vfio: Add VFIO_DEVICE_BIND_IOMMUFD

This adds ioctl for userspace to bind device cdev fd to iommufd.

    VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA
			      control provided by the iommufd. open_device
			      op is called after bind_iommufd op.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230718135551.6592-23-yi.l.liu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index bf1032d001077c86ba2d564941c824694d97d344..f40784dd55617ba67cf20447042064116b5d1a2f 100644 (file)
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2023 Intel Corporation.
  */
 #include <linux/vfio.h>
+#include <linux/iommufd.h>
 
 #include "vfio.h"
 
@@ -45,6 +46,112 @@ err_put_registration:
        return ret;
 }
 
+static void vfio_df_get_kvm_safe(struct vfio_device_file *df)
+{
+       spin_lock(&df->kvm_ref_lock);
+       vfio_device_get_kvm_safe(df->device, df->kvm);
+       spin_unlock(&df->kvm_ref_lock);
+}
+
+long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+                               struct vfio_device_bind_iommufd __user *arg)
+{
+       struct vfio_device *device = df->device;
+       struct vfio_device_bind_iommufd bind;
+       unsigned long minsz;
+       int ret;
+
+       static_assert(__same_type(arg->out_devid, df->devid));
+
+       minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
+
+       if (copy_from_user(&bind, arg, minsz))
+               return -EFAULT;
+
+       if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
+               return -EINVAL;
+
+       /* BIND_IOMMUFD only allowed for cdev fds */
+       if (df->group)
+               return -EINVAL;
+
+       ret = vfio_device_block_group(device);
+       if (ret)
+               return ret;
+
+       mutex_lock(&device->dev_set->lock);
+       /* one device cannot be bound twice */
+       if (df->access_granted) {
+               ret = -EINVAL;
+               goto out_unlock;
+       }
+
+       df->iommufd = iommufd_ctx_from_fd(bind.iommufd);
+       if (IS_ERR(df->iommufd)) {
+               ret = PTR_ERR(df->iommufd);
+               df->iommufd = NULL;
+               goto out_unlock;
+       }
+
+       /*
+        * Before the device open, get the KVM pointer currently
+        * associated with the device file (if there is) and obtain
+        * a reference.  This reference is held until device closed.
+        * Save the pointer in the device for use by drivers.
+        */
+       vfio_df_get_kvm_safe(df);
+
+       ret = vfio_df_open(df);
+       if (ret)
+               goto out_put_kvm;
+
+       ret = copy_to_user(&arg->out_devid, &df->devid,
+                          sizeof(df->devid)) ? -EFAULT : 0;
+       if (ret)
+               goto out_close_device;
+
+       device->cdev_opened = true;
+       /*
+        * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
+        * read/write/mmap
+        */
+       smp_store_release(&df->access_granted, true);
+       mutex_unlock(&device->dev_set->lock);
+       return 0;
+
+out_close_device:
+       vfio_df_close(df);
+out_put_kvm:
+       vfio_device_put_kvm(device);
+       iommufd_ctx_put(df->iommufd);
+       df->iommufd = NULL;
+out_unlock:
+       mutex_unlock(&device->dev_set->lock);
+       vfio_device_unblock_group(device);
+       return ret;
+}
+
+void vfio_df_unbind_iommufd(struct vfio_device_file *df)
+{
+       struct vfio_device *device = df->device;
+
+       /*
+        * In the time of close, there is no contention with another one
+        * changing this flag.  So read df->access_granted without lock
+        * and no smp_load_acquire() is ok.
+        */
+       if (!df->access_granted)
+               return;
+
+       mutex_lock(&device->dev_set->lock);
+       vfio_df_close(df);
+       vfio_device_put_kvm(device);
+       iommufd_ctx_put(df->iommufd);
+       device->cdev_opened = false;
+       mutex_unlock(&device->dev_set->lock);
+       vfio_device_unblock_group(device);
+}
+
 static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
 {
        return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index c2aa6538259285051bd4d065fb111fbc6fbc0896..b6d4ba1ef2b81e0d23e0f78b5e40fef3cffa0837 100644 (file)
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device *device)
 }
 
 int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
+long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+                               struct vfio_device_bind_iommufd __user *arg);
+void vfio_df_unbind_iommufd(struct vfio_device_file *df);
 int vfio_cdev_init(struct class *device_class);
 void vfio_cdev_cleanup(void);
 #else
@@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct inode *inode,
        return 0;
 }
 
+static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
+                                             struct vfio_device_bind_iommufd __user *arg)
+{
+       return -ENOTTY;
+}
+
+static inline void vfio_df_unbind_iommufd(struct vfio_device_file *df)
+{
+}
+
 static inline int vfio_cdev_init(struct class *device_class)
 {
        return 0;

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index a2744cb64c6df1e43bc98ff585c12d569b9b520d..9fdf93ff17cf16a92c26d98234d06e6939ed9aa3 100644 (file)
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -575,6 +575,8 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 
        if (df->group)
                vfio_df_group_close(df);
+       else
+               vfio_df_unbind_iommufd(df);
 
        vfio_device_put_registration(device);
 
@@ -1149,6 +1151,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
        void __user *uptr = (void __user *)arg;
        int ret;
 
+       if (cmd == VFIO_DEVICE_BIND_IOMMUFD)
+               return vfio_df_ioctl_bind_iommufd(df, uptr);
+
        /* Paired with smp_store_release() following vfio_df_open() */
        if (!smp_load_acquire(&df->access_granted))
                return -EINVAL;

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e0069f26488dfc0a664dfe4feba8e42045386e80..d6228c839c449a5b3021ce19bd01ed0b6cf5b986 100644 (file)
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -64,8 +64,9 @@ struct vfio_device {
        void (*put_kvm)(struct kvm *kvm);
 #if IS_ENABLED(CONFIG_IOMMUFD)
        struct iommufd_device *iommufd_device;
-       bool iommufd_attached;
+       u8 iommufd_attached:1;
 #endif
+       u8 cdev_opened:1;
 };
 
 /**
@@ -168,7 +169,7 @@ vfio_iommufd_get_dev_id(struct vfio_device *vdev, struct iommufd_ctx *ictx)
 
 static inline bool vfio_device_cdev_opened(struct vfio_device *device)
 {
-       return false;
+       return device->cdev_opened;
 }
 
 /**

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 4c3d548e9c9660e6f6c609e87c5122ac483e4fa0..098946b23e8646ddf7e20b68e7ea93fc164eb21c 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -897,6 +897,33 @@ struct vfio_device_feature {
 
 #define VFIO_DEVICE_FEATURE            _IO(VFIO_TYPE, VFIO_BASE + 17)
 
+/*
+ * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 18,
+ *                                struct vfio_device_bind_iommufd)
+ * @argsz:      User filled size of this data.
+ * @flags:      Must be 0.
+ * @iommufd:    iommufd to bind.
+ * @out_devid:  The device id generated by this bind. devid is a handle for
+ *              this device/iommufd bond and can be used in IOMMUFD commands.
+ *
+ * Bind a vfio_device to the specified iommufd.
+ *
+ * User is restricted from accessing the device before the binding operation
+ * is completed.  Only allowed on cdev fds.
+ *
+ * Unbind is automatically conducted when device fd is closed.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_bind_iommufd {
+       __u32           argsz;
+       __u32           flags;
+       __s32           iommufd;
+       __u32           out_devid;
+};
+
+#define VFIO_DEVICE_BIND_IOMMUFD       _IO(VFIO_TYPE, VFIO_BASE + 18)
+
 /*
  * Provide support for setting a PCI VF Token, which is used as a shared
  * secret between PF and VF drivers.  This feature may only be set on a