On 2/11/26 7:43 PM, Shameer Kolothum Thodi wrote:
>
>> -----Original Message-----
>> From: Nicolin Chen <[email protected]>
>> Sent: 11 February 2026 18:25
>> To: Eric Auger <[email protected]>
>> Cc: Shameer Kolothum Thodi <[email protected]>; qemu-
>> [email protected]; [email protected]; [email protected];
>> Nathan Chen <[email protected]>; Matt Ochs <[email protected]>;
>> Jiandi An <[email protected]>; Jason Gunthorpe <[email protected]>;
>> [email protected]; [email protected];
>> [email protected]; Krishnakant Jaju <[email protected]>
>> Subject: Re: [PATCH v5 3/5] hw/arm/smmuv3-accel: Allocate vEVENTQ for
>> accelerated SMMUv3 devices
>>
>> On Wed, Feb 11, 2026 at 07:14:40PM +0100, Eric Auger wrote:
>>> On 2/11/26 7:07 PM, Nicolin Chen wrote:
>>>> On Wed, Feb 11, 2026 at 08:34:13AM +0000, Shameer Kolothum wrote:
>>>>> For cold-plugged devices using SMMUv3 acceleration, the vIOMMU is
>>>>> created before the guest boots. In this case, the vEVENTQ is
>>>>> allocated when the guest writes to SMMU_CR0 and sets EVENTQEN = 1.
>>>> [...]
>>>>> @@ -1605,6 +1605,10 @@ static MemTxResult
>> smmu_writel(SMMUv3State *s, hwaddr offset,
>>>>> s->cr0ack = data & ~SMMU_CR0_RESERVED;
>>>>> /* in case the command queue has been enabled */
>>>>> smmuv3_cmdq_consume(s, &local_err);
>>>>> + /* Allocate vEVENTQ if EventQ is enabled and a vIOMMU is
>>>>> + available */
>>>> Nit: though it is just following smmuv3_cmdq_consume(), it'd be
>>>> likely clearer to verify the EVENTQEN in the callers.
>>>>
>>>>> + if (local_err == NULL) {
>>>> Does eventq need to rely on !local_err from cmdq?
>>> if local_err is NULL we can safely use it, no? Or maybe I miss your
>>> point. maybe test !local_err directly?
>> Point is: if local_err isn't NULL, why can't we allocate vEVENTQ?
> Technically nothing prevents that I guess.
>
> The only thing is we have to call error_report_err() if local_err != NULL
> and then set local_err == NULL before calling alloc_veventq().
Besides the implementation details about Error handle usage I think we
shall first answer the question about the relevance to allocate the
veventq in case the smmuv3_cmdq_consume() fails.
Thanks
Eric
>
> Thanks,
> Shameer
>
