Re: [PATCH v22 2/9] docs: APEI GHES generation and CPER record description

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 8 Jan 2020 19:32:16 +0800
Dongjiu Geng <gengdongjiu@huawei.com> wrote:

> Add APEI/GHES detailed design document
> 
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
> Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  docs/specs/acpi_hest_ghes.rst | 110 ++++++++++++++++++++++++++++++++++++++++++
>  docs/specs/index.rst          |   1 +
>  2 files changed, 111 insertions(+)
>  create mode 100644 docs/specs/acpi_hest_ghes.rst
> 
> diff --git a/docs/specs/acpi_hest_ghes.rst b/docs/specs/acpi_hest_ghes.rst
> new file mode 100644
> index 0000000..7a1aa90
> --- /dev/null
> +++ b/docs/specs/acpi_hest_ghes.rst
> @@ -0,0 +1,110 @@
> +APEI tables generating and CPER record
> +======================================
> +
> +..
> +   Copyright (c) 2019 HUAWEI TECHNOLOGIES CO., LTD.
> +
> +   This work is licensed under the terms of the GNU GPL, version 2 or later.
> +   See the COPYING file in the top-level directory.
> +
> +Design Details
> +--------------
> +
> +::
> +
> +         etc/acpi/tables                           etc/hardware_errors
> +      ====================                   ===============================
> +  + +--------------------------+            +----------------------------+
> +  | | HEST                     | +--------->|    error_block_address1    |------+
> +  | +--------------------------+ |          +----------------------------+      |
> +  | | GHES1                    | | +------->|    error_block_address2    |------+-+
> +  | +--------------------------+ | |        +----------------------------+      | |
> +  | | .................        | | |        |      ..............        |      | |
> +  | | error_status_address-----+-+ |        -----------------------------+      | |
> +  | | .................        |   |   +--->|    error_block_addressN    |------+-+---+
> +  | | read_ack_register--------+-+ |   |    +----------------------------+      | |   |
> +  | | read_ack_preserve        | +-+---+--->|     read_ack_register1     |      | |   |
> +  | | read_ack_write           |   |   |    +----------------------------+      | |   |
> +  + +--------------------------+   | +-+--->|     read_ack_register2     |      | |   |
> +  | | GHES2                    |   | | |    +----------------------------+      | |   |
> +  + +--------------------------+   | | |    |       .............        |      | |   |
> +  | | .................        |   | | |    +----------------------------+      | |   |
> +  | | error_status_address-----+---+ | | +->|     read_ack_registerN     |      | |   |
> +  | | .................        |     | | |  +----------------------------+      | |   |
> +  | | read_ack_register--------+-----+ | |  |Generic Error Status Block 1|<-----+ |   |
> +  | | read_ack_preserve        |       | |  |-+------------------------+-+        |   |
> +  | | read_ack_write           |       | |  | |          CPER          | |        |   |
> +  + +--------------------------|       | |  | |          CPER          | |        |   |
> +  | | ...............          |       | |  | |          ....          | |        |   |
> +  + +--------------------------+       | |  | |          CPER          | |        |   |
> +  | | GHESN                    |       | |  |-+------------------------+-|        |   |
> +  + +--------------------------+       | |  |Generic Error Status Block 2|<-------+   |
> +  | | .................        |       | |  |-+------------------------+-+            |
> +  | | error_status_address-----+-------+ |  | |           CPER         | |            |
> +  | | .................        |         |  | |           CPER         | |            |
> +  | | read_ack_register--------+---------+  | |           ....         | |            |
> +  | | read_ack_preserve        |            | |           CPER         | |            |
> +  | | read_ack_write           |            +-+------------------------+-+            |
> +  + +--------------------------+            |         ..........         |            |
> +                                            |----------------------------+            |
> +                                            |Generic Error Status Block N |<----------+
> +                                            |-+-------------------------+-+
> +                                            | |          CPER           | |
> +                                            | |          CPER           | |
> +                                            | |          ....           | |
> +                                            | |          CPER           | |
> +                                            +-+-------------------------+-+
> +
> +
> +(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 needs to populate this blob. The "etc/hardware_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 the "etc/hardware_errors" fw_cfg blob is (N * 8 * 2 + N * 4096) bytes.
> +    N is the number of 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 blob contents there.
> +
> +(5) QEMU generates N ADD_POINTER commands, which patch addresses in the
> +    "error_status_address" fields of the HEST table with a pointer to the
> +    corresponding "address registers" in the "etc/hardware_errors" blob.
> +
> +(6) QEMU generates N ADD_POINTER commands, which patch addresses in the
> +    "read_ack_register" fields of the HEST table with a pointer to the
> +    corresponding "read_ack_register" within the "etc/hardware_errors" blob.
> +
> +(7) QEMU generates N ADD_POINTER commands for the firmware, which patch
> +    addresses in the "error_block_address" fields with a pointer to the
> +    respective "Error Status Data Block" in the "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 command
> +    for the firmware. The firmware will write back the start address of
> +    "etc/hardware_errors" blob to the fw_cfg file "etc/hardware_errors_addr".
> +
> +(9) When QEMU gets a SIGBUS from the kernel, QEMU writes CPER into corresponding
> +    "Error Status Data Block", guest memory, and then injects platform specific
> +    interrupt (in case of arm/virt machine it's Synchronous External Abort) as a
> +    notification which is necessary for notifying the guest.
> +
> +(10) This notification (in virtual hardware) will be handled by the guest
> +     kernel, on receiving notification, guest APEI driver could read the CPER error
> +     and take appropriate action.
> +
> +(11) kvm_arch_on_sigbus_vcpu() uses source_id as index in "etc/hardware_errors" to
> +     find out "Error Status Data Block" entry corresponding to error source. So supported
> +     source_id values should be assigned here and not be changed afterwards to make sure
> +     that guest will write error into expected "Error Status Data Block" even if guest was
> +     migrated to a newer QEMU.
> diff --git a/docs/specs/index.rst b/docs/specs/index.rst
> index 984ba44..3019b9c 100644
> --- a/docs/specs/index.rst
> +++ b/docs/specs/index.rst
> @@ -13,3 +13,4 @@ Contents:
>     ppc-xive
>     ppc-spapr-xive
>     acpi_hw_reduced_hotplug
> +   acpi_hest_ghes