Re: [Qemu-devel] [RFC PATCH v2 07/21] ppc/xive: add MMIO handlers for the XIVE interrupt sources

["Cédric Le Goater" <clg@kaod.org>]

>> +/*
>> + * XIVE Interrupt Source MMIOs
>> + */
>> +static uint64_t spapr_xive_esb_read(void *opaque, hwaddr addr, unsigned size)
>> +{
>> +    sPAPRXive *xive = SPAPR_XIVE(opaque);
>> +    uint32_t offset = addr & 0xF00;
>> +    uint32_t srcno = addr >> xive->esb_shift;
>> +    XiveIVE *ive;
>> +    uint64_t ret = -1;
>> +
>> +    ive = spapr_xive_get_ive(xive, srcno);
>> +    if (!ive || !(ive->w & IVE_VALID))  {
>> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: invalid LISN %d\n", srcno);
>> +        goto out;
> 
> Since there's a whole (4k) page for each source, I wonder if we should
> actually map each one as a separate MMIO region to allow us to tweak
> the mappings more flexibly
yes we could have a subregion for each source. In that case, 
we should also handle IVE_VALID properly. That will require 
a specific XIVE allocator which was difficult to do while
keeping the compatibility with XICS for migration and CAS.


C.