Merge tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee into next/drivers

Pull "tee dynamic shm for v4.16" from Jens Wiklander:

This pull request enables dynamic shared memory support in the TEE
subsystem as a whole and in OP-TEE in particular.

Global Platform TEE specification [1] allows client applications
to register part of own memory as a shared buffer between
application and TEE. This allows fast zero-copy communication between
TEE and REE. But current implementation of TEE in Linux does not support
this feature.

Also, current implementation of OP-TEE transport uses fixed size
pre-shared buffer for all communications with OP-TEE OS. This is okay
in the most use cases. But this prevents use of OP-TEE in virtualized
environments, because:
 a) We can't share the same buffer between different virtual machines
 b) Physically contiguous memory as seen by VM can be non-contiguous
    in reality (and as seen by OP-TEE OS) due to second stage of
    MMU translation.
 c) Size of this pre-shared buffer is limited.

So, first part of this pull request adds generic register/unregister
interface to tee subsystem. The second part adds necessary features into
OP-TEE driver, so it can use not only static pre-shared buffer, but
whole RAM to communicate with OP-TEE OS.

This change is backwards compatible allowing older secure world or
user space to work with newer kernels and vice versa.

[1] https://www.globalplatform.org/specificationsdevice.asp

* tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee:
  tee: shm: inline tee_shm_get_id()
  tee: use reference counting for tee_context
  tee: optee: enable dynamic SHM support
  tee: optee: add optee-specific shared pool implementation
  tee: optee: store OP-TEE capabilities in private data
  tee: optee: add registered buffers handling into RPC calls
  tee: optee: add registered shared parameters handling
  tee: optee: add shared buffer registration functions
  tee: optee: add page list manipulation functions
  tee: optee: Update protocol definitions
  tee: shm: add page accessor functions
  tee: shm: add accessors for buffer size and page offset
  tee: add register user memory
  tee: flexible shared memory pool creation

drivers/tee/tee_core.c

@@ -54,6 +54,7 @@ static int tee_open(struct inode *inode, struct file *filp)
 		goto err;
 	}
 
+	kref_init(&ctx->refcount);
 	ctx->teedev = teedev;
 	INIT_LIST_HEAD(&ctx->list_shm);
 	filp->private_data = ctx;
@@ -68,19 +69,40 @@ err:
 	return rc;
 }
 
+void teedev_ctx_get(struct tee_context *ctx)
+{
+	if (ctx->releasing)
+		return;
+
+	kref_get(&ctx->refcount);
+}
+
+static void teedev_ctx_release(struct kref *ref)
+{
+	struct tee_context *ctx = container_of(ref, struct tee_context,
+					       refcount);
+	ctx->releasing = true;
+	ctx->teedev->desc->ops->release(ctx);
+	kfree(ctx);
+}
+
+void teedev_ctx_put(struct tee_context *ctx)
+{
+	if (ctx->releasing)
+		return;
+
+	kref_put(&ctx->refcount, teedev_ctx_release);
+}
+
+static void teedev_close_context(struct tee_context *ctx)
+{
+	tee_device_put(ctx->teedev);
+	teedev_ctx_put(ctx);
+}
+
 static int tee_release(struct inode *inode, struct file *filp)
 {
-	struct tee_context *ctx = filp->private_data;
-	struct tee_device *teedev = ctx->teedev;
-	struct tee_shm *shm;
-
-	ctx->teedev->desc->ops->release(ctx);
-	mutex_lock(&ctx->teedev->mutex);
-	list_for_each_entry(shm, &ctx->list_shm, link)
-		shm->ctx = NULL;
-	mutex_unlock(&ctx->teedev->mutex);
-	kfree(ctx);
-	tee_device_put(teedev);
+	teedev_close_context(filp->private_data);
 	return 0;
 }
 
@@ -114,8 +136,6 @@ static int tee_ioctl_shm_alloc(struct tee_context *ctx,
 	if (data.flags)
 		return -EINVAL;
 
-	data.id = -1;
-
 	shm = tee_shm_alloc(ctx, data.size, TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
 	if (IS_ERR(shm))
 		return PTR_ERR(shm);
@@ -138,6 +158,43 @@ static int tee_ioctl_shm_alloc(struct tee_context *ctx,
 	return ret;
 }
 
+static int
+tee_ioctl_shm_register(struct tee_context *ctx,
+		       struct tee_ioctl_shm_register_data __user *udata)
+{
+	long ret;
+	struct tee_ioctl_shm_register_data data;
+	struct tee_shm *shm;
+
+	if (copy_from_user(&data, udata, sizeof(data)))
+		return -EFAULT;
+
+	/* Currently no input flags are supported */
+	if (data.flags)
+		return -EINVAL;
+
+	shm = tee_shm_register(ctx, data.addr, data.length,
+			       TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED);
+	if (IS_ERR(shm))
+		return PTR_ERR(shm);
+
+	data.id = shm->id;
+	data.flags = shm->flags;
+	data.length = shm->size;
+
+	if (copy_to_user(udata, &data, sizeof(data)))
+		ret = -EFAULT;
+	else
+		ret = tee_shm_get_fd(shm);
+	/*
+	 * When user space closes the file descriptor the shared memory
+	 * should be freed or if tee_shm_get_fd() failed then it will
+	 * be freed immediately.
+	 */
+	tee_shm_put(shm);
+	return ret;
+}
+
 static int params_from_user(struct tee_context *ctx, struct tee_param *params,
 			    size_t num_params,
 			    struct tee_ioctl_param __user *uparams)
@@ -578,6 +635,8 @@ static long tee_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return tee_ioctl_version(ctx, uarg);
 	case TEE_IOC_SHM_ALLOC:
 		return tee_ioctl_shm_alloc(ctx, uarg);
+	case TEE_IOC_SHM_REGISTER:
+		return tee_ioctl_shm_register(ctx, uarg);
 	case TEE_IOC_OPEN_SESSION:
 		return tee_ioctl_open_session(ctx, uarg);
 	case TEE_IOC_INVOKE: