Re: [PATCH 2/2] tools/virtio: add a vhost dirty log test

[sashiko-bot@kernel.org]

> From: Khan Zhao <zhaoguohan@kylinos.cn>
> 
> Add vhost_log_test, which exercises used-ring dirty logging through the
> existing vhost_test module. It sets a log base with VHOST_SET_LOG_BASE,
> enables VHOST_VRING_F_LOG on the ring, submits descriptors and checks
> the resulting bitmap from userspace. No new kernel interface is needed.
> 
> The test covers:
> 
>  - every bit in a byte, repeated sets, and neighbouring bytes being left
>    untouched, including the last byte of a page followed by a PROT_NONE
>    guard page
>  - a log page that has not been faulted in yet, read-only, PROT_NONE
>    and unmapped log pages, and logging after access is restored
>  - private (COW) and shared file mappings, checking that the bit reaches
> [ ... ]
> A --bench mode reports ns per descriptor with logging disabled and
> enabled. vhost_log_test.rst describes how to build and run the test.
> 
> Assisted-by: Codex:gpt-6.1-sol
> Signed-off-by: Khan Zhao <zhaoguohan@kylinos.cn>

Sashiko has reviewed this patch and found no issues.

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