[RFC PATCH 25/36] arm_mpam: Register and enable IRQs

[James Morse]

Hi Shaopeng,

On 16/07/2025 08:31, Shaopeng Tan (Fujitsu) wrote:
>> Register and enable error IRQs. All the MPAM error interrupts indicate a
>> software bug, e.g. out of range partid. If the error interrupt is ever signalled,
>> attempt to disable MPAM.
>>
>> Only the irq handler accesses the ESR register, so no locking is needed.
>> The work to disable MPAM after an error needs to happen at process context,
>> use a threaded interrupt.
>>
>> There is no support for percpu threaded interrupts, for now schedule the work
>> to be done from the irq handler.
>>
>> Enabling the IRQs in the MSC may involve cross calling to a CPU that can
>> access the MSC.

>> diff --git a/drivers/platform/arm64/mpam/mpam_devices.c
>> b/drivers/platform/arm64/mpam/mpam_devices.c
>> index 145535cd4732..af19cc25d16e 100644
>> --- a/drivers/platform/arm64/mpam/mpam_devices.c
>> +++ b/drivers/platform/arm64/mpam/mpam_devices.c

>> +static irqreturn_t __mpam_irq_handler(int irq, struct mpam_msc *msc) {
>> +	u64 reg;
>> +	u16 partid;
>> +	u8 errcode, pmg, ris;
>> +
>> +	if (WARN_ON_ONCE(!msc) ||
>> +	    WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(),
>> +					   &msc->accessibility)))
>> +		return IRQ_NONE;
>> +
>> +	reg = mpam_msc_read_esr(msc);
>> +
>> +	errcode = FIELD_GET(MPAMF_ESR_ERRCODE, reg);
>> +	if (!errcode)
>> +		return IRQ_NONE;
>> +
>> +	/* Clear level triggered irq */
>> +	mpam_msc_zero_esr(msc);
>> +
>> +	partid = FIELD_GET(MPAMF_ESR_PARTID_OR_MON, reg);
>> +	pmg = FIELD_GET(MPAMF_ESR_PMG, reg);
>> +	ris = FIELD_GET(MPAMF_ESR_PMG, reg);
> MPAMF_ESR_RIS?

Yup, thanks for catching that!


James