Hi Jean,
On 27.02.2017 20:54, Jean-Philippe Brucker wrote:
Add two new ioctl for VFIO devices. VFIO_DEVICE_BIND_TASK creates a bond
between a device and a process address space, identified by a
device-specific ID named PASID. This allows the device to target DMA
transactions at the process virtual addresses without a need for mapping
and unmapping buffers explicitly in the IOMMU. The process page tables are
shared with the IOMMU, and mechanisms such as PCI ATS/PRI may be used to
handle faults. VFIO_DEVICE_UNBIND_TASK removed a bond identified by a
PASID.
Also add a capability flag in device info to detect whether the system and
the device support SVM.
Users need to specify the state of a PASID when unbinding, with flags
VFIO_PASID_RELEASE_FLUSHED and VFIO_PASID_RELEASE_CLEAN. Even for PCI,
PASID invalidation is specific to each device and only partially covered
by the specification:
* Device must have an implementation-defined mechanism for stopping the
use of a PASID. When this mechanism finishes, the device has stopped
issuing transactions for this PASID and all transactions for this PASID
have been flushed to the IOMMU.
* Device may either wait for all outstanding PRI requests for this PASID
to finish, or issue a Stop Marker message, a barrier that separates PRI
requests affecting this instance of the PASID from PRI requests
affecting the next instance. In the first case, we say that the PASID is
"clean", in the second case it is "flushed" (and the IOMMU has to wait
for the Stop Marker before reassigning the PASID.)
We expect similar distinctions for platform devices. Ideally there should
be a callback for each PCI device, allowing the IOMMU to ask the device to
stop using a PASID. When the callback returns, the PASID is either flushed
or clean and the return value tells which.
For the moment I don't know how to implement this callback for PCI, so if
the user forgets to call unbind with either "clean" or "flushed", the
PASID is never reused. For platform devices, it might be simpler to
implement since we could associate an invalidate_pasid callback to a DT
compatible string, as is currently done for reset.
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
drivers/vfio/pci/vfio_pci.c | 24 ++++++++++
drivers/vfio/vfio.c | 104 ++++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/vfio.h | 55 +++++++++++++++++++++++
3 files changed, 183 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 324c52e3a1a4..3d7733f94891 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -22,6 +22,7 @@
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/pci.h>
+#include <linux/pci-ats.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/types.h>
@@ -623,6 +624,26 @@ int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
return 0;
}
[...]
kfree(device);
@@ -1622,6 +1651,75 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
return 0;
}
+static long vfio_svm_ioctl(struct vfio_device *device, unsigned int cmd,
+ unsigned long arg)
+{
+ int ret;
+ unsigned long minsz;
+
+ struct vfio_device_svm svm;
+ struct vfio_task *vfio_task;
+
+ minsz = offsetofend(struct vfio_device_svm, pasid);
+
+ if (copy_from_user(&svm, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (svm.argsz < minsz)
+ return -EINVAL;
+
+ if (cmd == VFIO_DEVICE_BIND_TASK) {
+ struct task_struct *task = current;
+
+ ret = iommu_bind_task(device->dev, task, &svm.pasid, 0, NULL);
+ if (ret)
+ return ret;
+
+ vfio_task = kzalloc(sizeof(*vfio_task), GFP_KERNEL);
+ if (!vfio_task) {
+ iommu_unbind_task(device->dev, svm.pasid,
+ IOMMU_PASID_CLEAN);
+ return -ENOMEM;
+ }
+
+ vfio_task->pasid = svm.pasid;
+
+ mutex_lock(&device->tasks_lock);
+ list_add(&vfio_task->list, &device->tasks);
+ mutex_unlock(&device->tasks_lock);
+
+ } else {
+ int flags = 0;
+
+ if (svm.flags & ~(VFIO_SVM_PASID_RELEASE_FLUSHED |
+ VFIO_SVM_PASID_RELEASE_CLEAN))
+ return -EINVAL;
+
+ if (svm.flags & VFIO_SVM_PASID_RELEASE_FLUSHED)
+ flags = IOMMU_PASID_FLUSHED;
+ else if (svm.flags & VFIO_SVM_PASID_RELEASE_CLEAN)
+ flags = IOMMU_PASID_CLEAN;
+
+ mutex_lock(&device->tasks_lock);
+ list_for_each_entry(vfio_task, &device->tasks, list) {
+ if (vfio_task->pasid != svm.pasid)
+ continue;
+
+ ret = iommu_unbind_task(device->dev, svm.pasid, flags);
+ if (ret)
+ dev_warn(device->dev, "failed to unbind PASID %u\n",
+ vfio_task->pasid);
+
+ list_del(&vfio_task->list);
+ kfree(vfio_task);
Please use list_for_each_entry_safe.
Thanks,
Tomasz
