> -----Original Message-----
> From: Nicolin Chen <[email protected]>
> Sent: 12 February 2026 17:23
> To: Eric Auger <[email protected]>
> Cc: Shameer Kolothum Thodi <[email protected]>; qemu-
> [email protected]; [email protected]; [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 v2 05/24] hw/arm/smmuv3-accel: Introduce CMDQV ops
> interface
>
> On Thu, Feb 12, 2026 at 06:05:58PM +0100, Eric Auger wrote:
> > >>> The vCMDQ path does not replace the normal accelerated SMMU
> init/reset.
> > >>> Instead, it requires additional init/reset steps on top of the regular
> > >>> accel
> flow.
> > >>>
> > >>> if (accel)
> > >>> accel_init();
> > >>>
> > >>> if (accel && cmdqv)
> > >>> cmdqv_init();
> > >>>
> > >>> So the vCMDQ logic is an extension of the accelerated mode, not a
> fallback
> > >>> or alternative implementation.
>
> Yes. And I think it makes more sense by moving cmdqv_init() into
> accel_init(), completely transparent to the common smmuv3 module
> maybe?
I have attempted that, IIRC. There is a catch there that the pci iommu_ops
needs to be set earlier(before smu_common realize) and we can only call
cmdqv_init() after the base SMMUv3 sysbus_init_mmio() and smmu_init_irq().
I need to take another if we can make that work or not.
>
> > >>> I think the later patches in the series make this clearer.
> > >>> Please let me know if you still feel the ops necessary.
> > >> do we have any way to introspect from the kernel what cmdq type we
> have,
> > >> so that we could have a cmdqv option with ON/OFF/AUTO value instead
> of
> > >> duplication cmdq option for each vendor?
> > > Looking at it again, I think we can, by calling IOMMU_GET_HW_INFO with
> all supported
> > > CMDQ types and check which one succeeds.
> >
> > then I think we should endeavour doing that. Regarding the ops, if you
> > feel that reset/init can be managed through a simple add-on code I am
> > fine with it. Maybe Cédric or Peter will have another opinion though ;-)
>
> I like that on/off/auto depending on the IOMMU_GET_HW_INFO return.
Yeah. We need to do this.
Thanks,
Shameer
