Re: [Qemu-devel] [PATCH 14/25] spapr: push the XIVE EQ data in OS event queue

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

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On Thu, Nov 23, 2017 at 02:29:44PM +0100, Cédric Le Goater wrote:
> If a triggered event is let through, the Event Queue data defined in the
> associated IVE is pushed in the in-memory event queue. The latter is a
> circular buffer provided by the OS using the H_INT_SET_QUEUE_CONFIG hcall,
> one per server and priority couple. It is composed of Event Queue entries
> which are 4 bytes long, the first bit being a 'generation' bit and the 31
> following bits the EQ Data field.
> 
> The EQ Data field provides a way to set an invariant logical event source
> number for an IRQ. It is set with the H_INT_SET_SOURCE_CONFIG hcall.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  hw/intc/spapr_xive.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
> 
> diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
> index 983317a6b3f6..df14c5a88275 100644
> --- a/hw/intc/spapr_xive.c
> +++ b/hw/intc/spapr_xive.c
> @@ -193,9 +193,76 @@ static sPAPRXiveICP *spapr_xive_icp_get(sPAPRXive *xive, int server)
>      return cpu ? SPAPR_XIVE_ICP(cpu->intc) : NULL;
>  }
>  
> +static void spapr_xive_eq_push(XiveEQ *eq, uint32_t data)
> +{
> +    uint64_t qaddr_base = (((uint64_t)(eq->w2 & 0x0fffffff)) << 32) | eq->w3;
> +    uint32_t qsize = GETFIELD(EQ_W0_QSIZE, eq->w0);
> +    uint32_t qindex = GETFIELD(EQ_W1_PAGE_OFF, eq->w1);
> +    uint32_t qgen = GETFIELD(EQ_W1_GENERATION, eq->w1);
> +
> +    uint64_t qaddr = qaddr_base + (qindex << 2);
> +    uint32_t qdata = cpu_to_be32((qgen << 31) | (data & 0x7fffffff));
> +    uint32_t qentries = 1 << (qsize + 10);
> +
> +    if (dma_memory_write(&address_space_memory, qaddr, &qdata, sizeof(qdata))) {

This suggests that uint32_t data contains guest endian data, which it
generally shouldn't.  Better to use stl_be_dma() (or whatever is
appropriate for the endianness of the data field.

> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: failed to write EQ data @0x%"
> +                      HWADDR_PRIx "\n", __func__, qaddr);
> +        return;
> +    }
> +
> +    qindex = (qindex + 1) % qentries;
> +    if (qindex == 0) {
> +        qgen ^= 1;
> +        eq->w1 = SETFIELD(EQ_W1_GENERATION, eq->w1, qgen);
> +    }
> +    eq->w1 = SETFIELD(EQ_W1_PAGE_OFF, eq->w1, qindex);
> +}
> +
>  static void spapr_xive_irq(sPAPRXive *xive, int lisn)
>  {
> +    XiveIVE *ive;
> +    XiveEQ *eq;
> +    uint32_t eq_idx;
> +    uint8_t priority;
> +
> +    ive = spapr_xive_get_ive(xive, lisn);
> +    if (!ive || !(ive->w & IVE_VALID)) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid LISN %d\n", lisn);

As mentioned on other patches, I'm a little concerned by these
guest-triggerable logs.  I guess the LOG_GUEST_ERROR mask will save
us, though.

> +        return;
> +    }
>  
> +    if (ive->w & IVE_MASKED) {
> +        return;
> +    }
> +
> +    /* Find our XiveEQ */
> +    eq_idx = GETFIELD(IVE_EQ_INDEX, ive->w);
> +    eq = spapr_xive_get_eq(xive, eq_idx);
> +    if (!eq) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: No EQ for LISN %d\n", lisn);
> +        return;
> +    }
> +
> +    if (eq->w0 & EQ_W0_ENQUEUE) {
> +        spapr_xive_eq_push(eq, GETFIELD(IVE_EQ_DATA, ive->w));
> +    } else {
> +        qemu_log_mask(LOG_UNIMP, "XIVE: !ENQUEUE not implemented\n");
> +    }
> +
> +    if (!(eq->w0 & EQ_W0_UCOND_NOTIFY)) {
> +        qemu_log_mask(LOG_UNIMP, "XIVE: !UCOND_NOTIFY not implemented\n");
> +    }
> +
> +    if (GETFIELD(EQ_W6_FORMAT_BIT, eq->w6) == 0) {
> +        priority = GETFIELD(EQ_W7_F0_PRIORITY, eq->w7);
> +
> +        /* The EQ is masked. Can this happen ?  */
> +        if (priority == 0xff) {
> +            g_assert_not_reached();
> +        }
> +    } else {
> +        qemu_log_mask(LOG_UNIMP, "XIVE: w7 format1 not implemented\n");
> +    }
>  }
>  
>  /*

-- 
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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