Re: [Qemu-devel] [PATCH v5 15/36] spapr: introdude a new machine IRQ backend for XIVE

From: David Gibson <david@gibson.dropbear.id.au>
To: "Cédric Le Goater" <clg@kaod.org>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [Qemu-devel] [PATCH v5 15/36] spapr: introdude a new machine IRQ backend for XIVE
Date: Wed, 28 Nov 2018 14:28:19 +1100	[thread overview]
Message-ID: <20181128032819.GY2251@umbus.fritz.box> (raw)
In-Reply-To: <20181116105729.23240-16-clg@kaod.org>

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On Fri, Nov 16, 2018 at 11:57:08AM +0100, Cédric Le Goater wrote:
> The XIVE IRQ backend uses the same layout as the new XICS backend but
> covers the full range of the IRQ number space. The IRQ numbers for the
> CPU IPIs are allocated at the bottom of this space, below 4K, to
> preserve compatibility with XICS which does not use that range.
> 
> This should be enough given that the maximum number of CPUs is 1024
> for the sPAPR machine under QEMU. For the record, the biggest POWER8
> or POWER9 system has a maximum of 1536 HW threads (16 sockets, 192
> cores, SMT8).
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/spapr.h     |   2 +
>  include/hw/ppc/spapr_irq.h |   7 ++-
>  hw/ppc/spapr.c             |   2 +-
>  hw/ppc/spapr_irq.c         | 119 ++++++++++++++++++++++++++++++++++++-
>  4 files changed, 124 insertions(+), 6 deletions(-)
> 
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 6279711fe8f7..1fbc2663e06c 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -16,6 +16,7 @@ typedef struct sPAPREventLogEntry sPAPREventLogEntry;
>  typedef struct sPAPREventSource sPAPREventSource;
>  typedef struct sPAPRPendingHPT sPAPRPendingHPT;
>  typedef struct ICSState ICSState;
> +typedef struct sPAPRXive sPAPRXive;
>  
>  #define HPTE64_V_HPTE_DIRTY     0x0000000000000040ULL
>  #define SPAPR_ENTRY_POINT       0x100
> @@ -175,6 +176,7 @@ struct sPAPRMachineState {
>      const char *icp_type;
>      int32_t irq_map_nr;
>      unsigned long *irq_map;
> +    sPAPRXive  *xive;
>  
>      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
> index 0e9229bf219e..c854ae527808 100644
> --- a/include/hw/ppc/spapr_irq.h
> +++ b/include/hw/ppc/spapr_irq.h
> @@ -13,6 +13,7 @@
>  /*
>   * IRQ range offsets per device type
>   */
> +#define SPAPR_IRQ_IPI        0x0
>  #define SPAPR_IRQ_EPOW       0x1000  /* XICS_IRQ_BASE offset */
>  #define SPAPR_IRQ_HOTPLUG    0x1001
>  #define SPAPR_IRQ_VIO        0x1100  /* 256 VIO devices */
> @@ -33,7 +34,8 @@ typedef struct sPAPRIrq {
>      uint32_t    nr_irqs;
>      uint32_t    nr_msis;
>  
> -    void (*init)(sPAPRMachineState *spapr, int nr_irqs, Error **errp);
> +    void (*init)(sPAPRMachineState *spapr, int nr_irqs, int nr_servers,
> +                 Error **errp);
>      int (*claim)(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp);
>      void (*free)(sPAPRMachineState *spapr, int irq, int num);
>      qemu_irq (*qirq)(sPAPRMachineState *spapr, int irq);
> @@ -42,8 +44,9 @@ typedef struct sPAPRIrq {
>  
>  extern sPAPRIrq spapr_irq_xics;
>  extern sPAPRIrq spapr_irq_xics_legacy;
> +extern sPAPRIrq spapr_irq_xive;
>  
> -void spapr_irq_init(sPAPRMachineState *spapr, Error **errp);
> +void spapr_irq_init(sPAPRMachineState *spapr, int nr_servers, Error **errp);

I don't see why nr_servers needs to become a parameter, since it can
be derived from spapr within this routine.

>  int spapr_irq_claim(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp);
>  void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num);
>  qemu_irq spapr_qirq(sPAPRMachineState *spapr, int irq);
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index e470efe7993c..9f8c19e56e7a 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2594,7 +2594,7 @@ static void spapr_machine_init(MachineState *machine)
>      spapr_set_vsmt_mode(spapr, &error_fatal);
>  
>      /* Set up Interrupt Controller before we create the VCPUs */
> -    spapr_irq_init(spapr, &error_fatal);
> +    spapr_irq_init(spapr, xics_max_server_number(spapr), &error_fatal);

We should rename xics_max_server_number() since it's no longer xics
specific.

>      /* Set up containers for ibm,client-architecture-support negotiated options
>       */
> diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> index bac450ffff23..2569ae1bc7f8 100644
> --- a/hw/ppc/spapr_irq.c
> +++ b/hw/ppc/spapr_irq.c
> @@ -12,6 +12,7 @@
>  #include "qemu/error-report.h"
>  #include "qapi/error.h"
>  #include "hw/ppc/spapr.h"
> +#include "hw/ppc/spapr_xive.h"
>  #include "hw/ppc/xics.h"
>  #include "sysemu/kvm.h"
>  
> @@ -91,7 +92,7 @@ error:
>  }
>  
>  static void spapr_irq_init_xics(sPAPRMachineState *spapr, int nr_irqs,
> -                                Error **errp)
> +                                int nr_servers, Error **errp)
>  {
>      MachineState *machine = MACHINE(spapr);
>      Error *local_err = NULL;
> @@ -204,10 +205,122 @@ sPAPRIrq spapr_irq_xics = {
>      .print_info  = spapr_irq_print_info_xics,
>  };
>  
> + /*
> + * XIVE IRQ backend.
> + */
> +static sPAPRXive *spapr_xive_create(sPAPRMachineState *spapr,
> +                                    const char *type_xive, int nr_irqs,
> +                                    int nr_servers, Error **errp)
> +{
> +    sPAPRXive *xive;
> +    Error *local_err = NULL;
> +    Object *obj;
> +    uint32_t nr_ends = nr_servers << 3; /* 8 priority ENDs per CPU */
> +    int i;
> +
> +    obj = object_new(type_xive);

What's the reason for making the type a parameter, rather than just
using the #define here.

> +    object_property_set_int(obj, nr_irqs, "nr-irqs", &error_abort);
> +    object_property_set_int(obj, nr_ends, "nr-ends", &error_abort);

This is still within the sPAPR code, and you have a pointer to the
MachineState, so I don't see why you could't just derive nr_irqs and
nr_servers from that, rather than having them passed in.

> +    object_property_set_bool(obj, true, "realized", &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return NULL;
> +    }
> +    qdev_set_parent_bus(DEVICE(obj), sysbus_get_default());

Whereas the XiveSource and XiveRouter I think make more sense as
"device components" rather than SysBusDevice subclasses, I think it
*does* make sense for the PAPR-XIVE object to be a full fledged
SysBusDevice.

And for that reason, I think it makes more sense to create it with
qdev_create(), which should avoid having to manually fiddle with the
parent bus.

> +    xive = SPAPR_XIVE(obj);
> +
> +    /* Enable the CPU IPIs */
> +    for (i = 0; i < nr_servers; ++i) {
> +        spapr_xive_irq_enable(xive, SPAPR_IRQ_IPI + i, false);

This comment possibly belonged on an earlier patch.  I don't love the
"..._enable" name - to me that suggests something runtime rather than
configuration time.  A better option isn't quickly occurring to me
though :/.

> +    }
> +
> +    return xive;
> +}
> +
> +static void spapr_irq_init_xive(sPAPRMachineState *spapr, int nr_irqs,
> +                                int nr_servers, Error **errp)
> +{
> +    MachineState *machine = MACHINE(spapr);
> +    Error *local_err = NULL;
> +
> +    /* KVM XIVE support */
> +    if (kvm_enabled()) {
> +        if (machine_kernel_irqchip_required(machine)) {
> +            error_setg(errp, "kernel_irqchip requested. no XIVE support");
> +            return;
> +        }
> +    }
> +
> +    /* QEMU XIVE support */
> +    spapr->xive = spapr_xive_create(spapr, TYPE_SPAPR_XIVE, nr_irqs, nr_servers,
> +                                    &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +}
> +
> +static int spapr_irq_claim_xive(sPAPRMachineState *spapr, int irq, bool lsi,
> +                                Error **errp)
> +{
> +    if (!spapr_xive_irq_enable(spapr->xive, irq, lsi)) {
> +        error_setg(errp, "IRQ %d is invalid", irq);
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +static void spapr_irq_free_xive(sPAPRMachineState *spapr, int irq, int num)
> +{
> +    int i;
> +
> +    for (i = irq; i < irq + num; ++i) {
> +        spapr_xive_irq_disable(spapr->xive, i);
> +    }
> +}
> +
> +static qemu_irq spapr_qirq_xive(sPAPRMachineState *spapr, int irq)
> +{
> +    return spapr_xive_qirq(spapr->xive, irq);
> +}
> +
> +static void spapr_irq_print_info_xive(sPAPRMachineState *spapr,
> +                                      Monitor *mon)
> +{
> +    CPUState *cs;
> +
> +    CPU_FOREACH(cs) {
> +        PowerPCCPU *cpu = POWERPC_CPU(cs);
> +
> +        xive_tctx_pic_print_info(XIVE_TCTX(cpu->intc), mon);
> +    }
> +
> +    spapr_xive_pic_print_info(spapr->xive, mon);

Any reason the info dumping routines are split into two?

> +}
> +
> +/*
> + * XIVE uses the full IRQ number space. Set it to 8K to be compatible
> + * with XICS.
> + */
> +
> +#define SPAPR_IRQ_XIVE_NR_IRQS     0x2000
> +#define SPAPR_IRQ_XIVE_NR_MSIS     (SPAPR_IRQ_XIVE_NR_IRQS - SPAPR_IRQ_MSI)
> +
> +sPAPRIrq spapr_irq_xive = {
> +    .nr_irqs     = SPAPR_IRQ_XIVE_NR_IRQS,
> +    .nr_msis     = SPAPR_IRQ_XIVE_NR_MSIS,
> +
> +    .init        = spapr_irq_init_xive,
> +    .claim       = spapr_irq_claim_xive,
> +    .free        = spapr_irq_free_xive,
> +    .qirq        = spapr_qirq_xive,
> +    .print_info  = spapr_irq_print_info_xive,
> +};
> +
>  /*
>   * sPAPR IRQ frontend routines for devices
>   */
> -void spapr_irq_init(sPAPRMachineState *spapr, Error **errp)
> +void spapr_irq_init(sPAPRMachineState *spapr, int nr_servers, Error **errp)
>  {
>      sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
>  
> @@ -216,7 +329,7 @@ void spapr_irq_init(sPAPRMachineState *spapr, Error **errp)
>          spapr_irq_msi_init(spapr, smc->irq->nr_msis);
>      }
>  
> -    smc->irq->init(spapr, smc->irq->nr_irqs, errp);
> +    smc->irq->init(spapr, smc->irq->nr_irqs, nr_servers, errp);
>  }
>  
>  int spapr_irq_claim(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp)

-- 
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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