Re: [PATCH 1/1] acpi: Implement ACPI ERST support for guests

[Eric Devolder]

Paolo,

Thanks for the feedback. I've posted v2 with changes based on Igor's feedback.

I've also included a qtest per your feedback.

Eric

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From: Paolo Bonzini <pbonzini@redhat.com>
Sent: Tuesday, November 3, 2020 3:16 PM
To: Eric DeVolder <eric.devolder@oracle.com>; qemu-devel@nongnu.org <qemu-devel@nongnu.org>
Cc: mst@redhat.com <mst@redhat.com>; imammedo@redhat.com <imammedo@redhat.com>; marcel.apfelbaum@gmail.com <marcel.apfelbaum@gmail.com>; rth@twiddle.net <rth@twiddle.net>; ehabkost@redhat.com <ehabkost@redhat.com>; konrad.wilk@oracle.com <konrad.wilk@oracle.com>; boris.ostrovsky@oracle.com <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH 1/1] acpi: Implement ACPI ERST support for guests

 

On 26/10/20 21:19, Eric DeVolder wrote:
> This changeset introduces support for the ACPI Error Record
> Serialization Table, ERST.
>
> ERST is defined in [1], and the error records are defined
> according to [2].
>
> This changeset generates the ACPI ERST table, which OSPM
> follows to program the associated ERST device. The ERST
> device occupies 8KiB of address space, with the first 8 bytes
> containing registers, and the remainder being an exchange
> buffer for reading/writing error records.
>
> The ERST device contains two registers, ACTION and VALUE
> registers, following closely the ERST operations.
>
> The ERST device only examines the record for the signature 'CPER',
> its record identifier, and bounds-checks the length against the size
> of the the CPER record header; otherwise all other record fields
> and payload are ignored.
>
> There are two options for this device:
>   -global acpi-erst.size=X
>   -global acpi-erst.filename=Y
> The size X, if not specified, defaults to 64KiB, and must be within
> 64KiB and 1MiB.
> The filename Y, if not specified, defaults to "acpi-erst.backing".
> The ERST backing storage is not mapped into the guest address space,
> just the 8KiB programming area is mapped into the guest.
>
> This has been utilized as a backend for the Linux pstore feature.
>
> [1] ACPI 6.3 Specification, 18.3 Error Serialization
>      https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
>
> [2] UEFI 2.8 Specification, Appendix N Common Platform Error Record
>      https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf

In addition to what Igor said, this really needs a test for the device
(using qtest).  It doesn't have to be super fine-grained, but at least a
smoke test that the action and value registers do what they mean for a
sample error recording operation.

Paolo