linux-kernel - Re: [PATCH 2/7] iommu/vt-d: Add blocking domain support

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Message-ID: <5e9bf515-0d3a-9c4e-69b7-820b14979f6b@linux.intel.com>
Date:   Sat, 5 Nov 2022 09:54:42 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/7] iommu/vt-d: Add blocking domain support

On 2022/11/4 10:11, Tian, Kevin wrote:
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>> Sent: Thursday, November 3, 2022 1:53 PM
>>
>> +/*
>> + * Clear the page table pointer in context or pasid table entries so that
>> + * all DMA requests without PASID from the device are blocked. If the page
>> + * table has been set, clean up the data structures.
>> + */
>> +static void device_block_translation(struct device *dev)
> 
> given this helper will be used both by existing paths and the new block
> domain, it makes more sense to have it work with existing paths first
> i.e. merging with patch3 and then add block domain after.

Yes. Sounds good.

> 
>> +{
>> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +	struct intel_iommu *iommu = info->iommu;
>> +	unsigned long flags;
>> +
>> +	if (!dev_is_real_dma_subdevice(dev)) {
>> +		if (sm_supported(iommu))
>> +			intel_pasid_tear_down_entry(iommu, dev,
>> +						    PASID_RID2PASID, false);
> 
> Since commit 4140d77a aliases devices don't share pasid table,
> which implies that pci_for_each_dma_alias() is required as did
> in domain_context_clear().

The PCI alias devices have already been covered by the iommu group
concept in the iommu core. On the contrary, I've been thinking about
retiring pci_for_each_dma_alias() in domain_context_clear().



> 
>> +		else
>> +			domain_context_clear(info);
>> +	}
>> +
>> +	if (!info->domain)
>> +		return;
>> +
>> +	spin_lock_irqsave(&info->domain->lock, flags);
>> +	list_del(&info->link);
>> +	spin_unlock_irqrestore(&info->domain->lock, flags);
>> +
>> +	domain_detach_iommu(info->domain, iommu);
>> +	info->domain = NULL;
>> +}
>> +

Best regards,
baolu