Re: [PATCH v3 4/9] perf/cxl: Split the MSI vector out of info->irq

[Dave Jiang <dave.jiang@intel.com>]

On 8/3/26 5:04 AM, Robin Murphy wrote:
> On 01/08/2026 12:28 am, Dave Jiang wrote:
>> info->irq means two different things depending on how far probe has got.
>> cxl_pmu_parse_caps() sets it to the MSI/MSI-X message number from the CPMU
>> Capability register. cxl_pmu_probe() passes that to pci_irq_vector() and
>> then overwrites it with the Linux virq, which is what the hotplug callbacks
>> hand to irq_set_affinity().
>>
>> Give the message number its own field. No functional change.
> 
> Thanks, this makes it much less confusing;
> 
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> 
> If the fix itself was just the comparison operator then I'd suggest folding it in so as to avoid extra backporting dependencies/conflicts, but it sounds like we might have a corner case where 0 may still mean "no IRQ", so maybe sort that first then put this refactoring on top?

Will do. I'll flip the order.

DJ

> 
> Cheers,
> Robin.
> 
>> Assisted-by: Claude:claude-opus-4-8
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>> v3:
>> - New patch
>> ---
>>   drivers/perf/cxl_pmu.c | 9 +++++----
>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
>> index 3511d049aea4..56e6ae7bebf7 100644
>> --- a/drivers/perf/cxl_pmu.c
>> +++ b/drivers/perf/cxl_pmu.c
>> @@ -106,6 +106,7 @@ struct cxl_pmu_info {
>>       int on_cpu;
>>       struct hlist_node node;
>>       bool filter_hdm;
>> +    int msi_vec;
>>       int irq;
>>   };
>>   @@ -143,9 +144,9 @@ static int cxl_pmu_parse_caps(struct device *dev, struct cxl_pmu_info *info)
>>         info->filter_hdm = FIELD_GET(CXL_PMU_CAP_FILTERS_SUP_MSK, val) & CXL_PMU_FILTER_HDM;
>>       if (FIELD_GET(CXL_PMU_CAP_INT, val))
>> -        info->irq = FIELD_GET(CXL_PMU_CAP_MSI_N_MSK, val);
>> +        info->msi_vec = FIELD_GET(CXL_PMU_CAP_MSI_N_MSK, val);
>>       else
>> -        info->irq = -1;
>> +        info->msi_vec = -1;
>>         /* First handle fixed function counters; note if configurable counters found */
>>       for (i = 0; i < info->num_counters; i++) {
>> @@ -874,10 +875,10 @@ static int cxl_pmu_probe(struct device *dev)
>>           .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
>>       };
>>   -    if (info->irq <= 0)
>> +    if (info->msi_vec <= 0)
>>           return -EINVAL;
>>   -    rc = pci_irq_vector(pdev, info->irq);
>> +    rc = pci_irq_vector(pdev, info->msi_vec);
>>       if (rc < 0)
>>           return rc;
>>       irq = rc;
>