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Date: Fri, 16 Nov 2018 09:20:48 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Kirti Wankhede <kwankhede@...dia.com>,
Alex Williamson <alex.williamson@...hat.com>
Cc: baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw2@...radead.org>, ashok.raj@...el.com,
sanjay.k.kumar@...el.com, jacob.jun.pan@...el.com,
kevin.tian@...el.com,
Jean-Philippe Brucker <jean-philippe.brucker@....com>,
yi.l.liu@...el.com, yi.y.sun@...el.com, peterx@...hat.com,
tiwei.bie@...el.com, Zeng Xin <xin.zeng@...el.com>,
iommu@...ts.linux-foundation.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCH v4 6/8] vfio/mdev: Add iommu place holders in mdev_device
Hi,
On 11/16/18 5:31 AM, Kirti Wankhede wrote:
>
>
> On 11/7/2018 7:18 AM, Lu Baolu wrote:
>> Hi Alex,
>>
>> On 11/7/18 7:53 AM, Alex Williamson wrote:
>>> On Mon, 5 Nov 2018 15:34:06 +0800
>>> Lu Baolu <baolu.lu@...ux.intel.com> wrote:
>>>
>>>> A parent device might create different types of mediated
>>>> devices. For example, a mediated device could be created
>>>> by the parent device with full isolation and protection
>>>> provided by the IOMMU. One usage case could be found on
>>>> Intel platforms where a mediated device is an assignable
>>>> subset of a PCI, the DMA requests on behalf of it are all
>>>> tagged with a PASID. Since IOMMU supports PASID-granular
>>>> translations (scalable mode in vt-d 3.0), this mediated
>>>> device could be individually protected and isolated by an
>>>> IOMMU.
>>>>
>>>> This patch adds two new members in struct mdev_device:
>>>> * iommu_device
>>>> - This, if set, indicates that the mediated device could
>>>> be fully isolated and protected by IOMMU via attaching
>>>> an iommu domain to this device. If empty, it indicates
>>>> using vendor defined isolation.
>>>>
>>>> * iommu_domain
>>>> - This is a place holder for an iommu domain. A domain
>>>> could be store here for later use once it has been
>>>> attached to the iommu_device of this mdev.
>>>>
>>>> Below helpers are added to set and get above iommu device
>>>> and iommu domain pointers.
>>>>
>>>> * mdev_set/get_iommu_device(dev, iommu_device)
>>>> - Set or get the iommu device which represents this mdev
>>>> in IOMMU's device scope. Drivers don't need to set the
>>>> iommu device if it uses vendor defined isolation.
>>>>
>>>> * mdev_set/get_iommu_domain(domain)
>>>> - A iommu domain which has been attached to the iommu
>>>> device in order to protect and isolate the mediated
>>>> device will be kept in the mdev data structure and
>>>> could be retrieved later.
>>>>
>>>> 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>
>>>> Suggested-by: Kevin Tian <kevin.tian@...el.com>
>>>> Suggested-by: Alex Williamson <alex.williamson@...hat.com>
>>>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>>>> ---
>>>> drivers/vfio/mdev/mdev_core.c | 36 ++++++++++++++++++++++++++++++++
>>>> drivers/vfio/mdev/mdev_private.h | 2 ++
>>>> include/linux/mdev.h | 23 ++++++++++++++++++++
>>>> 3 files changed, 61 insertions(+)
>>>>
>>>> diff --git a/drivers/vfio/mdev/mdev_core.c
>>>> b/drivers/vfio/mdev/mdev_core.c
>>>> index 0212f0ee8aea..5119809225c5 100644
>>>> --- a/drivers/vfio/mdev/mdev_core.c
>>>> +++ b/drivers/vfio/mdev/mdev_core.c
>>>> @@ -390,6 +390,42 @@ int mdev_device_remove(struct device *dev, bool
>>>> force_remove)
>>>> return 0;
>>>> }
>>>> +int mdev_set_iommu_device(struct device *dev, struct device
>>>> *iommu_device)
>>>> +{
>>>> + struct mdev_device *mdev = to_mdev_device(dev);
>>>> +
>>>> + mdev->iommu_device = iommu_device;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_set_iommu_device);
>>>> +
>>>> +struct device *mdev_get_iommu_device(struct device *dev)
>>>> +{
>>>> + struct mdev_device *mdev = to_mdev_device(dev);
>>>> +
>>>> + return mdev->iommu_device;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_get_iommu_device);
>>>> +
>>>> +int mdev_set_iommu_domain(struct device *dev, void *domain)
>>>> +{
>>>> + struct mdev_device *mdev = to_mdev_device(dev);
>>>> +
>>>> + mdev->iommu_domain = domain;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_set_iommu_domain);
>>>> +
>>>> +void *mdev_get_iommu_domain(struct device *dev)
>>>> +{
>>>> + struct mdev_device *mdev = to_mdev_device(dev);
>>>> +
>>>> + return mdev->iommu_domain;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_get_iommu_domain);
>>>> +
>>>> static int __init mdev_init(void)
>>>> {
>>>> return mdev_bus_register();
>>>> diff --git a/drivers/vfio/mdev/mdev_private.h
>>>> b/drivers/vfio/mdev/mdev_private.h
>>>> index b5819b7d7ef7..c01518068e84 100644
>>>> --- a/drivers/vfio/mdev/mdev_private.h
>>>> +++ b/drivers/vfio/mdev/mdev_private.h
>>>> @@ -34,6 +34,8 @@ struct mdev_device {
>>>> struct list_head next;
>>>> struct kobject *type_kobj;
>>>> bool active;
>>>> + struct device *iommu_device;
>>>> + void *iommu_domain;
>>>> };
>>>> #define to_mdev_device(dev) container_of(dev, struct
>>>> mdev_device, dev)
>>>> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
>>>> index b6e048e1045f..c46777d3e568 100644
>>>> --- a/include/linux/mdev.h
>>>> +++ b/include/linux/mdev.h
>>>> @@ -14,6 +14,29 @@
>>>> #define MDEV_H
>>>> struct mdev_device;
>>>> +struct iommu_domain;
>>>> +
>>>> +/*
>>>> + * Called by the parent device driver to set the PCI device which
>>>> represents
>>>
>>> s/PCI //
>>>
>>> There is no requirement or expectation that the device is PCI.
>>>
>>
>> Fair enough.
>>
>>>> + * this mdev in iommu protection scope. By default, the iommu device
>>>> is NULL,
>>>> + * that indicates using vendor defined isolation.
>>>> + *
>>>> + * @dev: the mediated device that iommu will isolate.
>>>> + * @iommu_device: a pci device which represents the iommu for @dev.
>>>> + *
>>>> + * Return 0 for success, otherwise negative error value.
>>>> + */
>>>> +int mdev_set_iommu_device(struct device *dev, struct device
>>>> *iommu_device);
>>>> +
>>>> +struct device *mdev_get_iommu_device(struct device *dev);
>>>> +
>>>> +/*
>>>> + * Called by vfio iommu modules to save the iommu domain after a
>>>> domain being
>>>> + * attached to the mediated device.
>>>> + */
>>>> +int mdev_set_iommu_domain(struct device *dev, void *domain);
>>>> +
>>>> +void *mdev_get_iommu_domain(struct device *dev);
>>>
>>> I can't say I really understand the purpose of this, the cover letter
>>> indicates this is a placeholder, should we add it separately when we
>>> have a requirement for it?
>>
>> Oh, I am sorry that I used a wrong word. It's not a placeholder for
>> something designed for future, but adding two members that will be used
>> in the following patches. Since they will be used in anther modules
>> (like vfio_iommu), we need function interfaces to get and set them.
>>
>> mdev->iommu_device:
>> - This, if set, indicates that the mediated device could
>> be fully isolated and protected by IOMMU via attaching
>> an iommu domain to this device. If empty, it indicates
>> using vendor defined isolation.
>>
>> mdev->iommu_domain:
>> - This is used to save the pointer of an iommu domain. Once
>> a domain has been attached to the iommu_device, it should
>> be stored here.
>>
>
> I don't see mdev->iommu_domain is used anywhere in this series of patch.
> If this is not being used, then no need to save it. With that symbols
> mdev_set/get_iommu_domain(domain) are not required.
Yes. We won't use mdev->iommu_domain in this patch series. It should be
used by mdev parent driver to retrieve the default pasid of the domain.
Something like:
domain = mdev_get_iommu_domain(dev)
pasid = iommu_domain_get_attr(domain, DOMAIN_ATTR_AUXD_ID);
reg_write(pasid_reg, pasid);
I am okay if we remove mdev_set/get_iommu_domain from this patch series
and add it later when the parent driver comes.
>
> Please keep symbols mdev_set/get_iommu_device(dev, iommu_device) non-GPL
> same as other exported symbols from mdev_core module.
Yes. It will be fixed in the next version.
>
> Thanks,
> Kirti
>
Best regards,
Lu Baolu
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