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

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Message-ID: <BN9PR11MB5276EE81D21EC5E4156EB7D58C3E2@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Wed, 11 Dec 2024 08:21:42 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Nicolin Chen <nicolinc@...dia.com>, "jgg@...dia.com" <jgg@...dia.com>,
	"will@...nel.org" <will@...nel.org>
CC: "corbet@....net" <corbet@....net>, "joro@...tes.org" <joro@...tes.org>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"robin.murphy@....com" <robin.murphy@....com>, "dwmw2@...radead.org"
	<dwmw2@...radead.org>, "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
	"shuah@...nel.org" <shuah@...nel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "iommu@...ts.linux.dev"
	<iommu@...ts.linux.dev>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kselftest@...r.kernel.org"
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	<smostafa@...gle.com>, "ddutile@...hat.com" <ddutile@...hat.com>, "Liu, Yi L"
	<yi.l.liu@...el.com>
Subject: RE: [PATCH v2 13/13] iommu/arm-smmu-v3: Report IRQs that belong to
 devices attached to vIOMMU

> From: Nicolin Chen <nicolinc@...dia.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.

> @@ -1779,33 +1779,6 @@ static int arm_smmu_handle_evt(struct
> arm_smmu_device *smmu, u64 *evt)
>  		return -EOPNOTSUPP;
>  	}
> 
> -	if (!(evt[1] & EVTQ_1_STALL))
> -		return -EOPNOTSUPP;
> -
> -	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]);
> -	}
> -
>  	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?

> +	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);
> +	} else {
> +		/* Unhandled events should be pinned */
> +		ret = -EFAULT;
> +	}
> +	up_read(&master->vmaster_rwsem);
>  out_unlock:
>  	mutex_unlock(&smmu->streams_mutex);
>  	return ret;
> --
> 2.43.0