Re: [Qemu-devel] [PATCH 10/25] spapr: add MMIO handlers for the XIVE interrupt sources

[David Gibson]

On Tue, Nov 28, 2017 at 06:33:06PM +0000, Cédric Le Goater wrote:
> On 11/28/2017 06:38 AM, David Gibson wrote:
> > On Thu, Nov 23, 2017 at 02:29:40PM +0100, Cédric Le Goater wrote:
> >> Each interrupt source is associated with a two bit state machine
> >> called an Event State Buffer (ESB). The bits are named "P" (pending)
> >> and "Q" (queued) and can be controlled by MMIO. It is used to trigger
> >> events. See code for more details on the states and transitions.
> >>
> >> The MMIO space for the ESB translation is 512GB large on baremetal
> >> (powernv) systems and the BAR depends on the chip id. In our model for
> >> the sPAPR machine, we choose to only map a sub memory region for the
> >> provisionned IRQ numbers and to use the mapping address of chip 0 on a
> >> real system. The OS will get the address of the MMIO page of the ESB
> >> entry associated with an IRQ using the H_INT_GET_SOURCE_INFO hcall.
> >>
> >> Signed-off-by: Cédric Le Goater <address@hidden>
> >> ---
> >>  hw/intc/spapr_xive.c        | 268 
> >> +++++++++++++++++++++++++++++++++++++++++++-
> >>  include/hw/ppc/spapr_xive.h |   8 ++
> >>  2 files changed, 275 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
> >> index 66c533fb1d78..f45f50fd017e 100644
> >> --- a/hw/intc/spapr_xive.c
> >> +++ b/hw/intc/spapr_xive.c
> >> @@ -32,6 +32,216 @@ static void spapr_xive_irq(sPAPRXive *xive, int lisn)
> >>  }
> >>  
> >>  /*
> >> + * "magic" Event State Buffer (ESB) MMIO offsets.
> >> + *
> >> + * Each interrupt source has a 2-bit state machine called ESB
> >> + * which can be controlled by MMIO. It's made of 2 bits, P and
> >> + * Q. P indicates that an interrupt is pending (has been sent
> >> + * to a queue and is waiting for an EOI). Q indicates that the
> >> + * interrupt has been triggered while pending.
> >> + *
> >> + * This acts as a coalescing mechanism in order to guarantee
> >> + * that a given interrupt only occurs at most once in a queue.
> >> + *
> >> + * When doing an EOI, the Q bit will indicate if the interrupt
> >> + * needs to be re-triggered.
> >> + *
> >> + * The following offsets into the ESB MMIO allow to read or
> >> + * manipulate the PQ bits. They must be used with an 8-bytes
> >> + * load instruction. They all return the previous state of the
> >> + * interrupt (atomically).
> >> + *
> >> + * Additionally, some ESB pages support doing an EOI via a
> >> + * store at 0 and some ESBs support doing a trigger via a
> >> + * separate trigger page.
> >> + */
> >> +#define XIVE_ESB_GET            0x800
> >> +#define XIVE_ESB_SET_PQ_00      0xc00
> >> +#define XIVE_ESB_SET_PQ_01      0xd00
> >> +#define XIVE_ESB_SET_PQ_10      0xe00
> >> +#define XIVE_ESB_SET_PQ_11      0xf00
> >> +
> >> +#define XIVE_ESB_VAL_P          0x2
> >> +#define XIVE_ESB_VAL_Q          0x1
> >> +
> >> +#define XIVE_ESB_RESET          0x0
> >> +#define XIVE_ESB_PENDING        XIVE_ESB_VAL_P
> >> +#define XIVE_ESB_QUEUED         (XIVE_ESB_VAL_P | XIVE_ESB_VAL_Q)
> >> +#define XIVE_ESB_OFF            XIVE_ESB_VAL_Q
> >> +
> >> +static uint8_t spapr_xive_pq_get(sPAPRXive *xive, uint32_t lisn)
> >> +{
> >> +    uint32_t byte = lisn / 4;
> >> +    uint32_t bit  = (lisn % 4) * 2;
> >> +
> >> +    assert(byte < xive->sbe_size);
> >> +
> >> +    return (xive->sbe[byte] >> bit) & 0x3;
> >> +}
> >> +
> >> +static uint8_t spapr_xive_pq_set(sPAPRXive *xive, uint32_t lisn, uint8_t 
> >> pq)
> >> +{
> >> +    uint32_t byte = lisn / 4;
> >> +    uint32_t bit  = (lisn % 4) * 2;
> >> +    uint8_t old, new;
> >> +
> >> +    assert(byte < xive->sbe_size);
> >> +
> >> +    old = xive->sbe[byte];
> >> +
> >> +    new = xive->sbe[byte] & ~(0x3 << bit);
> >> +    new |= (pq & 0x3) << bit;
> >> +
> >> +    xive->sbe[byte] = new;
> >> +
> >> +    return (old >> bit) & 0x3;
> >> +}
> >> +
> >> +static bool spapr_xive_pq_eoi(sPAPRXive *xive, uint32_t lisn)
> >> +{
> >> +    uint8_t old_pq = spapr_xive_pq_get(xive, lisn);
> >> +
> >> +    switch (old_pq) {
> >> +    case XIVE_ESB_RESET:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_RESET);
> >> +        return false;
> >> +    case XIVE_ESB_PENDING:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_RESET);
> >> +        return false;
> >> +    case XIVE_ESB_QUEUED:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_PENDING);
> >> +        return true;
> >> +    case XIVE_ESB_OFF:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_OFF);
> >> +        return false;
> >> +    default:
> >> +         g_assert_not_reached();
> >> +    }
> >> +}
> >> +
> >> +static bool spapr_xive_pq_trigger(sPAPRXive *xive, uint32_t lisn)
> >> +{
> >> +    uint8_t old_pq = spapr_xive_pq_get(xive, lisn);
> >> +
> >> +    switch (old_pq) {
> >> +    case XIVE_ESB_RESET:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_PENDING);
> >> +        return true;
> >> +    case XIVE_ESB_PENDING:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_QUEUED);
> >> +        return true;
> >> +    case XIVE_ESB_QUEUED:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_QUEUED);
> >> +        return true;
> >> +    case XIVE_ESB_OFF:
> >> +        spapr_xive_pq_set(xive, lisn, XIVE_ESB_OFF);
> >> +        return false;
> >> +    default:
> >> +         g_assert_not_reached();
> >> +    }
> >> +}
> >> +
> >> +/*
> >> + * XIVE Interrupt Source MMIOs
> >> + */
> >> +static void spapr_xive_source_eoi(sPAPRXive *xive, uint32_t lisn)
> >> +{
> >> +    if (spapr_xive_irq_is_lsi(xive, lisn)) {
> >> +        xive->status[lisn] &= ~XIVE_STATUS_SENT;
> >> +    }
> >> +}
> >> +
> >> +/* TODO: handle second page
> >> + *
> >> + * Some HW use a separate page for trigger. We only support the case
> >> + * in which the trigger can be done in the same page as the EOI.
> >> + */
> >> +static uint64_t spapr_xive_esb_read(void *opaque, hwaddr addr, unsigned 
> >> size)
> >> +{
> >> +    sPAPRXive *xive = SPAPR_XIVE(opaque);
> >> +    uint32_t offset = addr & 0xF00;
> >> +    uint32_t lisn = addr >> xive->esb_shift;
> >> +    XiveIVE *ive;
> >> +    uint64_t ret = -1;
> >> +
> >> +    ive = spapr_xive_get_ive(xive, lisn);
> >> +    if (!ive || !(ive->w & IVE_VALID))  {
> >> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid LISN %d\n", lisn);
> >> +        goto out;
> >> +    }
> >> +
> >> +    switch (offset) {
> >> +    case 0:
> >> +        spapr_xive_source_eoi(xive, lisn);
> > 
> > Hrm.  I don't love that you're dealing with clearing that LSI bit
> > here, but setting it at a different level.
> > 
> > The state machines are doing my head in a bit, is there any way
> > you could derive the STATUS_SENT bit from the PQ bits?
> 
> Yes. I should. 
> 
> I am also lacking a guest driver to exercise these LSIs so I didn't
> pay a lot of attention to level interrupts. Any idea ?

How about an old-school emulated PCI device?  Maybe rtl8139?

> >> +        /* return TRUE or FALSE depending on PQ value */
> >> +        ret = spapr_xive_pq_eoi(xive, lisn);
> >> +        break;
> >> +
> >> +    case XIVE_ESB_GET:
> >> +        ret = spapr_xive_pq_get(xive, lisn);
> >> +        break;
> >> +
> >> +    case XIVE_ESB_SET_PQ_00:
> >> +    case XIVE_ESB_SET_PQ_01:
> >> +    case XIVE_ESB_SET_PQ_10:
> >> +    case XIVE_ESB_SET_PQ_11:
> >> +        ret = spapr_xive_pq_set(xive, lisn, (offset >> 8) & 0x3);
> >> +        break;
> >> +    default:
> >> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid ESB addr %d\n", 
> >> offset);
> >> +    }
> >> +
> >> +out:
> >> +    return ret;
> >> +}
> >> +
> >> +static void spapr_xive_esb_write(void *opaque, hwaddr addr,
> >> +                           uint64_t value, unsigned size)
> >> +{
> >> +    sPAPRXive *xive = SPAPR_XIVE(opaque);
> >> +    uint32_t offset = addr & 0xF00;
> >> +    uint32_t lisn = addr >> xive->esb_shift;
> >> +    XiveIVE *ive;
> >> +    bool notify = false;
> >> +
> >> +    ive = spapr_xive_get_ive(xive, lisn);
> >> +    if (!ive || !(ive->w & IVE_VALID))  {
> >> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid LISN %d\n", lisn);
> >> +        return;
> >> +    }
> >> +
> >> +    switch (offset) {
> >> +    case 0:
> >> +        /* TODO: should we trigger even if the IVE is masked ? */
> >> +        notify = spapr_xive_pq_trigger(xive, lisn);
> >> +        break;
> >> +    default:
> >> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid ESB write addr 
> >> %d\n",
> >> +                      offset);
> >> +        return;
> >> +    }
> >> +
> >> +    if (notify && !(ive->w & IVE_MASKED)) {
> >> +        qemu_irq_pulse(xive->qirqs[lisn]);
> >> +    }
> >> +}
> >> +
> >> +static const MemoryRegionOps spapr_xive_esb_ops = {
> >> +    .read = spapr_xive_esb_read,
> >> +    .write = spapr_xive_esb_write,
> >> +    .endianness = DEVICE_BIG_ENDIAN,
> >> +    .valid = {
> >> +        .min_access_size = 8,
> >> +        .max_access_size = 8,
> >> +    },
> >> +    .impl = {
> >> +        .min_access_size = 8,
> >> +        .max_access_size = 8,
> >> +    },
> >> +};
> >> +
> >> +/*
> >>   * XIVE Interrupt Source
> >>   */
> >>  static void spapr_xive_source_set_irq_msi(sPAPRXive *xive, int lisn, int 
> >> val)
> >> @@ -70,6 +280,33 @@ static void spapr_xive_source_set_irq(void *opaque, 
> >> int lisn, int val)
> >>  /*
> >>   * Main XIVE object
> >>   */
> >> +#define P9_MMIO_BASE     0x006000000000000ull
> >> +
> >> +/* VC BAR contains set translations for the ESBs and the EQs. */
> >> +#define VC_BAR_DEFAULT   0x10000000000ull
> >> +#define VC_BAR_SIZE      0x08000000000ull
> >> +#define ESB_SHIFT        16 /* One 64k page. OPAL has two */
> >> +
> >> +static uint64_t spapr_xive_esb_default_read(void *p, hwaddr offset,
> >> +                                            unsigned size)
> >> +{
> >> +    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u]\n",
> >> +                  __func__, offset, size);
> >> +    return 0;
> >> +}
> >> +
> >> +static void spapr_xive_esb_default_write(void *opaque, hwaddr offset,
> >> +                                         uint64_t value, unsigned size)
> >> +{
> >> +    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " 
> >> [%u]\n",
> >> +                  __func__, offset, value, size);
> >> +}
> >> +
> >> +static const MemoryRegionOps spapr_xive_esb_default_ops = {
> >> +    .read = spapr_xive_esb_default_read,
> >> +    .write = spapr_xive_esb_default_write,
> >> +    .endianness = DEVICE_BIG_ENDIAN,
> > 
> > I think you should at least have a valid access size field here.
> 
> yes. 
> 
> >> +};
> >>  
> >>  void spapr_xive_pic_print_info(sPAPRXive *xive, Monitor *mon)
> >>  {
> >> @@ -77,14 +314,19 @@ void spapr_xive_pic_print_info(sPAPRXive *xive, 
> >> Monitor *mon)
> >>  
> >>      for (i = 0; i < xive->nr_irqs; i++) {
> >>          XiveIVE *ive = &xive->ivt[i];
> >> +        uint8_t pq;
> >>  
> >>          if (!(ive->w & IVE_VALID)) {
> >>              continue;
> >>          }
> >>  
> >> -        monitor_printf(mon, "  %4x %s %s %08x %08x\n", i,
> >> +        pq = spapr_xive_pq_get(xive, i);
> >> +
> >> +        monitor_printf(mon, "  %4x %s %s %c%c %08x %08x\n", i,
> >>                         spapr_xive_irq_is_lsi(xive, i) ? "LSI" : "MSI",
> >>                         ive->w & IVE_MASKED ? "M" : " ",
> >> +                       pq & XIVE_ESB_VAL_P ? 'P' : '-',
> >> +                       pq & XIVE_ESB_VAL_Q ? 'Q' : '-',
> >>                         (int) GETFIELD(IVE_EQ_INDEX, ive->w),
> >>                         (int) GETFIELD(IVE_EQ_DATA, ive->w));
> >>      }
> >> @@ -104,6 +346,9 @@ void spapr_xive_reset(void *dev)
> >>              ive->w |= IVE_MASKED;
> >>          }
> >>      }
> >> +
> >> +    /* SBEs are initialized to 0b01 which corresponds to "ints off" */
> >> +    memset(xive->sbe, 0x55, xive->sbe_size);
> >>  }
> >>  
> >>  static void spapr_xive_realize(DeviceState *dev, Error **errp)
> >> @@ -123,6 +368,26 @@ static void spapr_xive_realize(DeviceState *dev, 
> >> Error **errp)
> >>      /* Allocate the IVT (Interrupt Virtualization Table) */
> >>      xive->ivt = g_malloc0(xive->nr_irqs * sizeof(XiveIVE));
> >>  
> >> +    /* Allocate SBEs (State Bit Entry). 2 bits, so 4 entries per byte */
> >> +    xive->sbe_size = DIV_ROUND_UP(xive->nr_irqs, 4);
> >> +    xive->sbe = g_malloc0(xive->sbe_size);
> >> +
> >> +    /* VC BAR. That's the full window but we will only map the
> >> +     * subregions in use. */
> >> +    xive->esb_base = (P9_MMIO_BASE | VC_BAR_DEFAULT);
> >> +    xive->esb_shift = ESB_SHIFT;
> > 
> > Any point to having this as a variable, if it's always the same size?
> 
> Well, it is related to the page size and we could have a HW configuration 
> with two pages, with one specific page for trigger. But we don't need to 
> model this, yet.  
> 
> The 'esb_shift' field is used in different places. I would rather
> keep it.

Hm, ok.

> >> +
> >> +    /* Install default memory region handlers to log bogus access */
> >> +    memory_region_init_io(&xive->esb_mr, NULL, 
> >> &spapr_xive_esb_default_ops,
> >> +                          NULL, "xive.esb.full", VC_BAR_SIZE);
> >> +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &xive->esb_mr);
> >> +
> >> +    /* Install the ESB memory region in the overall one */
> >> +    memory_region_init_io(&xive->esb_iomem, OBJECT(xive), 
> >> &spapr_xive_esb_ops,
> >> +                          xive, "xive.esb",
> >> +                          (1ull << xive->esb_shift) * xive->nr_irqs);
> >> +    memory_region_add_subregion(&xive->esb_mr, 0, &xive->esb_iomem);
> > 
> > Is there a benegit to to having these nested regions, rather than just
> > validating the lisn in the read/write functions?
> 
> No. this was to represent the full ESB space of the system but we can 
> reduce it to one region. This is not a problem I think.
> 
> >>      qemu_register_reset(spapr_xive_reset, dev);
> >>  }
> >>  
> >> @@ -152,6 +417,7 @@ static const VMStateDescription vmstate_spapr_xive = {
> >>          VMSTATE_STRUCT_VARRAY_UINT32_ALLOC(ivt, sPAPRXive, nr_irqs, 1,
> >>                                             vmstate_spapr_xive_ive, 
> >> XiveIVE),
> >>          VMSTATE_VBUFFER_UINT32(status, sPAPRXive, 1, NULL, nr_irqs),
> >> +        VMSTATE_VBUFFER_UINT32(sbe, sPAPRXive, 1, NULL, sbe_size),
> >>          VMSTATE_END_OF_LIST()
> >>      },
> >>  };
> >> diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
> >> index 6a799cdaba66..84c910e62e56 100644
> >> --- a/include/hw/ppc/spapr_xive.h
> >> +++ b/include/hw/ppc/spapr_xive.h
> >> @@ -42,6 +42,14 @@ struct sPAPRXive {
> >>  
> >>      /* XIVE internal tables */
> >>      XiveIVE      *ivt;
> >> +    uint8_t      *sbe;
> >> +    uint32_t     sbe_size;
> > 
> > sbe_size is derivable from nr_irqs, so I don't think there's a point
> > to storing it separately .
> 
> I needed the value for the vmstate macros.

Ah, right.


> 
> Thanks,
> 
> C. 
> 
>  
> >> +
> >> +    /* ESB memory region */
> >> +    uint32_t     esb_shift;
> >> +    hwaddr       esb_base;
> >> +    MemoryRegion esb_mr;
> >> +    MemoryRegion esb_iomem;
> >>  };
> >>  
> >>  static inline bool spapr_xive_irq_is_lsi(sPAPRXive *xive, int lisn)
> > 
> 

-- 
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

signature.asc
Description: PGP signature