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

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Date:   Mon, 23 Jul 2018 04:44:02 +0000
From:   "Liu, Yi L" <yi.l.liu@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.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 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.

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;
> +	}
> +
>  	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