Re: [Qemu-devel] [RFC PATCH 04/26] ppc/xive: introduce a skeleton for the XIVE interrupt controller model

[David Gibson]

On Wed, Jul 05, 2017 at 07:13:17PM +0200, Cédric Le Goater wrote:
> Let's provide an empty shell for the XIVE controller model with a
> couple of attributes for the IRQ number allocator. The latter is
> largely inspired by OPAL which allocates IPI IRQ numbers from the
> bottom of the IRQ number space and allocates the HW IRQ numbers from
> the top.
> 
> The number of IPIs is simply deduced from the max number of CPUs the
> guest supports and we provision a arbitrary number of HW irqs.
> 
> The XIVE object is kept private because it will hold internal tables
> which do not need to be exposed to sPAPR.
> 
> Signed-off-by: Cédric Le Goater <address@hidden>
> ---
>  default-configs/ppc64-softmmu.mak |  1 +
>  hw/intc/Makefile.objs             |  1 +
>  hw/intc/xive-internal.h           | 28 ++++++++++++
>  hw/intc/xive.c                    | 94 
> +++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/xive.h             | 27 +++++++++++
>  5 files changed, 151 insertions(+)
>  create mode 100644 hw/intc/xive-internal.h
>  create mode 100644 hw/intc/xive.c
>  create mode 100644 include/hw/ppc/xive.h
> 
> diff --git a/default-configs/ppc64-softmmu.mak 
> b/default-configs/ppc64-softmmu.mak
> index 46c95993217d..1179c07e6e9f 100644
> --- a/default-configs/ppc64-softmmu.mak
> +++ b/default-configs/ppc64-softmmu.mak
> @@ -56,6 +56,7 @@ CONFIG_SM501=y
>  CONFIG_XICS=$(CONFIG_PSERIES)
>  CONFIG_XICS_SPAPR=$(CONFIG_PSERIES)
>  CONFIG_XICS_KVM=$(and $(CONFIG_PSERIES),$(CONFIG_KVM))
> +CONFIG_XIVE=$(CONFIG_PSERIES)
>  # For PReP
>  CONFIG_SERIAL_ISA=y
>  CONFIG_MC146818RTC=y
> diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
> index 78426a7dafcd..28b83456bfcc 100644
> --- a/hw/intc/Makefile.objs
> +++ b/hw/intc/Makefile.objs
> @@ -35,6 +35,7 @@ obj-$(CONFIG_SH4) += sh_intc.o
>  obj-$(CONFIG_XICS) += xics.o
>  obj-$(CONFIG_XICS_SPAPR) += xics_spapr.o
>  obj-$(CONFIG_XICS_KVM) += xics_kvm.o
> +obj-$(CONFIG_XIVE) += xive.o
>  obj-$(CONFIG_POWERNV) += xics_pnv.o
>  obj-$(CONFIG_ALLWINNER_A10_PIC) += allwinner-a10-pic.o
>  obj-$(CONFIG_S390_FLIC) += s390_flic.o
> diff --git a/hw/intc/xive-internal.h b/hw/intc/xive-internal.h
> new file mode 100644
> index 000000000000..155c2dcd6066
> --- /dev/null
> +++ b/hw/intc/xive-internal.h
> @@ -0,0 +1,28 @@
> +/*
> + * Copyright 2016,2017 IBM Corporation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +#ifndef _INTC_XIVE_INTERNAL_H
> +#define _INTC_XIVE_INTERNAL_H
> +
> +#include <hw/sysbus.h>
> +
> +struct XIVE {
> +    SysBusDevice parent;

XIVE probably shouldn't be a SysBusDevice.  According to agraf, that
should only be used for things which have an MMIO presence on a bus
structure that's not worth the bother of more specifically modelling.

I don't think that's the case for XIVE, so it should just have
TYPE_DEVICE as its parent.  There are several pseries things which
already get this wrong (mostly because I made them before fully
understanding the role of the SysBus), but we should avoid adding
others.

> +    /* Properties */
> +    uint32_t     nr_targets;
> +
> +    /* IRQ number allocator */
> +    uint32_t     int_count;     /* Number of interrupts: nr_targets + HW 
> IRQs */
> +    uint32_t     int_base;      /* Min index */
> +    uint32_t     int_max;       /* Max index */
> +    uint32_t     int_hw_bot;    /* Bottom index of HW IRQ allocator */
> +    uint32_t     int_ipi_top;   /* Highest IPI index handed out so far + 1 */
> +};
> +
> +#endif /* _INTC_XIVE_INTERNAL_H */
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> new file mode 100644
> index 000000000000..5b4ea915d87c
> --- /dev/null
> +++ b/hw/intc/xive.c
> @@ -0,0 +1,94 @@
> +/*
> + * QEMU PowerPC XIVE model
> + *
> + * Copyright (c) 2017, IBM Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +#include "qemu/osdep.h"
> +#include "qemu/log.h"
> +#include "qapi/error.h"
> +#include "target/ppc/cpu.h"
> +#include "sysemu/cpus.h"
> +#include "sysemu/dma.h"
> +#include "monitor/monitor.h"
> +#include "hw/ppc/xive.h"
> +
> +#include "xive-internal.h"
> +
> +/*
> + * Main XIVE object

As with XICs, does it really make sense for there to be a "main" XIVE
object, or should be an interface attached to the machine?

> + */
> +
> +/* Let's provision some HW IRQ numbers. We could use a XIVE property
> + * also but it does not seem necessary for the moment.
> + */
> +#define MAX_HW_IRQS_ENTRIES (8 * 1024)
> +
> +static void xive_init(Object *obj)
> +{
> +    ;
> +}
> +
> +static void xive_realize(DeviceState *dev, Error **errp)
> +{
> +    XIVE *x = XIVE(dev);
> +
> +    if (!x->nr_targets) {
> +        error_setg(errp, "Number of interrupt targets needs to be greater 
> 0");
> +        return;
> +    }
> +
> +    /* Initialize IRQ number allocator. Let's use a base number if we
> +     * need to introduce a notion of blocks one day.
> +     */
> +    x->int_base = 0;
> +    x->int_count = x->nr_targets + MAX_HW_IRQS_ENTRIES;
> +    x->int_max = x->int_base + x->int_count;
> +    x->int_hw_bot = x->int_max;
> +    x->int_ipi_top = x->int_base;
> +
> +    /* Reserve some numbers as OPAL does ? */
> +    if (x->int_ipi_top < 0x10) {
> +        x->int_ipi_top = 0x10;
> +    }

I'm somewhat uncomfortable with an irq allocater here in the intc
code.  As a rule, irq allocation is the responsibility of the machine,
not any sub-component.  Furthermore, it should allocate in a way which
is repeatable, since they need to stay stable across reboots and
migrations.

And, yes, we have an allocator of sorts in XICS - it has caused a
number of problems in the past.

> +}
> +
> +static Property xive_properties[] = {
> +    DEFINE_PROP_UINT32("nr-targets", XIVE, nr_targets, 0),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void xive_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->realize = xive_realize;
> +    dc->props = xive_properties;
> +    dc->desc = "XIVE";
> +}
> +
> +static const TypeInfo xive_info = {
> +    .name = TYPE_XIVE,
> +    .parent = TYPE_SYS_BUS_DEVICE,
> +    .instance_init = xive_init,
> +    .instance_size = sizeof(XIVE),
> +    .class_init = xive_class_init,
> +};
> +
> +static void xive_register_types(void)
> +{
> +    type_register_static(&xive_info);
> +}
> +
> +type_init(xive_register_types)
> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> new file mode 100644
> index 000000000000..863f5a9c6b5f
> --- /dev/null
> +++ b/include/hw/ppc/xive.h
> @@ -0,0 +1,27 @@
> +/*
> + * QEMU PowerPC XIVE model
> + *
> + * Copyright (c) 2017, IBM Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef PPC_XIVE_H
> +#define PPC_XIVE_H
> +
> +typedef struct XIVE XIVE;
> +
> +#define TYPE_XIVE "xive"
> +#define XIVE(obj) OBJECT_CHECK(XIVE, (obj), TYPE_XIVE)
> +
> +#endif /* PPC_XIVE_H */

-- 
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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