Re: [PATCH v3 4/8] platform/x86/intel/ifs: Introduce Array Scan test to IFS

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 3/13/23 17:10, Hans de Goede wrote:
> Hi,
> 
> On 3/1/23 02:59, Jithu Joseph wrote:
>> Array BIST is a new type of core test introduced under the Intel Infield
>> Scan (IFS) suite of tests.
>>
>> Emerald Rapids (EMR) is the first CPU to support Array BIST.
>> Array BIST performs tests on some portions of the core logic such as
>> caches and register files. These are different portions of the silicon
>> compared to the parts tested by the first test type
>> i.e Scan at Field (SAF).
>>
>> Make changes in the device driver init flow to register this new test
>> type with the device driver framework. Each test will have its own
>> sysfs directory (intel_ifs_0 , intel_ifs_1) under misc hierarchy to
>> accommodate for the differences in test type and how they are initiated.
>>
>> Upcoming patches will add actual support.
>>
>> Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
>> Reviewed-by: Tony Luck <tony.luck@intel.com>
>> ---
>>  drivers/platform/x86/intel/ifs/ifs.h  |  3 +
>>  drivers/platform/x86/intel/ifs/core.c | 85 +++++++++++++++++++--------
>>  2 files changed, 62 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
>> index ab168ddf28f1..b8b956e29653 100644
>> --- a/drivers/platform/x86/intel/ifs/ifs.h
>> +++ b/drivers/platform/x86/intel/ifs/ifs.h
>> @@ -137,6 +137,9 @@
>>  #define SCAN_TEST_PASS				1
>>  #define SCAN_TEST_FAIL				2
>>  
>> +#define IFS_TYPE_SAF			0
>> +#define IFS_TYPE_ARRAY_BIST		1
>> +
>>  /* MSR_SCAN_HASHES_STATUS bit fields */
>>  union ifs_scan_hashes_status {
>>  	u64	data;
>> diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
>> index 62c44dbae757..2237aaba7078 100644
>> --- a/drivers/platform/x86/intel/ifs/core.c
>> +++ b/drivers/platform/x86/intel/ifs/core.c
>> @@ -16,6 +16,7 @@
>>  
>>  static const struct x86_cpu_id ifs_cpu_ids[] __initconst = {
>>  	X86_MATCH(SAPPHIRERAPIDS_X),
>> +	X86_MATCH(EMERALDRAPIDS_X),
>>  	{}
>>  };
>>  MODULE_DEVICE_TABLE(x86cpu, ifs_cpu_ids);
> 
> Note you can add driver_data to a match table like this. What you should
> do here is use the driver data to point to the const ifs_hw_caps discussed
> before, so what you get here is:
> 
> #define X86_MATCH(model, data)                          \
>         X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6,    \
>                 INTEL_FAM6_##model, X86_FEATURE_CORE_CAPABILITIES, (unsigned long)(data))
> 
> static const struct ifs_hw_caps saphire_rapids_caps = {
> 	.integrity_cap_bit = MSR_INTEGRITY_CAPS_PERIODIC_BIST_BIT,
> 	.test_num = 0,
> };
> 
> static const struct ifs_hw_caps emerald_rapids_caps = {
> 	.integrity_cap_bit = MSR_INTEGRITY_CAPS_PERIODIC_BIST_BIT,
> 	.test_num = 0,
> };
> 
> static const struct x86_cpu_id ifs_cpu_ids[] __initconst = {
> 	X86_MATCH(SAPPHIRERAPIDS_X, &saphire_rapids_caps),
> 	X86_MATCH(EMERALDRAPIDS_X, &emerald_rapids_caps),
> 	{}
> };
> MODULE_DEVICE_TABLE(x86cpu, ifs_cpu_ids);
> 
> and then drop all the code related to having an array of ifs_device structs
> (of which only 1 will ever get used) and instead at the beginning of
> ifs_init(void), after:
> 
>         m = x86_match_cpu(ifs_cpu_ids);
>         if (!m)
>                 return -ENODEV;
> 
> add:
> 
> 	ifs_device.hwcaps = (const struct ifs_hw_caps *)m->driver_data;
> 
> And then you can pretty much drop all the rest of this patch and we
> end up with much nicer code for differentiating between the models :)

Upon reading the rest of the series, I think the above might be based
on me misunderstanding this bit.

If I understand things correctly then what is new with emerald_rapids
is support for a second set/type of tests called " Array Scan test"
and the old test method / test-type is also still supported.

And you have chosen to register 2 misc-devices , one per supported
test type ?

Have I understood that correcty?

May I ask why use 1 misc device per test-type. Why not just add
a single new sysfs_attr to the existing misc device to trigger
the new test-type ?

Regards,

Hans


>> @@ -24,23 +25,51 @@ ATTRIBUTE_GROUPS(plat_ifs);
>>  
>>  bool *ifs_pkg_auth;
>>  
>> -static struct ifs_device ifs_device = {
>> -	.ro_data = {
>> -		.integrity_cap_bit = MSR_INTEGRITY_CAPS_PERIODIC_BIST_BIT,
>> -		.test_num = 0,
>> +static struct ifs_device ifs_devices[] = {
>> +	[IFS_TYPE_SAF] = {
>> +		.ro_data = {
>> +			.integrity_cap_bit = MSR_INTEGRITY_CAPS_PERIODIC_BIST_BIT,
>> +			.test_num = IFS_TYPE_SAF,
>> +		},
>> +		.misc = {
>> +			.name = "intel_ifs_0",
>> +			.minor = MISC_DYNAMIC_MINOR,
>> +			.groups = plat_ifs_groups,
>> +		},
>>  	},
>> -	.misc = {
>> -		.name = "intel_ifs_0",
>> -		.minor = MISC_DYNAMIC_MINOR,
>> -		.groups = plat_ifs_groups,
>> +	[IFS_TYPE_ARRAY_BIST] = {
>> +		.ro_data = {
>> +			.integrity_cap_bit = MSR_INTEGRITY_CAPS_ARRAY_BIST_BIT,
>> +			.test_num = IFS_TYPE_ARRAY_BIST,
>> +		},
>> +		.misc = {
>> +			.name = "intel_ifs_1",
>> +			.minor = MISC_DYNAMIC_MINOR,
>> +		},
>>  	},
>>  };
>>  
>> +#define IFS_NUMTESTS ARRAY_SIZE(ifs_devices)
>> +
>> +static void ifs_cleanup(void)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < IFS_NUMTESTS; i++) {
>> +		if (ifs_devices[i].misc.this_device) {
>> +			misc_deregister(&ifs_devices[i].misc);
>> +			kfree(ifs_devices[i].rw_data);
>> +		}
>> +	}
>> +	kfree(ifs_pkg_auth);
>> +}
>> +
>>  static int __init ifs_init(void)
>>  {
>>  	const struct x86_cpu_id *m;
>>  	struct ifs_data *ifsd;
>>  	u64 msrval;
>> +	int i, ret;
>>  
>>  	m = x86_match_cpu(ifs_cpu_ids);
>>  	if (!m)
>> @@ -55,35 +84,39 @@ static int __init ifs_init(void)
>>  	if (rdmsrl_safe(MSR_INTEGRITY_CAPS, &msrval))
>>  		return -ENODEV;
>>  
>> -	if (!(msrval & BIT(ifs_device.ro_data.integrity_cap_bit)))
>> -		return -ENODEV;
>> -
>>  	ifs_pkg_auth = kmalloc_array(topology_max_packages(), sizeof(bool), GFP_KERNEL);
>>  	if (!ifs_pkg_auth)
>>  		return -ENOMEM;
>>  
>> -	ifsd = kzalloc(sizeof(*ifsd), GFP_KERNEL);
>> -	if (!ifsd)
>> -		return -ENOMEM;
>> -
>> -	ifsd->ro_info = &ifs_device.ro_data;
>> -	ifs_device.rw_data = ifsd;
>> -
>> -	if (misc_register(&ifs_device.misc)) {
>> -		kfree(ifsd);
>> -		kfree(ifs_pkg_auth);
>> -		return -ENODEV;
>> +	for (i = 0; i < IFS_NUMTESTS; i++) {
>> +		ifsd = NULL;
>> +		if (!(msrval & BIT(ifs_devices[i].ro_data.integrity_cap_bit)))
>> +			continue;
>> +
>> +		ifsd = kzalloc(sizeof(*ifsd), GFP_KERNEL);
>> +		if (!ifsd) {
>> +			ret = -ENOMEM;
>> +			goto err_exit;
>> +		}
>> +		ifsd->ro_info = &ifs_devices[i].ro_data;
>> +		ifs_devices[i].rw_data = ifsd;
>> +
>> +		if (misc_register(&ifs_devices[i].misc)) {
>> +			ret = -ENODEV;
>> +			kfree(ifsd);
>> +			goto err_exit;
>> +		}
>>  	}
>> -
>>  	return 0;
>>  
>> +err_exit:
>> +	ifs_cleanup();
>> +	return ret;
>>  }
>>  
>>  static void __exit ifs_exit(void)
>>  {
>> -	misc_deregister(&ifs_device.misc);
>> -	kfree(ifs_device.rw_data);
>> -	kfree(ifs_pkg_auth);
>> +	ifs_cleanup();
>>  }
>>  
>>  module_init(ifs_init);