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+Generating APEI tables and record CPER
+=============================
+
+Copyright (C) 2017 HuaWei Corporation.
+
+Design Details:
+-------------------
+
+ etc/acpi/tables etc/hardware_errors
+ ==================== ==========================================
++ +--------------------------+ +------------------+
+| | HEST | | address | +--------------+
+| +--------------------------+ | registers | | Error Status |
+| | GHES1 | | +----------------+ | Data Block 1 |
+| +--------------------------+ +--------->| |status_address1 |------------->| +------------+
+| | ................. | | | +----------------+ | | CPER |
+| | error_status_address-----+-+ +------->| |status_address2 |----------+ | | CPER |
+| | ................. | | | +----------------+ | | | .... |
+| | read_ack_register--------+-+ | | ............. | | | | CPER |
+| | read_ack_preserve | | | +------------------+ | | +------------+
+| | read_ack_write | | | +----->| |status_addressN |--------+ | | Error Status |
++ +--------------------------+ | | | | +----------------+ | | | Data Block 2 |
+| | GHES2 | +-+-+----->| | ack_value1 | | +-->| +------------+
++ +--------------------------+ | | | +----------------+ | | | CPER |
+| | ................. | | | +--->| | ack_value2 | | | | CPER |
+| | error_status_address-----+---+ | | | +----------------+ | | | .... |
+| | ................. | | | | | ............. | | | | CPER |
+| | read_ack_register--------+-----+-+ | +----------------+ | +-+------------+
+| | read_ack_preserve | | +->| | ack_valueN | | | |.......... |
+| | 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 type.
+
+(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
+ one address registers table and one Error Status Data Block table, all
+ of which are pre-allocated.
+
+(3) The address registers table contains N Error Status Address entries
+ and N Read Ack Address entries, the size for each entry is 8-byte. The
+ Error Status Data Block table contains N Error Status Data Block entry,
+ the size for each entry is 0x1000(4096) bytes. The total size for
+ "etc/hardware_errors" fw_cfg blob is (N * 8 * 2 + N * 4096) bytes
+
+(4) QEMU generates the ACPI linker/loader script for the firmware
+
+(4a) The HEST table is part of "etc/acpi/tables", which the firmware
+ already allocates memory for it and downloads, because QEMU already
+ generates an ALLOCATE linker/loader command for it.
+
+(4b) QEMU creates another ALLOCATE command for the "etc/hardware_errors"
+ blob. The firmware allocates memory for this blob,
+ and downloads it.
+
+(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 the downloaded "etc/hardware_errors" blob.
+
+(6) QEMU generates N ADD_POINTER commands for the firmware, pointing the
+ address registers (located in guest memory, in the downloaded
+ "etc/hardware_errors" blob) to the respective Error Status Data Blocks.
+
+(7) QEMU Defines a third, write-only fw_cfg blob, 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 the start
+ address of Error Status Data Block0 back to fw_cfg file "etc/hardware_errors_addr".
+ Then Qemu will know the start address of Error Status Data Block0. For error source K
+ (0 <= K < 2), its address offset is K * 0x1000, because each of Error Status Data Block
+ has fixed size which is 0x1000. Using this way, QEMU will know the address of each
+ Error Status Data Block.
+
+(8) When QEMU gets SIGBUS from the kernel, QEMU format the CPER right into guest
+ memory, and then inject whatever interrupt (or assert whatever GPIO line) which is
+ necessary for notifying the guest.
+
+(9) This notification (in virtual hardware) can either be handled by the
+ guest kernel stand-alone, or else the guest kernel can invoke an ACPI
+ event handler method with it. The ACPI event handler method could
+ invoke the specific guest kernel driver for error handling via a
+ Notify() operation.
+
+For the above design, it would leave the firmware alone after OS boot and firmware no need
+to care about HEST, GHES, CPER.
Add APEI/GHES description document Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> --- Address Igor's comments to add a doc --- docs/specs/acpi_hest_ghes.txt | 98 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 docs/specs/acpi_hest_ghes.txt