Re: [Qemu-devel] [PATCH v5 06/36] ppc/xive: add support for the END Event State buffers

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Nov 16, 2018 at 11:56:59AM +0100, Cédric Le Goater wrote:
> The Event Notification Descriptor also contains two Event State
> Buffers providing further coalescing of interrupts, one for the
> notification event (ESn) and one for the escalation events (ESe). A
> MMIO page is assigned for each to control the EOI through loads
> only. Stores are not allowed.
> 
> The END ESBs are modeled through an object resembling the 'XiveSource'
> It is stateless as the END state bits are backed into the XiveEND
> structure under the XiveRouter and the MMIO accesses follow the same
> rules as for the standard source ESBs.
> 
> END ESBs are not supported by the Linux drivers neither on OPAL nor on
> sPAPR. Nevetherless, it provides a mean to study the question in the
> future and validates a bit more the XIVE model.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/xive.h |  20 ++++++
>  hw/intc/xive.c        | 160 +++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 178 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> index ce62aaf28343..24301bf2076d 100644
> --- a/include/hw/ppc/xive.h
> +++ b/include/hw/ppc/xive.h
> @@ -208,6 +208,26 @@ int xive_router_get_end(XiveRouter *xrtr, uint8_t end_blk, uint32_t end_idx,
>  int xive_router_set_end(XiveRouter *xrtr, uint8_t end_blk, uint32_t end_idx,
>                          XiveEND *end);
>  
> +/*
> + * XIVE END ESBs
> + */
> +
> +#define TYPE_XIVE_END_SOURCE "xive-end-source"
> +#define XIVE_END_SOURCE(obj) \
> +    OBJECT_CHECK(XiveENDSource, (obj), TYPE_XIVE_END_SOURCE)

Is there a particular reason to make this a full QOM object, rather
than just embedding it in the XiveRouter?

> +typedef struct XiveENDSource {
> +    SysBusDevice parent;
> +
> +    uint32_t        nr_ends;
> +
> +    /* ESB memory region */
> +    uint32_t        esb_shift;
> +    MemoryRegion    esb_mmio;
> +
> +    XiveRouter      *xrtr;
> +} XiveENDSource;
> +
>  /*
>   * For legacy compatibility, the exceptions define up to 256 different
>   * priorities. P9 implements only 9 levels : 8 active levels [0 - 7]
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index 9cb001e7b540..5a8882d47a98 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -622,8 +622,18 @@ static void xive_router_end_notify(XiveRouter *xrtr, uint8_t end_blk,
>       * even futher coalescing in the Router
>       */
>      if (!(end.w0 & END_W0_UCOND_NOTIFY)) {
> -        qemu_log_mask(LOG_UNIMP, "XIVE: !UCOND_NOTIFY not implemented\n");
> -        return;
> +        uint8_t pq = GETFIELD(END_W1_ESn, end.w1);
> +        bool notify = xive_esb_trigger(&pq);
> +
> +        if (pq != GETFIELD(END_W1_ESn, end.w1)) {
> +            end.w1 = SETFIELD(END_W1_ESn, end.w1, pq);
> +            xive_router_set_end(xrtr, end_blk, end_idx, &end);
> +        }
> +
> +        /* ESn[Q]=1 : end of notification */
> +        if (!notify) {
> +            return;
> +        }
>      }
>  
>      /*
> @@ -706,6 +716,151 @@ void xive_eas_pic_print_info(XiveEAS *eas, uint32_t lisn, Monitor *mon)
>                     (uint32_t) GETFIELD(EAS_END_DATA, eas->w));
>  }
>  
> +/*
> + * END ESB MMIO loads
> + */
> +static uint64_t xive_end_source_read(void *opaque, hwaddr addr, unsigned size)
> +{
> +    XiveENDSource *xsrc = XIVE_END_SOURCE(opaque);
> +    XiveRouter *xrtr = xsrc->xrtr;
> +    uint32_t offset = addr & 0xFFF;
> +    uint8_t end_blk;
> +    uint32_t end_idx;
> +    XiveEND end;
> +    uint32_t end_esmask;
> +    uint8_t pq;
> +    uint64_t ret = -1;
> +
> +    end_blk = xrtr->chip_id;
> +    end_idx = addr >> (xsrc->esb_shift + 1);
> +    if (xive_router_get_end(xrtr, end_blk, end_idx, &end)) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: No END %x/%x\n", end_blk,
> +                      end_idx);
> +        return -1;
> +    }
> +
> +    if (!(end.w0 & END_W0_VALID)) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: END %x/%x is invalid\n",
> +                      end_blk, end_idx);
> +        return -1;
> +    }
> +
> +    end_esmask = addr_is_even(addr, xsrc->esb_shift) ? END_W1_ESn : END_W1_ESe;
> +    pq = GETFIELD(end_esmask, end.w1);
> +
> +    switch (offset) {
> +    case XIVE_ESB_LOAD_EOI ... XIVE_ESB_LOAD_EOI + 0x7FF:
> +        ret = xive_esb_eoi(&pq);
> +
> +        /* Forward the source event notification for routing ?? */
> +        break;
> +
> +    case XIVE_ESB_GET ... XIVE_ESB_GET + 0x3FF:
> +        ret = pq;
> +        break;
> +
> +    case XIVE_ESB_SET_PQ_00 ... XIVE_ESB_SET_PQ_00 + 0x0FF:
> +    case XIVE_ESB_SET_PQ_01 ... XIVE_ESB_SET_PQ_01 + 0x0FF:
> +    case XIVE_ESB_SET_PQ_10 ... XIVE_ESB_SET_PQ_10 + 0x0FF:
> +    case XIVE_ESB_SET_PQ_11 ... XIVE_ESB_SET_PQ_11 + 0x0FF:
> +        ret = xive_esb_set(&pq, (offset >> 8) & 0x3);
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid END ESB load addr %d\n",
> +                      offset);
> +        return -1;
> +    }
> +
> +    if (pq != GETFIELD(end_esmask, end.w1)) {
> +        end.w1 = SETFIELD(end_esmask, end.w1, pq);
> +        xive_router_set_end(xrtr, end_blk, end_idx, &end);
> +    }

We can probably share some more code with XiveSource here, but that's
something that can be refined later.

> +
> +    return ret;
> +}
> +
> +/*
> + * END ESB MMIO stores are invalid
> + */
> +static void xive_end_source_write(void *opaque, hwaddr addr,
> +                                  uint64_t value, unsigned size)
> +{
> +    qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid ESB write addr 0x%"
> +                  HWADDR_PRIx"\n", addr);
> +}
> +
> +static const MemoryRegionOps xive_end_source_ops = {
> +    .read = xive_end_source_read,
> +    .write = xive_end_source_write,
> +    .endianness = DEVICE_BIG_ENDIAN,
> +    .valid = {
> +        .min_access_size = 8,
> +        .max_access_size = 8,
> +    },
> +    .impl = {
> +        .min_access_size = 8,
> +        .max_access_size = 8,
> +    },
> +};
> +
> +static void xive_end_source_realize(DeviceState *dev, Error **errp)
> +{
> +    XiveENDSource *xsrc = XIVE_END_SOURCE(dev);
> +    Object *obj;
> +    Error *local_err = NULL;
> +
> +    obj = object_property_get_link(OBJECT(dev), "xive", &local_err);
> +    if (!obj) {
> +        error_propagate(errp, local_err);
> +        error_prepend(errp, "required link 'xive' not found: ");
> +        return;
> +    }
> +
> +    xsrc->xrtr = XIVE_ROUTER(obj);
> +
> +    if (!xsrc->nr_ends) {
> +        error_setg(errp, "Number of interrupt needs to be greater than 0");
> +        return;
> +    }
> +
> +    if (xsrc->esb_shift != XIVE_ESB_4K &&
> +        xsrc->esb_shift != XIVE_ESB_64K) {
> +        error_setg(errp, "Invalid ESB shift setting");
> +        return;
> +    }
> +
> +    /*
> +     * Each END is assigned an even/odd pair of MMIO pages, the even page
> +     * manages the ESn field while the odd page manages the ESe field.
> +     */
> +    memory_region_init_io(&xsrc->esb_mmio, OBJECT(xsrc),
> +                          &xive_end_source_ops, xsrc, "xive.end",
> +                          (1ull << (xsrc->esb_shift + 1)) * xsrc->nr_ends);
> +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &xsrc->esb_mmio);
> +}
> +
> +static Property xive_end_source_properties[] = {
> +    DEFINE_PROP_UINT32("nr-ends", XiveENDSource, nr_ends, 0),
> +    DEFINE_PROP_UINT32("shift", XiveENDSource, esb_shift, XIVE_ESB_64K),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void xive_end_source_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->desc    = "XIVE END Source";
> +    dc->props   = xive_end_source_properties;
> +    dc->realize = xive_end_source_realize;
> +}
> +
> +static const TypeInfo xive_end_source_info = {
> +    .name          = TYPE_XIVE_END_SOURCE,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(XiveENDSource),
> +    .class_init    = xive_end_source_class_init,
> +};
> +
>  /*
>   * XIVE Fabric
>   */
> @@ -720,6 +875,7 @@ static void xive_register_types(void)
>      type_register_static(&xive_source_info);
>      type_register_static(&xive_fabric_info);
>      type_register_static(&xive_router_info);
> +    type_register_static(&xive_end_source_info);
>  }
>  
>  type_init(xive_register_types)

-- 
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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