linux-kernel - Re: [RFC PATCH 01/10] iommu/vt-d: Get iommu device for a mediated device

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Date:   Tue, 24 Jul 2018 10:06:44 +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 01/10] iommu/vt-d: Get iommu device for a mediated
 device

Hi Yi,

Thank you for reviewing my patch.

On 07/23/2018 12:44 PM, Liu, Yi L wrote:
> Hi Baolu,
>
> Per my understanding, the subject is not accurate. I think this patch is
> to get parent device structure for a mediate device instead of iommu
> device. This may be misleading for reviewers.

Please check below.

>
> Thanks,
> Yi Liu
>
>> From: Lu Baolu [mailto:baolu.lu@...ux.intel.com]
>> Sent: Sunday, July 22, 2018 2:09 PM
>>
>> This patch adds the support to get the iommu device for a mediated device. The
>> assumption is that each mediated device is a minimal assignable set of a physical PCI
>> device. Hence, we should use the iommu device of the parent PCI device to manage
>> the translation.
>>
>> 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 |  6 ++++++  drivers/iommu/intel-pasid.h | 16
>> ++++++++++++++++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index
>> 7d198ea..fc3ac1c 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -767,6 +767,12 @@ static struct intel_iommu *device_to_iommu(struct device
>> *dev, u8 *bus, u8 *devf
>>  	if (iommu_dummy(dev))
>>  		return NULL;
>>
>> +	if (dev_is_mdev(dev)) {
>> +		dev = dev_mdev_parent(dev);
>> +		if (WARN_ON(!dev_is_pci(dev)))
>> +			return NULL;
>> +	}
>> +

This gets the parent of a mediated device. And an iommu device will be
found which services the parent device. A mediated device should in the
same iommu scope as its parent.

Best regards,
Lu Baolu

>>  	if (dev_is_pci(dev)) {
>>  		struct pci_dev *pf_pdev;
>>
>> diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h index
>> 518df72..46cde66 100644
>> --- a/drivers/iommu/intel-pasid.h
>> +++ b/drivers/iommu/intel-pasid.h
>> @@ -35,6 +35,22 @@ struct pasid_table {
>>  	struct list_head	dev;		/* device list */
>>  };
>>
>> +static inline bool dev_is_mdev(struct device *dev) {
>> +	if (!dev)
>> +		return false;
>> +
>> +	return !strcmp(dev->bus->name, "mdev"); }
>> +
>> +static inline struct device *dev_mdev_parent(struct device *dev) {
>> +	if (WARN_ON(!dev_is_mdev(dev)))
>> +		return NULL;
>> +
>> +	return dev->parent;
>> +}
>> +
>>  extern u32 intel_pasid_max_id;
>>  int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp);  void
>> intel_pasid_free_id(int pasid);
>> --
>> 2.7.4
>