[Skiboot] [PATCH v9 25/25] MPIPL: Add documentation
Vasant Hegde
hegdevasant at linux.vnet.ibm.com
Fri Jul 12 21:18:02 AEST 2019
Document MPIPL device tree and OPAL APIs.
Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth at linux.vnet.ibm.com>
---
doc/device-tree/ibm,opal/dump.rst | 37 ++++++++
doc/index.rst | 1 +
doc/mpipl.rst | 48 ++++++++++
doc/opal-api/index.rst | 6 ++
doc/opal-api/opal-cec-reboot-6-116.rst | 2 +
doc/opal-api/opal-mpipl-173-174.rst | 156 +++++++++++++++++++++++++++++++++
6 files changed, 250 insertions(+)
create mode 100644 doc/device-tree/ibm,opal/dump.rst
create mode 100644 doc/mpipl.rst
create mode 100644 doc/opal-api/opal-mpipl-173-174.rst
diff --git a/doc/device-tree/ibm,opal/dump.rst b/doc/device-tree/ibm,opal/dump.rst
new file mode 100644
index 000000000..81a09ce26
--- /dev/null
+++ b/doc/device-tree/ibm,opal/dump.rst
@@ -0,0 +1,37 @@
+.. _device-tree/ibm,opal/dump:
+
+Dump (MPIPL) Device Tree Binding
+=================================
+
+See :ref:`mpipl` for general MPIPL information.
+
+dump node
+---------
+.. code-block:: dts
+
+ dump {
+ /*
+ * Memory used by OPAL to load kernel/initrd from PNOR
+ * (KERNEL_LOAD_BASE & INITRAMFS_LOAD_BASE). This is the
+ * temporary memory used by OPAL during boot. Later Linux
+ * kernel is free to use this memory. During MPIPL boot
+ * also OPAL will overwrite this memory.
+ *
+ * OPAL will advertise these memory details to kernel.
+ * If kernel is using these memory and needs these memory
+ * content for proper dump creation, then it has to reserve
+ * destination memory to preserve these memory ranges.
+ * Also kernel should pass this detail during registration.
+ * During MPIPL firmware will take care of preserving memory
+ * and post MPIPL kernel can create proper dump.
+ */
+ fw-load-area = <0x0 0x20000000 0x0 0x8000000 0x0 0x28000000 0x0 0x8000000>;
+ /* Compatible property */
+ compatible = "ibm,opal-dump";
+ phandle = <0x98>;
+ /*
+ * This property indicates that its MPIPL boot. Kernel will use OPAL API
+ * to retrieve metadata tags and use metadata to create dump.
+ */
+ mpipl-boot
+ };
diff --git a/doc/index.rst b/doc/index.rst
index 79a5accf2..f21a658f9 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -47,6 +47,7 @@ Developer Guide and Internals
xive
imc
power-management
+ mpipl
OPAL ABI
diff --git a/doc/mpipl.rst b/doc/mpipl.rst
new file mode 100644
index 000000000..b00d336a0
--- /dev/null
+++ b/doc/mpipl.rst
@@ -0,0 +1,48 @@
+.. _mpipl:
+
+MPIPL (aka FADUMP) Overview
+===========================
+
+Memory Preserving Initial Program Load (MPIPL) is a Power feature where the
+contents of memory are preserved while the system reboots after a failure.
+This is accomplished by the firmware/OS publishing ranges of memory to be
+preserved across boots.
+
+Registration
+------------
+In the OPAL context, OPAL and host Linux communicate the memory ranges to be
+preserved via source descriptor tables in the HDAT (MDST and MDDT table inside
+SPIRAH). Host Linux can register/unregister using OPAL_MPIPL_UPDATE API (see
+:ref:`opal-api-mpipl`).
+
+Initiating dump
+---------------
+Whenever Linux crashes, it makes reboot2 OPAL call with type as MPIPL. (see
+:ref:`opal-api-cec-reboot`). Depending on sevice processor type OPAL makes
+appropriate call to initiate MPIPL. On FSP system we call `attn` instruction
+(see ``__trigger_attn()``) and on BMC system we call SBE `S0 interrupt`
+(see ``p9_sbe_terminate()``).
+
+Dump collection
+---------------
+Hostboot then re-IPLs the machine taking care to copy over contents of the
+source memory to a alternate memory locations as specified in descriptor table.
+Hostboot publishes this information in the result descriptor tables (MDRT table
+inside SPIRAH structure). The success/failure of the copy is indicated by a
+results table.
+
+SBE/Hostboot also does the requisite procedures to gather hardware register
+states for all active threads at the time of the crash.
+
+MPIPL boot
+----------
+On MPIPL boot, OPAL adds device tree entry (``/ibm,opal/dump/mpipl-boot``)
+to indicate its MPIPL boot. Kernel will use OPAL_MPIPL_QUERY_TAG API
+(:ref:`opal-api-mpipl`) to retrieve metadata tag. Kernel then uses its
+existing logic (kdump/fadump) to write out a core dump of OPAL and Linux
+kernel in a format that GDB and crash can understand.
+
+Device tree
+-----------
+We create new device tree node (``/ibm,opal/dump``) to pass dump details to Linux
+kernel from OPAL (see :ref:`device-tree/ibm,opal/dump`).
diff --git a/doc/opal-api/index.rst b/doc/opal-api/index.rst
index b2fe942c7..96ce62a28 100644
--- a/doc/opal-api/index.rst
+++ b/doc/opal-api/index.rst
@@ -384,6 +384,12 @@ The OPAL API is the interface between an Operating System and OPAL.
+---------------------------------------------+--------------+------------------------+----------+-----------------+
| :ref:`OPAL_NPU_MEM_RELEASE` | 172 | Future, likely 6.4 | | |
+---------------------------------------------+--------------+------------------------+----------+-----------------+
+| :ref:`OPAL_MPIPL_UPDATE` | 173 | Future, likely 6.4 | POWER9 | |
++---------------------------------------------+--------------+------------------------+----------+-----------------+
+| :ref:`OPAL_MPIPL_REGISTER_TAG` | 174 | Future, likely 6.4 | POWER9 | |
++---------------------------------------------+--------------+------------------------+----------+-----------------+
+| :ref:`OPAL_MPIPL_QUERY_TAG` | 175 | Future, likely 6.4 | POWER9 | |
++---------------------------------------------+--------------+------------------------+----------+-----------------+
.. toctree::
:maxdepth: 1
diff --git a/doc/opal-api/opal-cec-reboot-6-116.rst b/doc/opal-api/opal-cec-reboot-6-116.rst
index 9a5c79446..431098f3b 100644
--- a/doc/opal-api/opal-cec-reboot-6-116.rst
+++ b/doc/opal-api/opal-cec-reboot-6-116.rst
@@ -1,3 +1,5 @@
+.. _opal-api-cec-reboot:
+
OPAL_CEC_REBOOT and OPAL_CEC_REBOOT2
====================================
diff --git a/doc/opal-api/opal-mpipl-173-174.rst b/doc/opal-api/opal-mpipl-173-174.rst
new file mode 100644
index 000000000..fa275693f
--- /dev/null
+++ b/doc/opal-api/opal-mpipl-173-174.rst
@@ -0,0 +1,156 @@
+.. _opal-api-mpipl:
+
+OPAL MPIPL APIs
+===============
+
+.. code-block:: c
+
+ #define OPAL_MPIPL_UPDATE 173
+ #define OPAL_MPIPL_REGISTER_TAG 174
+ #define OPAL_MPIPL_QUERY_TAG 175
+
+These calls are used for MPIPL (Memory Preserving Initial Program Load).
+
+It is an OPTIONAL part of the OPAL spec.
+
+If a platform supports MPIPL, then we will have "/ibm,opal/dump" node in
+device tree (see :ref:`device-tree/ibm,opal/dump`).
+
+.. _OPAL_MPIPL_UPDATE:
+
+OPAL_MPIPL_UPDATE
+==================
+Linux kernel will use this call to register/unregister MPIPL.
+
+.. code-block:: c
+
+ #define OPAL_MPIPL_UPDATE 173
+
+ int64_t opal_mpipl_update(enum mpipl_ops ops, u64 src, u64 dest, u64 size)
+
+ /* MPIPL update operations */
+ enum mpipl_ops {
+ OPAL_MPIPL_ADD_RANGE = 0,
+ OPAL_MPIPL_REMOVE_RANGE = 1,
+ OPAL_MPIPL_REMOVE_ALL = 2,
+ OPAL_MPIPL_FREE_PRESERVED_MEMORY= 3,
+ };
+
+ops :
+-----
+ OPAL_MPIPL_ADD_RANGE
+ Add new entry to MPIPL table. Kernel will send src, dest and size.
+ During MPIPL content from source address is moved to destination address.
+ src = Source start address
+ dest = Destination start address
+ size = size
+
+ OPAL_MPIPL_REMOVE_RANGE
+ Remove kernel requested entry from MPIPL table.
+ src = Source start address
+ dest = Destination start address
+ size = ignore
+
+ OPAL_MPIPL_REMOVE_ALL
+ Remove all kernel passed entry from MPIPL table.
+ src = ignore
+ dest = ignore
+ size = ignore
+
+ OPAL_MPIPL_FREE_PRESERVED_MEMORY
+ Post MPIPL, kernel will indicate OPAL that it has processed dump and
+ it can clear/release metadata area.
+ src = ignore
+ dest = ignore
+ size = ignore
+
+Return Values
+-------------
+
+``OPAL_SUCCESS``
+ Operation success
+
+``OPAL_PARAMETER``
+ Invalid parameter
+
+``OPAL_RESOURCE``
+ Ran out of space in MDST/MDDT table to add new entry
+
+``OPAL_HARDWARE``
+ Platform does not support fadump
+
+
+.. _OPAL_MPIPL_REGISTER_TAG:
+
+OPAL_MPIPL_REGISTER_TAG
+=======================
+Kernel will use this API to register tags during MPIPL registration.
+It expects OPAL to preserve these tags across MPIPL. Post MPIPL Linux
+kernel will use `opal_mpipl_query_tag` call to retrieve these tags.
+
+.. code-block:: c
+ opal_mpipl_register_tag(enum opal_mpipl_tags tag, uint64_t tag_val)
+
+ tag:
+ OPAL_MPIPL_TAG_KERNEL
+ During first boot, kernel will setup its metadata area and asks
+ OPAL to preserve metadata area pointer across MPIPL. Post MPIPL
+ kernel requests OPAL to provide metadata pointer and it will use
+ that pointer to retrieve metadata and create dump.
+
+ OPAL_MPIPL_TAG_BOOT_MEM
+ During MPIPL registration kernel will specify how much memory
+ firmware can use for Post MPIPL load. Post MPIPL petitboot kernel
+ will query for this tag to get boot memory size.
+
+Return Values
+-------------
+``OPAL_SUCCESS``
+ Operation success
+
+``OPAL_PARAMETER``
+ Invalid parameter
+
+.. _OPAL_MPIPL_QUERY_TAG:
+
+OPAL_MPIPL_QUERY_TAG
+====================
+Post MPIPL linux kernel will call this API to get metadata tag. And use this
+tag to retrieve metadata information and generate dump.
+
+.. code-block:: c
+
+ #define OPAL_MPIPL_QUERY_TAG 175
+
+ uint64_t opal_mpipl_query_tag(enum opal_mpipl_tags tag, uint64_t *tag_val)
+
+ enum opal_mpipl_tags {
+ OPAL_MPIPL_TAG_CPU = 0,
+ OPAL_MPIPL_TAG_OPAL = 1,
+ OPAL_MPIPL_TAG_KERNEL = 2,
+ OPAL_MPIPL_TAG_BOOT_MEM = 3,
+ };
+
+ tag :
+ OPAL_MPIPL_TAG_CPU
+ Pointer to CPU register data content metadata area
+ OPAL_MPIPL_TAG_OPAL
+ Pointer to OPAL metadata area
+ OPAL_MPIPL_TAG_KERNEL
+ During first boot, kernel will setup its metadata area and asks
+ OPAL to preserve metadata area pointer across MPIPL. Post MPIPL
+ kernel calls this API to get metadata pointer and it will use
+ that pointer to retrieve metadata and create dump.
+ OPAL_MPIPL_TAG_BOOT_MEM
+ During MPIPL registration kernel will specify how much memory
+ firmware can use for Post MPIPL load. Post MPIPL petitboot kernel
+ will query for this tag to get boot memory size.
+
+Return Values
+-------------
+
+``OPAL_SUCCESS``
+ Operation success
+
+``OPAL_PARAMETER``
+ Invalid parameter
--
2.14.3
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