[RFC 08/20] vfio/pci: Add VFIO_DEVICE_BIND_IOMMUFD

Liu Yi L
2021-09-19T06:42:45Z

This patch adds VFIO_DEVICE_BIND_IOMMUFD for userspace to bind the vfio
device to an iommufd. No VFIO_DEVICE_UNBIND_IOMMUFD interface is provided
because it's implicitly done when the device fd is closed.

In concept a vfio device can be bound to multiple iommufds, each hosting
a subset of I/O address spaces attached by this device. However as a
starting point (matching current vfio), only one I/O address space is
supported per vfio device. It implies one device can only be attached
to one iommufd at this point.

Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
---
drivers/vfio/pci/Kconfig | 1 +
drivers/vfio/pci/vfio_pci.c | 72 ++++++++++++++++++++++++++++-
drivers/vfio/pci/vfio_pci_private.h | 8 ++++
include/uapi/linux/vfio.h | 30 ++++++++++++
4 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index 5e2e1b9a9fd3..3abfb098b4dc 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -5,6 +5,7 @@ config VFIO_PCI
depends on MMU
select VFIO_VIRQFD
select IRQ_BYPASS_MANAGER
+ select IOMMUFD
help
Support for the PCI VFIO bus driver. This is required to make
use of PCI drivers using the VFIO framework.
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 145addde983b..20006bb66430 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -552,6 +552,16 @@ static void vfio_pci_release(struct vfio_device *core_vdev)
vdev->req_trigger = NULL;
}
mutex_unlock(&vdev->igate);
+
+ mutex_lock(&vdev->videv_lock);
+ if (vdev->videv) {
+ struct vfio_iommufd_device *videv = vdev->videv;
+
+ vdev->videv = NULL;
+ iommufd_unbind_device(videv->idev);
+ kfree(videv);
+ }
+ mutex_unlock(&vdev->videv_lock);
}

mutex_unlock(&vdev->reflck->lock);
@@ -780,7 +790,66 @@ static long vfio_pci_ioctl(struct vfio_device *core_vdev,
container_of(core_vdev, struct vfio_pci_device, vdev);
unsigned long minsz;

- if (cmd == VFIO_DEVICE_GET_INFO) {
+ if (cmd == VFIO_DEVICE_BIND_IOMMUFD) {
+ struct vfio_device_iommu_bind_data bind_data;
+ unsigned long minsz;
+ struct iommufd_device *idev;
+ struct vfio_iommufd_device *videv;
+
+ /*
+ * Reject the request if the device is already opened and
+ * attached to a container.
+ */
+ if (vfio_device_in_container(core_vdev))
+ return -ENOTTY;
+
+ minsz = offsetofend(struct vfio_device_iommu_bind_data, dev_cookie);
+
+ if (copy_from_user(&bind_data, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (bind_data.argsz < minsz ||
+ bind_data.flags || bind_data.iommu_fd < 0)
+ return -EINVAL;
+
+ mutex_lock(&vdev->videv_lock);
+ /*
+ * Allow only one iommufd per device until multiple
+ * address spaces (e.g. vSVA) support is introduced
+ * in the future.
+ */
+ if (vdev->videv) {
+ mutex_unlock(&vdev->videv_lock);
+ return -EBUSY;
+ }
+
+ idev = iommufd_bind_device(bind_data.iommu_fd,
+ &vdev->pdev->dev,
+ bind_data.dev_cookie);
+ if (IS_ERR(idev)) {
+ mutex_unlock(&vdev->videv_lock);
+ return PTR_ERR(idev);
+ }
+
+ videv = kzalloc(sizeof(*videv), GFP_KERNEL);
+ if (!videv) {
+ iommufd_unbind_device(idev);
+ mutex_unlock(&vdev->videv_lock);
+ return -ENOMEM;
+ }
+ videv->idev = idev;
+ videv->iommu_fd = bind_data.iommu_fd;
+ /*
+ * A security context has been established. Unblock
+ * user access.
+ */
+ if (atomic_read(&vdev->block_access))
+ atomic_set(&vdev->block_access, 0);
+ vdev->videv = videv;
+ mutex_unlock(&vdev->videv_lock);
+
+ return 0;
+ } else if (cmd == VFIO_DEVICE_GET_INFO) {
struct vfio_device_info info;
struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
unsigned long capsz;
@@ -2031,6 +2100,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
mutex_init(&vdev->vma_lock);
INIT_LIST_HEAD(&vdev->vma_list);
init_rwsem(&vdev->memory_lock);
+ mutex_init(&vdev->videv_lock);

ret = vfio_pci_reflck_attach(vdev);
if (ret)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index f12012e30b53..bd784accac35 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -14,6 +14,7 @@
#include <linux/types.h>
#include <linux/uuid.h>
#include <linux/notifier.h>
+#include <linux/iommufd.h>

#ifndef VFIO_PCI_PRIVATE_H
#define VFIO_PCI_PRIVATE_H
@@ -99,6 +100,11 @@ struct vfio_pci_mmap_vma {
struct list_head vma_next;
};

+struct vfio_iommufd_device {
+ struct iommufd_device *idev;
+ int iommu_fd;
+};
+
struct vfio_pci_device {
struct vfio_device vdev;
struct pci_dev *pdev;
@@ -144,6 +150,8 @@ struct vfio_pci_device {
struct list_head vma_list;
struct rw_semaphore memory_lock;
atomic_t block_access;
+ struct mutex videv_lock;
+ struct vfio_iommufd_device *videv;
};

#define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index ef33ea002b0b..c902abd60339 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -190,6 +190,36 @@ struct vfio_group_status {

/* --------------- IOCTLs for DEVICE file descriptors --------------- */

+/*
+ * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 19,
+ * struct vfio_device_iommu_bind_data)
+ *
+ * Bind a vfio_device to the specified iommufd
+ *
+ * The user should provide a device cookie when calling this ioctl. The
+ * cookie is later used in iommufd for capability query, iotlb invalidation
+ * and I/O fault handling.
+ *
+ * User is not allowed to access the device before the binding operation
+ * is completed.
+ *
+ * Unbind is automatically conducted when device fd is closed.
+ *
+ * Input parameters:
+ * - iommu_fd;
+ * - dev_cookie;
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_iommu_bind_data {
+ __u32 argsz;
+ __u32 flags;
+ __s32 iommu_fd;
+ __u64 dev_cookie;
+};
+
+#define VFIO_DEVICE_BIND_IOMMUFD _IO(VFIO_TYPE, VFIO_BASE + 19)
+
/**
* VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
* struct vfio_device_info)
--
2.25.1