Re: [PATCH v6 7/7] drm/xe/tests: Add KUnit tests for VF provisioning error handling

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The GGTT initialization path skips alignment validation and performs partial state updates before validation completes, which the new KUnit tests fail to detect.
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--- Patch [7]: [PATCH v6 7/7] drm/xe/tests: Add KUnit tests for VF provisioning error handling ---
commit 5074ef2c8cf15b0dd4c9cdf94819ab386e4100b7
Author: Satyanarayana K V P <[email protected]>

drm/xe/tests: Add KUnit tests for VF provisioning error handling

This commit adds KUnit test cases for VF provisioning error handling. It
uses the xe_guc_mmio_send_recv() stub to inject bad KLV responses and
verifies that the VF can handle invalid configuration data.

> diff --git a/drivers/gpu/drm/xe/tests/xe_gt_sriov_vf_kunit.c b/drivers/gpu/drm/xe/tests/xe_gt_sriov_vf_kunit.c
> new file mode 100644
> index 0000000000000..8cb7f3cebb311
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/tests/xe_gt_sriov_vf_kunit.c
[ ... ]
> +struct config_ggtt {
> +	u64 start_orig;
> +	u64 start_query;
> +	u64 size_orig;
> +	u64 size_query;
> +	int expected_ret;
> +	int ret;
> +	int flags;
> +	const char *name;
> +} vf_ggtt_testcase[] = {
[ ... ]
> +	{
> +		.start_orig = TEST_GGTT_START,		.start_query = TEST_GGTT_START,
> +		.size_orig = TEST_GGTT_SIZE - SZ_2K,	.size_query = TEST_GGTT_SIZE - SZ_2K,
> +		.expected_ret = -EINVAL,		.flags = 0,
> +		.name = "unaligned_size_4K",
> +
> +	},

[Severity: High]
This is a pre-existing issue, but the new KUnit tests unintentionally mask
a bug in the early return path of vf_get_ggtt_info().

By setting size_orig to a non-zero value (TEST_GGTT_SIZE - SZ_2K) in this
unaligned test case, the test avoids the initial provisioning path. If
size_orig was set to 0 (which reflects the actual initial provisioning state),
the test would fail because vf_get_ggtt_info() incorrectly returns 0 instead
of -EINVAL.

Looking at vf_get_ggtt_info() in drivers/gpu/drm/xe/xe_gt_sriov_vf.c:

	xe_tile_sriov_vf_ggtt_base_store(tile, start);
	ggtt_size = xe_tile_sriov_vf_ggtt(tile);
	if (!ggtt_size) {
		/* ... */
		xe_tile_sriov_vf_ggtt_store(tile, size);
		return 0;
	}

During initial provisioning (when ggtt_size is 0), unvalidated start and size
values are stored and the function returns early, completely bypassing the
IS_ALIGNED validation checks that occur later in the function.

Should the alignment checks in vf_get_ggtt_info() be moved before this early
return, and should these KUnit tests be updated to include scenarios where
size_orig is 0 to verify the initial provisioning path?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=7