ACK/Cmnt: [SRU][j:linux-gcp-6.8][PATCH v2 0/1] Enable IOMMU Passthrough by default

[Agathe Porte]

2024-11-05 17:29 CET, Ian Whitfield:
> [Impact]
> 
> C3 bare metal instances run into a problem on 6.8 kernels due to Intel
> IOMMU being enabled by default. After performing enough disk-intensive
> work on the instance, the system becomes unusable and reports I/O
> errors at the command line until rebooted, losing data in the process.
> The root issue is being worked on long-term, but in the meantime we
> will apply a workaround to the issue for affected customers. This fix
> has a negative impact on security, so it is limited to Jammy kernels
> for which this issue is a regression. Noble kernels have always had
> this problem and therefore will be waiting for the long-term fix.
> 
> [Fix]
> 
> Change the kernel config to use IOMMU passthrough by default.
> 
> [Test Plan]
> 
> Perform up to 50 kernel builds on the instance in sequence. Failures on
> affected instances are usually detected after only 1 or 2.
> 
> [Regression potential]
> 
> Regression potential is especially low for Jammy as we are essentially
> reverting a breaking change.
> 
> v2: Fixed subject line (was j:linux-gcp)
> 
> Ian Whitfield (1):
>   UBUNTU: gcp: Enable IOMMU Passthrough by default
> 
>  debian.gcp-6.8/config/annotations | 9 +++++++++
>  1 file changed, 9 insertions(+)

Bugling was missing in cover letter.
Other than that, LGTM.

Acked-by: Agathe Porte <agathe.porte at canonical.com>