Re: [Qemu-devel] [RFC PATCH 09/26] ppc/xive: add an overall memory region for the ESBs

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2017-07-24 at 14:49 +1000, David Gibson wrote:
> On Wed, Jul 05, 2017 at 07:13:22PM +0200, Cédric Le Goater wrote:
> > Each source adds its own ESB mempry region to the overall ESB memory
> > region of the controller. It will be mapped in the CPU address space
> > when XIVE is activated.
> > 
> > The default mapping address for the ESB memory region is the same one
> > used on baremetal.
> > 
> > Signed-off-by: Cédric Le Goater <clg@kaod.org>
> > ---
> >  hw/intc/xive-internal.h |  5 +++++
> >  hw/intc/xive.c          | 44 +++++++++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 48 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/intc/xive-internal.h b/hw/intc/xive-internal.h
> > index 8e755aa88a14..c06be823aad0 100644
> > --- a/hw/intc/xive-internal.h
> > +++ b/hw/intc/xive-internal.h
> > @@ -98,6 +98,7 @@ struct XIVE {
> >      SysBusDevice parent;
> >  
> >      /* Properties */
> > +    uint32_t     chip_id;
> 
> So there is a XIVE object per chip.  How does this work on PAPR?  One
> logical chip/XIVE, or something more complex?

One global XIVE for PAPR. For the MMIOs, the way it works is that:

 - For MMIOs pertaining to a specific interrupt or queue, there's an H-
call that will return the proper "guest physical" address. For qemu
with KVM we'll have to probably create a single chunk of qemu address
space (a single mem region) that contains individual pages mapped with
MAP_FIXED originating from the different HW bits, we still need to sort
out how exactly we'll do that in practice.

 - For the TIMA (the presentation MMIOs), those are always at the same
physical address for everybody (so for a guest it's a single memory
region we'll map to that physical address), the HW "knows" which HW
thread is talking to it (and the hypervisor tells the HW which vcpu is
running on a given HW thread at a given point in time). That address is
obtained from the device-tree

> >      uint32_t     nr_targets;
> >  
> >      /* IRQ number allocator */
> > @@ -111,6 +112,10 @@ struct XIVE {
> >      void         *sbe;
> >      XiveIVE      *ivt;
> >      XiveEQ       *eqdt;
> > +
> > +    /* ESB and TIMA memory location */
> > +    hwaddr       vc_base;
> > +    MemoryRegion esb_iomem;
> >  };
> >  
> >  void xive_reset(void *dev);
> > diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> > index 8f8bb8b787bd..a1cb87a07b76 100644
> > --- a/hw/intc/xive.c
> > +++ b/hw/intc/xive.c
> > @@ -312,6 +312,7 @@ static void xive_ics_realize(ICSState *ics, Error **errp)
> >      XiveICSState *xs = ICS_XIVE(ics);
> >      Object *obj;
> >      Error *err = NULL;
> > +    XIVE *x;
> 
> I don't really like just 'x' for a context variable like this (as
> opposed to a temporary).
> 
> >  
> >      obj = object_property_get_link(OBJECT(xs), "xive", &err);
> >      if (!obj) {
> > @@ -319,7 +320,7 @@ static void xive_ics_realize(ICSState *ics, Error **errp)
> >                     __func__, error_get_pretty(err));
> >          return;
> >      }
> > -    xs->xive = XIVE(obj);
> > +    x = xs->xive = XIVE(obj);
> >  
> >      if (!ics->nr_irqs) {
> >          error_setg(errp, "Number of interrupts needs to be greater 0");
> > @@ -338,6 +339,11 @@ static void xive_ics_realize(ICSState *ics, Error **errp)
> >                            "xive.esb",
> >                            (1ull << xs->esb_shift) * ICS_BASE(xs)->nr_irqs);
> >  
> > +    /* Install the ESB memory region in the overall one */
> > +    memory_region_add_subregion(&x->esb_iomem,
> > +                                ICS_BASE(xs)->offset * (1 << xs->esb_shift),
> > +                                &xs->esb_iomem);
> > +
> >      qemu_register_reset(xive_ics_reset, xs);
> >  }
> >  
> > @@ -375,6 +381,32 @@ static const TypeInfo xive_ics_info = {
> >   */
> >  #define MAX_HW_IRQS_ENTRIES (8 * 1024)
> >  
> > +/* VC BAR contains set translations for the ESBs and the EQs. */
> > +#define VC_BAR_DEFAULT   0x10000000000ull
> > +#define VC_BAR_SIZE      0x08000000000ull
> > +
> > +#define P9_MMIO_BASE     0x006000000000000ull
> > +#define P9_CHIP_BASE(id) (P9_MMIO_BASE | (0x40000000000ull * (uint64_t) (id)))
> 
> chip-based MMIO addresses leaking into the PAPR model seems like it
> might not be what you want
> 
> > +static uint64_t 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 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 xive_esb_default_ops = {
> > +    .read = xive_esb_default_read,
> > +    .write = xive_esb_default_write,
> > +    .endianness = DEVICE_BIG_ENDIAN,
> > +};
> >  
> >  void xive_reset(void *dev)
> >  {
> > @@ -435,10 +467,20 @@ static void xive_realize(DeviceState *dev, Error **errp)
> >      x->eqdt = g_malloc0(x->nr_targets * XIVE_EQ_PRIORITY_COUNT *
> >                          sizeof(XiveEQ));
> >  
> > +    /* VC BAR. That's the full window but we will only map the
> > +     * subregions in use. */
> > +    x->vc_base = (hwaddr)(P9_CHIP_BASE(x->chip_id) | VC_BAR_DEFAULT);
> > +
> > +    /* install default memory region handlers to log bogus access */
> > +    memory_region_init_io(&x->esb_iomem, NULL, &xive_esb_default_ops,
> > +                          NULL, "xive.esb", VC_BAR_SIZE);
> > +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &x->esb_iomem);
> > +
> >      qemu_register_reset(xive_reset, dev);
> >  }
> >  
> >  static Property xive_properties[] = {
> > +    DEFINE_PROP_UINT32("chip-id", XIVE, chip_id, 0),
> >      DEFINE_PROP_UINT32("nr-targets", XIVE, nr_targets, 0),
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> 
>