linux-kernel - Re: [RFC PATCH 03/10] iommu/vt-d: Allocate groups for mediated devices

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Message-ID: <5B568D5B.5050606@linux.intel.com>
Date:   Tue, 24 Jul 2018 10:22:19 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     "Liu, Yi L" <yi.l.liu@...el.com>, Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kirti Wankhede <kwankhede@...dia.com>
Cc:     "Raj, Ashok" <ashok.raj@...el.com>,
        "Kumar, Sanjay K" <sanjay.k.kumar@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "Sun, Yi Y" <yi.y.sun@...el.com>,
        "peterx@...hat.com" <peterx@...hat.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [RFC PATCH 03/10] iommu/vt-d: Allocate groups for mediated
 devices

Hi,

On 07/23/2018 12:44 PM, Liu, Yi L wrote:
>> From: Lu Baolu [mailto:baolu.lu@...ux.intel.com]
>> Sent: Sunday, July 22, 2018 2:09 PM
>>
>> With the Intel IOMMU supporting PASID granularity isolation and protection, a
>> mediated device could be isolated and protected by an IOMMU unit. We need to
>> allocate a new group instead of a PCI group.
> Existing vfio mdev framework also allocates an iommu group for mediate device.
>
> mdev_probe()
>   |_ mdev_attach_iommu()
>        |_ iommu_group_alloc()

When external components ask iommu to allocate a group for a device,
it will call pci_device_group in Intel IOMMU driver's @device_group
callback. In another word, current Intel IOMMU driver doesn't aware
the mediated device and treat all devices as PCI ones. This patch
extends the @device_group call back to make it aware of a mediated
device.

Best regards,
Lu Baolu

>
> IMHO, this patch actually do a wrapper to the group allocation API. The reason is: it
> is not necessary to apply the group allocation rules when the allocation is for mediated
> device. Instead, just allocate a new one for it. :)
>
> Thanks,
> Yi Liu
>> Cc: Ashok Raj <ashok.raj@...el.com>
>> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
>> Cc: Kevin Tian <kevin.tian@...el.com>
>> Cc: Liu Yi L <yi.l.liu@...el.com>
>> Signed-off-by: Sanjay Kumar <sanjay.k.kumar@...el.com>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> ---
>>  drivers/iommu/intel-iommu.c | 13 ++++++++++++-
>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index
>> 3ede34a..57ccfc4 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -5276,6 +5276,17 @@ static void intel_iommu_put_resv_regions(struct device
>> *dev,
>>  	}
>>  }
>>
>> +static struct iommu_group *intel_iommu_device_group(struct device *dev)
>> +{
>> +	if (dev_is_pci(dev))
>> +		return pci_device_group(dev);
>> +
>> +	if (dev_is_mdev(dev))
>> +		return iommu_group_alloc();
>> +
>> +	return ERR_PTR(-EINVAL);
>> +}
>> +
>>  #ifdef CONFIG_INTEL_IOMMU_SVM
>>  int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev
>> *sdev)  { @@ -5370,7 +5381,7 @@ const struct iommu_ops intel_iommu_ops = {
>>  	.remove_device		= intel_iommu_remove_device,
>>  	.get_resv_regions	= intel_iommu_get_resv_regions,
>>  	.put_resv_regions	= intel_iommu_put_resv_regions,
>> -	.device_group		= pci_device_group,
>> +	.device_group		= intel_iommu_device_group,
>>  	.pgsize_bitmap		= INTEL_IOMMU_PGSIZES,
>>  };
>>
>> --
>> 2.7.4
>