111 lines
6.7 KiB
ReStructuredText
111 lines
6.7 KiB
ReStructuredText
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APEI tables generating and CPER record
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======================================
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..
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Copyright (c) 2020 HUAWEI TECHNOLOGIES CO., LTD.
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This work is licensed under the terms of the GNU GPL, version 2 or later.
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See the COPYING file in the top-level directory.
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Design Details
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--------------
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::
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etc/acpi/tables etc/hardware_errors
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==================== ===============================
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+ +--------------------------+ +----------------------------+
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| | HEST | +--------->| error_block_address1 |------+
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| +--------------------------+ | +----------------------------+ |
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| | GHES1 | | +------->| error_block_address2 |------+-+
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| +--------------------------+ | | +----------------------------+ | |
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| | ................. | | | | .............. | | |
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| | error_status_address-----+-+ | -----------------------------+ | |
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| | ................. | | +--->| error_block_addressN |------+-+---+
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| | read_ack_register--------+-+ | | +----------------------------+ | | |
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| | read_ack_preserve | +-+---+--->| read_ack_register1 | | | |
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| | read_ack_write | | | +----------------------------+ | | |
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+ +--------------------------+ | +-+--->| read_ack_register2 | | | |
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| | GHES2 | | | | +----------------------------+ | | |
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+ +--------------------------+ | | | | ............. | | | |
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| | ................. | | | | +----------------------------+ | | |
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| | error_status_address-----+---+ | | +->| read_ack_registerN | | | |
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| | ................. | | | | +----------------------------+ | | |
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| | read_ack_register--------+-----+ | | |Generic Error Status Block 1|<-----+ | |
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| | read_ack_preserve | | | |-+------------------------+-+ | |
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| | read_ack_write | | | | | CPER | | | |
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+ +--------------------------| | | | | CPER | | | |
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| | ............... | | | | | .... | | | |
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+ +--------------------------+ | | | | CPER | | | |
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| | GHESN | | | |-+------------------------+-| | |
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+ +--------------------------+ | | |Generic Error Status Block 2|<-------+ |
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| | ................. | | | |-+------------------------+-+ |
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| | error_status_address-----+-------+ | | | CPER | | |
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| | ................. | | | | CPER | | |
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| | read_ack_register--------+---------+ | | .... | | |
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| | read_ack_preserve | | | CPER | | |
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| | read_ack_write | +-+------------------------+-+ |
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+ +--------------------------+ | .......... | |
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|----------------------------+ |
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|Generic Error Status Block N |<----------+
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|-+-------------------------+-+
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| | CPER | |
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| | CPER | |
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| | .... | |
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| | CPER | |
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+-+-------------------------+-+
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(1) QEMU generates the ACPI HEST table. This table goes in the current
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"etc/acpi/tables" fw_cfg blob. Each error source has different
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notification types.
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(2) A new fw_cfg blob called "etc/hardware_errors" is introduced. QEMU
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also needs to populate this blob. The "etc/hardware_errors" fw_cfg blob
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contains an address registers table and an Error Status Data Block table.
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(3) The address registers table contains N Error Block Address entries
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and N Read Ack Register entries. The size for each entry is 8-byte.
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The Error Status Data Block table contains N Error Status Data Block
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entries. The size for each entry is 4096(0x1000) bytes. The total size
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for the "etc/hardware_errors" fw_cfg blob is (N * 8 * 2 + N * 4096) bytes.
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N is the number of the kinds of hardware error sources.
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(4) QEMU generates the ACPI linker/loader script for the firmware. The
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firmware pre-allocates memory for "etc/acpi/tables", "etc/hardware_errors"
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and copies blob contents there.
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(5) QEMU generates N ADD_POINTER commands, which patch addresses in the
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"error_status_address" fields of the HEST table with a pointer to the
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corresponding "address registers" in the "etc/hardware_errors" blob.
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(6) QEMU generates N ADD_POINTER commands, which patch addresses in the
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"read_ack_register" fields of the HEST table with a pointer to the
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corresponding "read_ack_register" within the "etc/hardware_errors" blob.
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(7) QEMU generates N ADD_POINTER commands for the firmware, which patch
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addresses in the "error_block_address" fields with a pointer to the
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respective "Error Status Data Block" in the "etc/hardware_errors" blob.
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(8) QEMU defines a third and write-only fw_cfg blob which is called
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"etc/hardware_errors_addr". Through that blob, the firmware can send back
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the guest-side allocation addresses to QEMU. The "etc/hardware_errors_addr"
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blob contains a 8-byte entry. QEMU generates a single WRITE_POINTER command
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for the firmware. The firmware will write back the start address of
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"etc/hardware_errors" blob to the fw_cfg file "etc/hardware_errors_addr".
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(9) When QEMU gets a SIGBUS from the kernel, QEMU writes CPER into corresponding
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"Error Status Data Block", guest memory, and then injects platform specific
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interrupt (in case of arm/virt machine it's Synchronous External Abort) as a
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notification which is necessary for notifying the guest.
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(10) This notification (in virtual hardware) will be handled by the guest
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kernel, on receiving notification, guest APEI driver could read the CPER error
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and take appropriate action.
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(11) kvm_arch_on_sigbus_vcpu() uses source_id as index in "etc/hardware_errors" to
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find out "Error Status Data Block" entry corresponding to error source. So supported
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source_id values should be assigned here and not be changed afterwards to make sure
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that guest will write error into expected "Error Status Data Block" even if guest was
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migrated to a newer QEMU.
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