Merge branch 'linus' into objtool/core, to pick up Xen dependencies

Pick up dependencies - freshly merged upstream via xen-next - before applying
dependent objtool changes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 46 insertions, 20 deletions

diff --git a/Documentation/block/capability.rst b/Documentation/block/capability.rst
deleted file mode 100644
index 2ae7f064736a..000000000000
--- a/Documentation/block/capability.rst
+++ /dev/null
@@ -1,10 +0,0 @@
-===============================
-Generic Block Device Capability
-===============================
-
-This file documents the sysfs file ``block/<disk>/capability``.
-
-``capability`` is a bitfield, printed in hexadecimal, indicating which
-capabilities a specific block device supports:
-
-.. kernel-doc:: include/linux/blkdev.h
diff --git a/Documentation/block/index.rst b/Documentation/block/index.rst
index c4c73db748a8..102953166429 100644
--- a/Documentation/block/index.rst
+++ b/Documentation/block/index.rst
@@ -10,7 +10,6 @@ Block
    bfq-iosched
    biovecs
    blk-mq
-   capability
    cmdline-partition
    data-integrity
    deadline-iosched
diff --git a/Documentation/block/ublk.rst b/Documentation/block/ublk.rst
index ba45c46cc0da..1713b2890abb 100644
--- a/Documentation/block/ublk.rst
+++ b/Documentation/block/ublk.rst
@@ -144,6 +144,43 @@ managing and controlling ublk devices with help of several control commands:
   For retrieving device info via ``ublksrv_ctrl_dev_info``. It is the server's
   responsibility to save IO target specific info in userspace.
 
+- ``UBLK_CMD_GET_DEV_INFO2``
+  Same purpose with ``UBLK_CMD_GET_DEV_INFO``, but ublk server has to
+  provide path of the char device of ``/dev/ublkc*`` for kernel to run
+  permission check, and this command is added for supporting unprivileged
+  ublk device, and introduced with ``UBLK_F_UNPRIVILEGED_DEV`` together.
+  Only the user owning the requested device can retrieve the device info.
+
+  How to deal with userspace/kernel compatibility:
+
+  1) if kernel is capable of handling ``UBLK_F_UNPRIVILEGED_DEV``
+
+    If ublk server supports ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ublk server should send ``UBLK_CMD_GET_DEV_INFO2``, given anytime
+    unprivileged application needs to query devices the current user owns,
+    when the application has no idea if ``UBLK_F_UNPRIVILEGED_DEV`` is set
+    given the capability info is stateless, and application should always
+    retrieve it via ``UBLK_CMD_GET_DEV_INFO2``
+
+    If ublk server doesn't support ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO`` is always sent to kernel, and the feature of
+    UBLK_F_UNPRIVILEGED_DEV isn't available for user
+
+  2) if kernel isn't capable of handling ``UBLK_F_UNPRIVILEGED_DEV``
+
+    If ublk server supports ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO2`` is tried first, and will be failed, then
+    ``UBLK_CMD_GET_DEV_INFO`` needs to be retried given
+    ``UBLK_F_UNPRIVILEGED_DEV`` can't be set
+
+    If ublk server doesn't support ``UBLK_F_UNPRIVILEGED_DEV``:
+
+    ``UBLK_CMD_GET_DEV_INFO`` is always sent to kernel, and the feature of
+    ``UBLK_F_UNPRIVILEGED_DEV`` isn't available for user
+
 - ``UBLK_CMD_START_USER_RECOVERY``
 
   This command is valid if ``UBLK_F_USER_RECOVERY`` feature is enabled. This
@@ -180,6 +217,15 @@ managing and controlling ublk devices with help of several control commands:
   double-write since the driver may issue the same I/O request twice. It
   might be useful to a read-only FS or a VM backend.
 
+Unprivileged ublk device is supported by passing ``UBLK_F_UNPRIVILEGED_DEV``.
+Once the flag is set, all control commands can be sent by unprivileged
+user. Except for command of ``UBLK_CMD_ADD_DEV``, permission check on
+the specified char device(``/dev/ublkc*``) is done for all other control
+commands by ublk driver, for doing that, path of the char device has to
+be provided in these commands' payload from ublk server. With this way,
+ublk device becomes container-ware, and device created in one container
+can be controlled/accessed just inside this container.
+
 Data plane
 ----------
 
@@ -254,15 +300,6 @@ with specified IO tag in the command data:
 Future development
 ==================
 
-Container-aware ublk deivice
-----------------------------
-
-ublk driver doesn't handle any IO logic. Its function is well defined
-for now and very limited userspace interfaces are needed, which is also
-well defined too. It is possible to make ublk devices container-aware block
-devices in future as Stefan Hajnoczi suggested [#stefan]_, by removing
-ADMIN privilege.
-
 Zero copy
 ---------