0xef]. Conflicts
> > +         * will be detected when IRQ is claimed.
> > +         */
> > +        irq = (reg >> 12) & 0xff;
> > +    }
> > +
> 
> Nice formula :)
> 
> The patch looks quite good to me, and my remarks about 
> SPAPR_MACHINE_GET_CLASS()
> can be addressed in a followup, so:
> 
> Reviewed-by: Greg Kurz <address@hidden>
> 
> > +    return SPAPR_IRQ_VIO | irq;
> > +}
> > +
> >  static void spapr_vio_busdev_realize(DeviceState *qdev, Error **errp)
> >  {
> >      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> > @@ -485,10 +535,14 @@ static void spapr_vio_busdev_realize(DeviceState 
> > *qdev, Error **errp)
> >      }
> >  
> >      if (!dev->irq) {
> > -        dev->irq = spapr_irq_findone(spapr, &local_err);
> > -        if (local_err) {
> > -            error_propagate(errp, local_err);
> > -            return;
> > +        dev->irq = spapr_vio_reg_to_irq(dev->reg);
> > +
> > +        if (SPAPR_MACHINE_GET_CLASS(spapr)->legacy_irq_allocation) {
> > +            dev->irq = spapr_irq_findone(spapr, &local_err);
> > +            if (local_err) {
> > +                error_propagate(errp, local_err);
> > +                return;
> > +            }
> >          }
> >      }
> >  
> > @@ -557,7 +611,7 @@ VIOsPAPRBus *spapr_vio_bus_init(void)
> >      /* Create bus on bridge device */
> >      qbus = qbus_create(TYPE_SPAPR_VIO_BUS, dev, "spapr-vio");
> >      bus = SPAPR_VIO_BUS(qbus);
> > -    bus->next_reg = 0x71000000;
> > +    bus->next_reg = SPAPR_VIO_REG_BASE;
> >  
> >      /* hcall-vio */
> >      spapr_register_hypercall(H_VIO_SIGNAL, h_vio_signal);
> > diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
> > index bcab6323b7ed..4ab556467289 100644
> > --- a/hw/ppc/Makefile.objs
> > +++ b/hw/ppc/Makefile.objs
> > @@ -4,7 +4,7 @@ obj-y += ppc.o ppc_booke.o fdt.o
> >  obj-$(CONFIG_PSERIES) += spapr.o spapr_caps.o spapr_vio.o spapr_events.o
> >  obj-$(CONFIG_PSERIES) += spapr_hcall.o spapr_iommu.o spapr_rtas.o
> >  obj-$(CONFIG_PSERIES) += spapr_pci.o spapr_rtc.o spapr_drc.o spapr_rng.o
> > -obj-$(CONFIG_PSERIES) += spapr_cpu_core.o spapr_ovec.o
> > +obj-$(CONFIG_PSERIES) += spapr_cpu_core.o spapr_ovec.o spapr_irq.o
> >  # IBM PowerNV
> >  obj-$(CONFIG_POWERNV) += pnv.o pnv_xscom.o pnv_core.o pnv_lpc.o pnv_psi.o 
> > pnv_occ.o pnv_bmc.o
> >  ifeq ($(CONFIG_PCI)$(CONFIG_PSERIES)$(CONFIG_LINUX), yyy)
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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