Re: [PATCH 35/50] ppc/xive: Add xive_tctx_pipr_set() helper function

[Mike Kowal]

On 5/11/2025 10:10 PM, Nicholas Piggin wrote:
> Have xive_tctx_notify() also set the new PIPR value and rename it to
> xive_tctx_pipr_set(). This can replace the last xive_tctx_pipr_update()
> caller because it does not need to update IPB (it already sets it).

Reviewed-by: Michael Kowal<kowal@linux.ibm.com>

Thanks,  MAK


> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   hw/intc/xive.c        | 39 +++++++++++----------------------------
>   hw/intc/xive2.c       | 16 +++++++---------
>   include/hw/ppc/xive.h |  5 ++---
>   3 files changed, 20 insertions(+), 40 deletions(-)
>
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index d5dbeab6bd..4659821d4a 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -125,12 +125,16 @@ uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t 
> sig_ring)
>       return ((uint64_t)nsr << 8) | sig_regs[TM_CPPR];
>   }
>   
> -void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring, uint8_t group_level)
> +/* Change PIPR and calculate NSR and irq based on PIPR, CPPR, group */
> +void xive_tctx_pipr_set(XiveTCTX *tctx, uint8_t ring, uint8_t pipr,
> +                        uint8_t group_level)
>   {
>       uint8_t *sig_regs = xive_tctx_signal_regs(tctx, ring);
>       uint8_t *regs = &tctx->regs[ring];
>   
> -    if (sig_regs[TM_PIPR] < sig_regs[TM_CPPR]) {
> +    sig_regs[TM_PIPR] = pipr;
> +
> +    if (pipr < sig_regs[TM_CPPR]) {
>           switch (ring) {
>           case TM_QW1_OS:
>               sig_regs[TM_NSR] = TM_QW1_NSR_EO | (group_level & 0x3F);
> @@ -145,7 +149,7 @@ void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring, uint8_t 
> group_level)
>               g_assert_not_reached();
>           }
>           trace_xive_tctx_notify(tctx->cs->cpu_index, ring,
> -                               regs[TM_IPB], sig_regs[TM_PIPR],
> +                               regs[TM_IPB], pipr,
>                                  sig_regs[TM_CPPR], sig_regs[TM_NSR]);
>           qemu_irq_raise(xive_tctx_output(tctx, ring));
>       } else {
> @@ -213,29 +217,10 @@ static void xive_tctx_set_cppr(XiveTCTX *tctx, uint8_t 
> ring, uint8_t cppr)
>           }
>       }
>   
> -    sig_regs[TM_PIPR] = pipr_min;
> -
> -    /* CPPR has changed, check if we need to raise a pending exception */
> -    xive_tctx_notify(tctx, ring_min, 0);
> +    /* CPPR has changed, this may present or preclude a pending exception */
> +    xive_tctx_pipr_set(tctx, ring_min, pipr_min, 0);
>   }
>   
> -void xive_tctx_pipr_update(XiveTCTX *tctx, uint8_t ring, uint8_t priority,
> -                           uint8_t group_level)
> -{
> -    uint8_t *sig_regs = xive_tctx_signal_regs(tctx, ring);
> -    uint8_t *regs = &tctx->regs[ring];
> -
> -    if (group_level == 0) {
> -        /* VP-specific */
> -        regs[TM_IPB] |= xive_priority_to_ipb(priority);
> -        sig_regs[TM_PIPR] = xive_ipb_to_pipr(regs[TM_IPB]);
> -    } else {
> -        /* VP-group */
> -        sig_regs[TM_PIPR] = xive_priority_to_pipr(priority);
> -    }
> -    xive_tctx_notify(tctx, ring, group_level);
> - }
> -
>   static void xive_tctx_pipr_recompute_from_ipb(XiveTCTX *tctx, uint8_t ring)
>   {
>       uint8_t *sig_regs = xive_tctx_signal_regs(tctx, ring);
> @@ -244,8 +229,7 @@ static void xive_tctx_pipr_recompute_from_ipb(XiveTCTX 
> *tctx, uint8_t ring)
>       /* Does not support a presented group interrupt */
>       g_assert(!xive_nsr_indicates_group_exception(ring, sig_regs[TM_NSR]));
>   
> -    sig_regs[TM_PIPR] = xive_ipb_to_pipr(regs[TM_IPB]);
> -    xive_tctx_notify(tctx, ring, 0);
> +    xive_tctx_pipr_set(tctx, ring, xive_ipb_to_pipr(regs[TM_IPB]), 0);
>   }
>   
>   void xive_tctx_pipr_present(XiveTCTX *tctx, uint8_t ring, uint8_t priority,
> @@ -264,8 +248,7 @@ void xive_tctx_pipr_present(XiveTCTX *tctx, uint8_t ring, 
> uint8_t priority,
>       }
>       g_assert(pipr <= xive_ipb_to_pipr(regs[TM_IPB]));
>       g_assert(pipr < sig_regs[TM_PIPR]);
> -    sig_regs[TM_PIPR] = pipr;
> -    xive_tctx_notify(tctx, ring, group_level);
> +    xive_tctx_pipr_set(tctx, ring, pipr, group_level);
>   }
>   
>   /*
> diff --git a/hw/intc/xive2.c b/hw/intc/xive2.c
> index b9ee8c9e9f..8c8dab3aa2 100644
> --- a/hw/intc/xive2.c
> +++ b/hw/intc/xive2.c
> @@ -966,10 +966,10 @@ static void xive2_tctx_need_resend(Xive2Router *xrtr, 
> XiveTCTX *tctx,
>       }
>   
>       /*
> -     * Compute the PIPR based on the restored state.
> +     * Set the PIPR/NSR based on the restored state.
>        * It will raise the External interrupt signal if needed.
>        */
> -    xive_tctx_pipr_update(tctx, TM_QW1_OS, backlog_prio, backlog_level);
> +    xive_tctx_pipr_set(tctx, TM_QW1_OS, backlog_prio, backlog_level);
>   }
>   
>   /*
> @@ -1144,8 +1144,7 @@ static void xive2_tctx_set_cppr(XiveTCTX *tctx, uint8_t 
> ring, uint8_t cppr)
>               }
>   
>               /* interrupt is VP directed, pending in IPB */
> -            sig_regs[TM_PIPR] = cppr;
> -            xive_tctx_notify(tctx, ring, 0); /* Ensure interrupt is cleared */
> +            xive_tctx_pipr_set(tctx, ring, cppr, 0);
>               return;
>           } else {
>               /* CPPR was lowered, but still above PIPR. No action needed. */
> @@ -1255,11 +1254,10 @@ again:
>           pipr_min = backlog_prio;
>       }
>   
> -    /* PIPR should not be set to a value greater than CPPR */
> -    sig_regs[TM_PIPR] = (pipr_min > cppr) ? cppr : pipr_min;
> -
> -    /* CPPR has changed, check if we need to raise a pending exception */
> -    xive_tctx_notify(tctx, ring_min, group_level);
> +    if (pipr_min > cppr) {
> +        pipr_min = cppr;
> +    }
> +    xive_tctx_pipr_set(tctx, ring_min, pipr_min, group_level);
>   }
>   
>   void xive2_tm_set_hv_cppr(XivePresenter *xptr, XiveTCTX *tctx,
> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> index a3c2f50ece..2372d1014b 100644
> --- a/include/hw/ppc/xive.h
> +++ b/include/hw/ppc/xive.h
> @@ -584,12 +584,11 @@ void xive_tctx_pic_print_info(XiveTCTX *tctx, GString 
> *buf);
>   Object *xive_tctx_create(Object *cpu, XivePresenter *xptr, Error **errp);
>   void xive_tctx_reset(XiveTCTX *tctx);
>   void xive_tctx_destroy(XiveTCTX *tctx);
> -void xive_tctx_pipr_update(XiveTCTX *tctx, uint8_t ring, uint8_t priority,
> -                           uint8_t group_level);
> +void xive_tctx_pipr_set(XiveTCTX *tctx, uint8_t ring, uint8_t priority,
> +                        uint8_t group_level);
>   void xive_tctx_pipr_present(XiveTCTX *tctx, uint8_t ring, uint8_t priority,
>                               uint8_t group_level);
>   void xive_tctx_reset_signal(XiveTCTX *tctx, uint8_t ring);
> -void xive_tctx_notify(XiveTCTX *tctx, uint8_t ring, uint8_t group_level);
>   uint64_t xive_tctx_accept(XiveTCTX *tctx, uint8_t ring);
>   
>   /*