On 2012-03-27 23:31, Alex Williamson wrote:
> On Tue, 2012-03-27 at 17:00 -0400, Jason Baron wrote:
>> The current 'kvm_init_irq_routing()' doesn't set up the gsi bitmap
>> correctly, and as a consequence pins max_gsi to 32 when it really
>> should be 1024. I ran into this limitation while testing pci
>> passthrough, where I consistently would get -ENOSPACE return from
>> kvm_get_irq_route_gsi() in assigned_dev_update_msix_mmio().
>>
>> Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
>> ---
>> kvm-all.c | 4 ++--
>> qemu-kvm.c | 2 +-
>> 2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/kvm-all.c b/kvm-all.c
>> index ab88c7c..7d602af 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -873,9 +873,9 @@ static void kvm_init_irq_routing(KVMState *s)
>> unsigned int gsi_bits, i;
>>
>> /* Round up so we can search ints using ffs */
>> - gsi_bits = (gsi_count + 31) / 32;
>> + gsi_bits = ALIGN(gsi_count, 32);
>> s->used_gsi_bitmap = g_malloc0(gsi_bits / 8);
>
> I think the above is all that's needed (it actually used to be this,
> then got broken in 84b058d). But if we do this:
>
>> - s->max_gsi = gsi_bits;
>> + s->max_gsi = gsi_count;
>
> Then we'll hit this assert from the code immediately below where we're
> marking over-allocated bits as already used if we actually did a
> round-up:
>
> static void set_gsi(KVMState *s, unsigned int gsi)
> {
> assert(gsi < s->max_gsi);
>
> Sorry, I had forgotten about this pre-allocation trick to avoid
> returning > gsi_count when we talked about this.
Oh, indeed. That's slightly ugly, gsi_max remains misnamed.
Let's just drop the overeager asserts and keep the number of bitmap
words in KVMState. That's what we really need for doing the work.
Jan
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