Re: [Qemu-devel] [PATCH 10/27] ppc/xive: Make XIVE generate the proper interrupt types

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

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On Wed, Mar 06, 2019 at 09:50:15AM +0100, Cédric Le Goater wrote:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> It should be generic Hypervisor Virtualization interrupts for HV
> directed rings and traditional External Interrupts for the OS directed
> ring.
> 
> Don't generate anything for the user ring as it isn't actually
> supported.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/xive.h |  3 ++-
>  hw/intc/xive.c        | 22 +++++++++++++++++++---
>  2 files changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> index c4f27742ca09..6b89dc7679f9 100644
> --- a/include/hw/ppc/xive.h
> +++ b/include/hw/ppc/xive.h
> @@ -313,7 +313,8 @@ typedef struct XiveTCTX {
>      DeviceState parent_obj;
>  
>      CPUState    *cs;
> -    qemu_irq    output;
> +    qemu_irq    hv_output;
> +    qemu_irq    os_output;
>  
>      uint8_t     regs[XIVE_TM_RING_COUNT * XIVE_TM_RING_SIZE];
>  } XiveTCTX;
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index a0b87001da25..237e7b256dc0 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -61,13 +61,28 @@ static uint8_t exception_mask(uint8_t ring)
>      }
>  }
>  
> +static qemu_irq xive_tctx_output(XiveTCTX *tctx, uint8_t ring)
> +{
> +        switch (ring) {
> +        case TM_QW0_USER:
> +                return 0; /* Not supported */

IIUC hitting this case would indicate a code error, not a guest error,
in which case g_assert_not_reached() would be more appropriate that
returning 0.

Return "0" is kind of weird.  qemu_irq is actually a pointer so this
is really returning NULL.  But I don't think most things that handle
qemu_irq expect them to be NULL, so it's likely that this will just
crash further on.

Apart from that, LGTM.

> +        case TM_QW1_OS:
> +                return tctx->os_output;
> +        case TM_QW2_HV_POOL:
> +        case TM_QW3_HV_PHYS:
> +                return tctx->hv_output;
> +        default:
> +                return 0;
> +        }
> +}
> +
>  static uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t ring)
>  {
>      uint8_t *regs = &tctx->regs[ring];
>      uint8_t nsr = regs[TM_NSR];
>      uint8_t mask = exception_mask(ring);
>  
> -    qemu_irq_lower(tctx->output);
> +    qemu_irq_lower(xive_tctx_output(tctx, ring));
>  
>      if (regs[TM_NSR] & mask) {
>          uint8_t cppr = regs[TM_PIPR];
> @@ -100,7 +115,7 @@ static void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring)
>          default:
>              g_assert_not_reached();
>          }
> -        qemu_irq_raise(tctx->output);
> +        qemu_irq_raise(xive_tctx_output(tctx, ring));
>      }
>  }
>  
> @@ -546,7 +561,8 @@ static void xive_tctx_realize(DeviceState *dev, Error **errp)
>      env = &cpu->env;
>      switch (PPC_INPUT(env)) {
>      case PPC_FLAGS_INPUT_POWER9:
> -        tctx->output = env->irq_inputs[POWER9_INPUT_INT];
> +        tctx->hv_output = env->irq_inputs[POWER9_INPUT_HINT];
> +        tctx->os_output = env->irq_inputs[POWER9_INPUT_INT];
>          break;
>  
>      default:

-- 
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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