Re: [PATCH v2 4/9] perf/cxl: Accept an overflow interrupt on MSI message number 0

On Wed, 29 Jul 2026, Dave Jiang wrote:

>cxl_pmu_probe() rejects the PMU with -EINVAL when info->irq <= 0, but
>info->irq holds the MSI/MSI-X message number the device signals overflow
>on (CXL_PMU_CAP_MSI_N_MSK, a 0-based 4-bit field), with -1 meaning "no
>interrupt support". Message number 0 is valid and pci_irq_vector() takes
>a 0-based index, so a compliant device signalling on the first vector is
>wrongly refused and fails to probe.
>
>Reject only the no-interrupt case (info->irq < 0), matching the sibling
>CXL mailbox and event IRQ handling.
>
>Fixes: 5d7107c72796 ("perf: CXL Performance Monitoring Unit driver")
>Reported-by: [email protected]
>Closes: https://sashiko.dev/#/patchset/[email protected]?part=1
>Assisted-by: Claude:claude-opus-4-8
>Signed-off-by: Dave Jiang <[email protected]>

Reviewed-by: Davidlohr Bueso <[email protected]>