Re: [Qemu-devel] [PATCH v17 06/10] docs: APEI GHES generation and CPER record description

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 14 May 2019 04:18:19 -0700
Dongjiu Geng <gengdongjiu@huawei.com> wrote:

> Add APEI/GHES detailed design document
> 
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
> ---
>  docs/specs/acpi_hest_ghes.txt | 97 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 97 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 0000000..fbfc787
> --- /dev/null
> +++ b/docs/specs/acpi_hest_ghes.txt
> @@ -0,0 +1,97 @@
> +APEI tables generating and CPER record
> +=============================
> +
> +Copyright (C) 2017 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 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

s/one/a/
in both cases

> +    table, all of which are pre-allocated.

drop /, all of which are pre-allocated./

> +
> +(3) The address registers table contains N Error Block 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
> +    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.
where 'N' is specified?

> +
> +(4) QEMU generates the ACPI linker/loader script for the firmware
> +
> +(4a) The HEST table is part of "etc/acpi/tables", the firmware already
> +    allocates the memory for it, 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.
may be merge both points, like:

    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 the downloaded "etc/hardware_errors"
> +    blob.

s/the downloaded//
the same applies to to other similar occurrences below

> +
> +(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 the downloaded "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 the downloaded "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". 

> Then
> +    Qemu will know the Error Status Data Block for every error source. Each of
> +    Error Status Data Block has fixed size which is 4096(0x1000).

this probably is not necessary.

> +
> +(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.