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

[Cédric Le Goater]

On 11/30/2017 04:49 AM, David Gibson wrote:
> 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 <address@hidden>
>> ---
>>  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.

There are no requirement on the endianness of the data field and 
it is just stored in the IVE in the hcall H_INT_SET_SOURCE_CONFIG. 
So the guest can pass whatever it likes.  

>> +        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.

I want to track 'invalid' interrupts but I haven't seen these show up 
in my tests. I agree there are a little too much and some could just 
be asserts.

Thanks,

C.

> 
>> +        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");
>> +    }
>>  }
>>  
>>  /*
>