linux-kernel - RE: [PATCH v8 10/10] iommu/vt-d: Add iotlb flush for nested domain

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Message-ID: <BN9PR11MB527696416E2B1F33900007968C9EA@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Thu, 28 Dec 2023 07:11:48 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: "Liu, Yi L" <yi.l.liu@...el.com>, "joro@...tes.org" <joro@...tes.org>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>, "jgg@...dia.com"
	<jgg@...dia.com>, "robin.murphy@....com" <robin.murphy@....com>,
	"baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>
CC: "cohuck@...hat.com" <cohuck@...hat.com>, "eric.auger@...hat.com"
	<eric.auger@...hat.com>, "nicolinc@...dia.com" <nicolinc@...dia.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>, "mjrosato@...ux.ibm.com"
	<mjrosato@...ux.ibm.com>, "chao.p.peng@...ux.intel.com"
	<chao.p.peng@...ux.intel.com>, "yi.y.sun@...ux.intel.com"
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	<shameerali.kolothum.thodi@...wei.com>, "lulu@...hat.com" <lulu@...hat.com>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>, "Duan,
 Zhenzhong" <zhenzhong.duan@...el.com>, "joao.m.martins@...cle.com"
	<joao.m.martins@...cle.com>, "Zeng, Xin" <xin.zeng@...el.com>, "Zhao, Yan Y"
	<yan.y.zhao@...el.com>, "j.granados@...sung.com" <j.granados@...sung.com>
Subject: RE: [PATCH v8 10/10] iommu/vt-d: Add iotlb flush for nested domain

> From: Liu, Yi L <yi.l.liu@...el.com>
> Sent: Thursday, December 28, 2023 12:14 AM
> 
> 
> +static void nested_flush_pasid_iotlb(struct intel_iommu *iommu,
> +				     struct dmar_domain *domain, u64 addr,
> +				     unsigned long npages, bool ih)
> +{
> +	u16 did = domain_id_iommu(domain, iommu);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&domain->lock, flags);
> +	if (!list_empty(&domain->devices))
> +		qi_flush_piotlb(iommu, did, IOMMU_NO_PASID, addr,
> +				npages, ih, NULL);

Not sure the check of domain->devices makes sense here. The outer
loop is xa_for_each(&domain->iommu_array, i, info) which, if found,
then implies certain devices behind this iommu must be attached to
this domain.

I wonder whether it's clearer to remove this function and just call
qi_flush_piotlb() from intel_nested_flush_cache().

> +
> +	/*
> +	 * Invalidation queue error (i.e. IQE) will not be reported to user
> +	 * as it's caused only by driver internal bug.
> +	 */

here lack of:

	*error = 0;

> +	if (fault & DMA_FSTS_ICE)
> +		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ICE;
> +	if (fault & DMA_FSTS_ITE)
> +		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ITE;
> +}
> +