Re: [PATCH i-g-t 4/4] tests/intel/xe_fault_injection: Inject errors during xe_guc_ct_send_recv & xe_guc_mmio_send_recv.

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 18.02.2025 14:48, Francois Dugast wrote:
> On Fri, Feb 07, 2025 at 12:59:02PM +0530, Satyanarayana K V P wrote:

>> +
>> +	/* Get the iteration count from environment */
>> +	iter = get_fault_inject_iter();
>> +	iter_start = iter ? : 0;
>> +	iter_end = iter ? iter + 1 : INJECT_ITERATIONS;
>> +	for (int i = iter_start; i < iter_end; i++) {
>> +		fault_params->space = i;
>> +		setup_injection_fault(fault_params);
>> +		inject_fault_probe(fd, pci_slot, function_name);
>> +	}
> 
> This loop is specific to the guc test, it is not present for other tests.
> What is different about this test, why do we need to inject a fault at a
> given iteration?
> 
> In case IGT_FAULT_INJECT_ITERATION is not set, why running
> inject_fault_probe() 100 times instead of just once like with existing
> tests during probe?
> 

Because all xe_init() kind of functions are called just once during
driver probe, so it is sufficient to fail first/all calls to them.

OTOH driver communicates with the GuC multiple times, and the real
failure can happen at different call, hence the need to inject failure
in GuC communication functions, like guc_mmio_send() or guc_ct_send(),
but it can't be just first call or all calls, but we need to be able to
select specific iteration to fail.

Only with that approach we can provide sufficient coverage of the driver
probe related to GuC.

Michal