[PATCH v18 2/6] docs: APEI GHES generation and CPER record description

[Xiang Zheng <zhengxiang9@huawei.com>]

From: Dongjiu Geng <gengdongjiu@huawei.com>

Add APEI/GHES detailed design document

Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
---
 docs/specs/acpi_hest_ghes.txt | 88 +++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 docs/specs/acpi_hest_ghes.txt

diff --git a/docs/specs/acpi_hest_ghes.txt b/docs/specs/acpi_hest_ghes.txt
new file mode 100644
index 0000000000..690d4b2bd0
--- /dev/null
+++ b/docs/specs/acpi_hest_ghes.txt
@@ -0,0 +1,88 @@
+APEI tables generating and CPER record
+=============================
+
+Copyright (C) 2019 Huawei Corporation.
+
+Design Details:
+-------------------
+
+       etc/acpi/tables                                 etc/hardware_errors
+    ====================                      ==========================================
++ +--------------------------+            +-----------------------+
+| | HEST                     |            |    address            |            +--------------+
+| +--------------------------+            |    registers          |            | Error Status |
+| | GHES1                    |            | +---------------------+            | Data Block 1 |
+| +--------------------------+ +--------->| |error_block_address1 |----------->| +------------+
+| | .................        | |          | +---------------------+            | |  CPER      |
+| | error_status_address-----+-+ +------->| |error_block_address2 |--------+   | |  CPER      |
+| | .................        |   |        | +---------------------+        |   | |  ....      |
+| | read_ack_register--------+-+ |        | |    ..............   |        |   | |  CPER      |
+| | read_ack_preserve        | | |        +-----------------------+        |   | +------------+
+| | read_ack_write           | | | +----->| |error_block_addressN |------+ |   | Error Status |
++ +--------------------------+ | | |      | +---------------------+      | |   | Data Block 2 |
+| | GHES2                    | +-+-+----->| |read_ack_register1   |      | +-->| +------------+
++ +--------------------------+   | |      | +---------------------+      |     | |  CPER      |
+| | .................        |   | | +--->| |read_ack_register2   |      |     | |  CPER      |
+| | error_status_address-----+---+ | |    | +---------------------+      |     | |  ....      |
+| | .................        |     | |    | |  .............      |      |     | |  CPER      |
+| | read_ack_register--------+-----+-+    | +---------------------+      |     +-+------------+
+| | read_ack_preserve        |     |   +->| |read_ack_registerN   |      |     | |..........  |
+| | read_ack_write           |     |   |  | +---------------------+      |     | +------------+
++ +--------------------------|     |   |                                 |     | Error Status |
+| | ...............          |     |   |                                 |     | Data Block N |
++ +--------------------------+     |   |                                 +---->| +------------+
+| | GHESN                    |     |   |                                       | |  CPER      |
++ +--------------------------+     |   |                                       | |  CPER      |
+| | .................        |     |   |                                       | |  ....      |
+| | error_status_address-----+-----+   |                                       | |  CPER      |
+| | .................        |         |                                       +-+------------+
+| | read_ack_register--------+---------+
+| | read_ack_preserve        |
+| | read_ack_write           |
++ +--------------------------+
+
+(1) QEMU generates the ACPI HEST table. This table goes in the current
+    "etc/acpi/tables" fw_cfg blob. Each error source has different
+    notification types.
+
+(2) A new fw_cfg blob called "etc/hardware_errors" is introduced. QEMU
+    also need to populate this blob. The "etc/hardwre_errors" fw_cfg blob
+    contains an address registers table and an Error Status Data Block table.
+
+(3) The address registers table contains N Error Block Address entries
+    and N Read Ack Register entries, the size for each entry is 8-byte.
+    The Error Status Data Block table contains N Error Status Data Block
+    entries, the size for each entry is 4096(0x1000) bytes. The total size
+    for "etc/hardware_errors" fw_cfg blob is (N * 8 * 2 + N * 4096) bytes.
+    N is the kinds of hardware error sources.
+
+(4) QEMU generates the ACPI linker/loader script for the firmware, the
+    firmware pre-allocates memory for "etc/acpi/tables", "etc/hardware_errors"
+    and copies blobs content there.
+
+(5) QEMU generates N ADD_POINTER commands, which patch address in the
+    "error_status_address" fields of the HEST table with a pointer to the
+    corresponding "address registers" in "etc/hardware_errors" blob.
+
+(6) QEMU generates N ADD_POINTER commands, which patch address in the
+    "read_ack_register" fields of the HEST table with a pointer to the
+    corresponding "address registers" in "etc/hardware_errors" blob.
+
+(7) QEMU generates N ADD_POINTER commands for the firmware, which patch
+    address in the " error_block_address" fields with a pointer to the
+    respective "Error Status Data Block" in "etc/hardware_errors" blob.
+
+(8) QEMU defines a third and write-only fw_cfg blob which is called
+    "etc/hardware_errors_addr". Through that blob, the firmware can send back
+    the guest-side allocation addresses to QEMU. The "etc/hardware_errors_addr"
+    blob contains a 8-byte entry. QEMU generates a single WRITE_POINTER commands
+    for the firmware, the firmware will write back the start address of
+    "etc/hardware_errors" blob to fw_cfg file "etc/hardware_errors_addr".
+
+(9) When QEMU gets SIGBUS from the kernel, QEMU formats the CPER right into
+    guest memory, and then injects whatever interrupt (or assert whatever GPIO
+    line) as a notification which is necessary for notifying the guest.
+
+(10) This notification (in virtual hardware) will be handled by guest kernel,
+    guest APEI driver will read the CPER which is recorded by QEMU and do the
+    recovery.
-- 
2.19.1