Re: [PATCH v2 13/13] iommu/arm-smmu-v3: Report IRQs that belong to devices attached to vIOMMU

[Nicolin Chen <nicolinc@nvidia.com>]

On Wed, Dec 11, 2024 at 08:21:42AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Wednesday, December 4, 2024 6:10 AM
> > 
> > +
> > +/**
> > + * struct iommu_virq_arm_smmuv3 - ARM SMMUv3 Virtual IRQ
> > + *                                (IOMMU_VIRQ_TYPE_ARM_SMMUV3)
> > + * @evt: 256-bit ARM SMMUv3 Event record, little-endian.
> > + *
> > + * StreamID field reports a virtual device ID. To receive a virtual IRQ for a
> > + * device, a vDEVICE must be allocated via IOMMU_VDEVICE_ALLOC.
> > + */
> 
> similar to what's provided for iommu_hw_info_arm_smmuv3, it'd be
> good to refer to a section in smmu spec for bit definitions.

Ack.

> >  	mutex_lock(&smmu->streams_mutex);
> >  	master = arm_smmu_find_master(smmu, sid);
> >  	if (!master) {
> > @@ -1813,7 +1786,40 @@ static int arm_smmu_handle_evt(struct
> > arm_smmu_device *smmu, u64 *evt)
> >  		goto out_unlock;
> >  	}
> > 
> > -	ret = iommu_report_device_fault(master->dev, &fault_evt);
> > +	down_read(&master->vmaster_rwsem);
> 
> this lock is not required if event is EVTQ_1_STALL?

No. It only protects master->vmaster. Perhaps I can rewrite this
piece to exclude the lock from the EVTQ_1_STALL chunk.

> > +	if (evt[1] & EVTQ_1_STALL) {
> > +		if (evt[1] & EVTQ_1_RnW)
> > +			perm |= IOMMU_FAULT_PERM_READ;
> > +		else
> > +			perm |= IOMMU_FAULT_PERM_WRITE;
> > +
> > +		if (evt[1] & EVTQ_1_InD)
> > +			perm |= IOMMU_FAULT_PERM_EXEC;
> > +
> > +		if (evt[1] & EVTQ_1_PnU)
> > +			perm |= IOMMU_FAULT_PERM_PRIV;
> > +
> > +		flt->type = IOMMU_FAULT_PAGE_REQ;
> > +		flt->prm = (struct iommu_fault_page_request){
> > +			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
> > +			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
> > +			.perm = perm,
> > +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> > +		};
> > +
> > +		if (ssid_valid) {
> > +			flt->prm.flags |=
> > IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
> > +			flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
> > +		}
> > +
> > +		ret = iommu_report_device_fault(master->dev, &fault_evt);
> > +	} else if (master->vmaster && !(evt[1] & EVTQ_1_S2)) {
> > +		ret = arm_vmaster_report_event(master->vmaster, evt);

Thanks
Nic