Re: [Qemu-devel] [PATCH v2 07/17] ppc/xive: Provide silent escalation support

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

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On Thu, Jul 18, 2019 at 01:54:10PM +0200, Cédric Le Goater wrote:
> When the 's' bit is set the escalation is said to be 'silent' or
> 'silent/gather'. In such configuration, the notification sequence is
> skipped and only the escalation sequence is performed. This is used to
> configure all the EQs of a vCPU to escalate on a single EQ which will
> then target the hypervisor.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/xive_regs.h | 2 ++
>  hw/intc/xive.c             | 8 ++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
> index 5d02ccfeff16..69af326ebf2c 100644
> --- a/include/hw/ppc/xive_regs.h
> +++ b/include/hw/ppc/xive_regs.h
> @@ -209,6 +209,8 @@ typedef struct XiveEND {
>  #define xive_end_is_escalate(end) (be32_to_cpu((end)->w0) & END_W0_ESCALATE_CTL)
>  #define xive_end_is_uncond_escalation(end)              \
>      (be32_to_cpu((end)->w0) & END_W0_UNCOND_ESCALATE)
> +#define xive_end_is_silent_escalation(end)              \
> +    (be32_to_cpu((end)->w0) & END_W0_SILENT_ESCALATE)
>  
>  static inline uint64_t xive_end_qaddr(XiveEND *end)
>  {
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index c2e7e2d4c9a9..8ea97ac231a4 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -1463,6 +1463,13 @@ static void xive_router_end_notify(XiveRouter *xrtr, uint8_t end_blk,
>          xive_router_write_end(xrtr, end_blk, end_idx, &end, 1);
>      }
>  
> +    /*
> +     * When the END is silent, we skip the notification part.
> +     */
> +    if (xive_end_is_silent_escalation(&end)) {
> +        goto do_escalation;

I don't love this use of goto, but I'll take it for now.

> +    }
> +
>      /*
>       * The W7 format depends on the F bit in W6. It defines the type
>       * of the notification :
> @@ -1542,6 +1549,7 @@ static void xive_router_end_notify(XiveRouter *xrtr, uint8_t end_blk,
>           */
>      }
>  
> +do_escalation:
>      /*
>       * If activated, escalate notification using the ESe PQ bits and
>       * the EAS in w4-5

-- 
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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