linux-kernel - Re: [PATCH 18/18] iommu/vt-d: Add svm/sva invalidate function

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Date:   Tue, 9 Apr 2019 10:43:39 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Andriy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>, Liu@...le.fi.intel.com,
        Yi L <yi.l.liu@...ux.intel.com>, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH 18/18] iommu/vt-d: Add svm/sva invalidate function

On Tue, 9 Apr 2019 17:57:12 +0300
Andriy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On Mon, Apr 08, 2019 at 04:59:33PM -0700, Jacob Pan wrote:
> > When Shared Virtual Address (SVA) is enabled for a guest OS via
> > vIOMMU, we need to provide invalidation support at IOMMU API and
> > driver level. This patch adds Intel VT-d specific function to
> > implement iommu passdown invalidate API for shared virtual address.
> > 
> > The use case is for supporting caching structure invalidation
> > of assigned SVM capable devices. Emulated IOMMU exposes queue
> > invalidation capability and passes down all descriptors from the
> > guest to the physical IOMMU.
> > 
> > The assumption is that guest to host device ID mapping should be
> > resolved prior to calling IOMMU driver. Based on the device handle,
> > host IOMMU driver can replace certain fields before submit to the
> > invalidation queue.  
> 
> > +static int intel_iommu_sva_invalidate(struct iommu_domain *domain,
> > +		struct device *dev, struct
> > iommu_cache_invalidate_info *inv_info) +{
> > +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +	struct device_domain_info *info;
> > +	struct intel_iommu *iommu;
> > +	unsigned long flags;
> > +	int cache_type;
> > +	u8 bus, devfn;
> > +	u16 did, sid;
> > +	int ret = 0;
> > +	u64 granu;
> > +	u64 size;
> > +
> > +	if (!inv_info || !dmar_domain ||
> > +		inv_info->version !=
> > IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
> > +		return -EINVAL;
> > +
> > +	iommu = device_to_iommu(dev, &bus, &devfn);
> > +	if (!iommu)
> > +		return -ENODEV;
> > +  
> 
> > +	if (!dev || !dev_is_pci(dev))
> > +		return -ENODEV;  
> 
> How dev is used in above call? Can be dev NULL there optional and
> give non-NULL iommu?
> 
Good catch, dev cannot be NULL. I will move the check before
device_to_iommu().
> > +		switch (1 << cache_type) {  
> 
> BIT() ?
> 
> > +		case IOMMU_CACHE_INV_TYPE_IOTLB:
> > +			if (size && (inv_info->addr_info.addr &
> > ((1 << (VTD_PAGE_SHIFT + size)) - 1))) {  
> 
> BIT() ?
> 
Sounds good for the two BITs.

Thanks
> > +				pr_err("Address out of range,
> > 0x%llx, size order %llu\n",
> > +					inv_info->addr_info.addr,
> > size);
> > +				ret = -ERANGE;
> > +				goto out_unlock;
> > +			}
> > +
> > +			qi_flush_piotlb(iommu, did,
> > mm_to_dma_pfn(inv_info->addr_info.addr),
> > +					inv_info->addr_info.pasid,
> > +					size, granu);
> > +
> > +			/*
> > +			 * Always flush device IOTLB if ATS is
> > enabled since guest
> > +			 * vIOMMU exposes CM = 1, no device IOTLB
> > flush will be passed
> > +			 * down. REVISIT: cannot assume Linux guest
> > +			 */
> > +			if (info->ats_enabled) {
> > +				qi_flush_dev_piotlb(iommu, sid,
> > info->pfsid,
> > +
> > inv_info->addr_info.pasid, info->ats_qdep,
> > +
> > inv_info->addr_info.addr, size,
> > +						granu);
> > +			}
> > +			break;
> > +		case IOMMU_CACHE_INV_TYPE_DEV_IOTLB:
> > +			if (info->ats_enabled) {
> > +				qi_flush_dev_piotlb(iommu, sid,
> > info->pfsid,
> > +
> > inv_info->addr_info.pasid, info->ats_qdep,
> > +
> > inv_info->addr_info.addr, size,
> > +						granu);
> > +			} else
> > +				pr_warn("Passdown device IOTLB
> > flush w/o ATS!\n"); +
> > +			break;
> > +		case IOMMU_CACHE_INV_TYPE_PASID:
> > +			qi_flush_pasid_cache(iommu, did, granu,
> > inv_info->pasid); +
> > +			break;
> > +		default:
> > +			dev_err(dev, "Unsupported IOMMU
> > invalidation type %d\n",
> > +				cache_type);
> > +			ret = -EINVAL;
> > +		}  
> 
> > +out_unlock:
> > +	spin_unlock(&iommu->lock);
> > +	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +
> > +	return ret;
> > +}  
> 

[Jacob Pan]