Re: [PATCH v4 6/8] vfio/mdev: Add iommu place holders in mdev_device
From: Lu Baolu
Date: Tue Nov 06 2018 - 20:51:28 EST
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@xxxxxxxxxxxxxxx> 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@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Cc: Liu Yi L <yi.l.liu@xxxxxxxxx>
Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
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.
Sorry for the confusion.
Best regards,
Lu Baolu