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Re: [PATCH for-5.0 v5 01/23] ppc/xive: Record the IPB in the associated
From: |
Greg Kurz |
Subject: |
Re: [PATCH for-5.0 v5 01/23] ppc/xive: Record the IPB in the associated NVT |
Date: |
Mon, 18 Nov 2019 16:44:11 +0100 |
On Fri, 15 Nov 2019 17:24:14 +0100
Cédric Le Goater <address@hidden> wrote:
> When an interrupt can not be presented to a vCPU, because it is not
> running on any of the HW treads, the XIVE presenter updates the
> Interrupt Pending Buffer register of the associated XIVE NVT
> structure. This is only done if backlog is activated in the END but
> this is generally the case.
>
> The current code assumes that the fields of the NVT structure is
> architected with the same layout of the thread interrupt context
> registers. Fix this assumption and define an offset for the IPB
> register backup value in the NVT.
>
Does this fix a visible bug in the powernv machine ? If so,
maybe worth describing the symptoms.
Anyway, this seems conforment to the XIVE spec I have, so FWIW:
Reviewed-by: Greg Kurz <address@hidden>
> Signed-off-by: Cédric Le Goater <address@hidden>
> ---
> 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 3d472e29c858..177663d2b43e 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -1607,14 +1607,21 @@ 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);
>
> /*