Re: [PATCH 3/9] ppc/xive: Record the IPB in the associated NVT

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

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On Mon, Oct 07, 2019 at 10:40:56AM +0200, Cédric Le Goater wrote:
> When an interrupt can not be presented to a vCPU, the XIVE presenter
> updates the Interrupt Pending Buffer of the XIVE NVT if backlog is
> activated in the END.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

This commit message doesn't really make it clear what was happening
before, which certainly looks like an update to the IPB field in the
NVT, via a different method.

Is this just a cleanup, or a fix?

> ---
>  include/hw/ppc/xive_regs.h |  1 +
>  hw/intc/xive.c             | 11 +++++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
> index 55307cd1533c..530f232b04f8 100644
> --- a/include/hw/ppc/xive_regs.h
> +++ b/include/hw/ppc/xive_regs.h
> @@ -255,6 +255,7 @@ typedef struct XiveNVT {
>          uint32_t        w2;
>          uint32_t        w3;
>          uint32_t        w4;
> +#define NVT_W4_IPB               PPC_BITMASK32(16, 23)
>          uint32_t        w5;
>          uint32_t        w6;
>          uint32_t        w7;
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index cbe4ae6c294d..2bf7b4ad7006 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -1600,14 +1600,21 @@ static void xive_router_end_notify(XiveRouter *xrtr, uint8_t end_blk,
>       * - logical server : forward request to IVPE (not supported)
>       */
>      if (xive_end_is_backlog(&end)) {
> +        uint8_t ipb;
> +
>          if (format == 1) {
>              qemu_log_mask(LOG_GUEST_ERROR,
>                            "XIVE: END %x/%x invalid config: F1 & backlog\n",
>                            end_blk, end_idx);
>              return;
>          }
> -        /* Record the IPB in the associated NVT structure */
> -        ipb_update((uint8_t *) &nvt.w4, priority);
> +        /*
> +         * Record the IPB in the associated NVT structure for later
> +         * use. The presenter will resend the interrupt when the vCPU
> +         * is dispatched again on a HW thread.
> +         */
> +        ipb = xive_get_field32(NVT_W4_IPB, nvt.w4) | priority_to_ipb(priority);
> +        nvt.w4 = xive_set_field32(NVT_W4_IPB, nvt.w4, ipb);
>          xive_router_write_nvt(xrtr, nvt_blk, nvt_idx, &nvt, 4);
>  
>          /*

-- 
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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