Re: [PATCH v2 4/9] platform/x86/intel/ifs: Gen2 Scan test support

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Fri, 22 Sep 2023, Jithu Joseph wrote:

> Width of chunk related bitfields is ACTIVATE_SCAN and SCAN_STATUS MSRs
> are different in newer IFS generation compared to gen0.
> 
> Make changes to scan test flow such that MSRs are populated
> appropriately based on the generation supported by hardware.
> 
> Account for the 8/16 bit MSR bitfield width differences between gen0 and
> newer generations for the scan test trace event too.
> 
> Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> Tested-by: Pengfei Xu <pengfei.xu@intel.com>
> ---
>  drivers/platform/x86/intel/ifs/ifs.h     | 28 +++++++++++++++++++-----
>  include/trace/events/intel_ifs.h         | 16 +++++++-------
>  drivers/platform/x86/intel/ifs/runtest.c | 26 ++++++++++++++++------
>  3 files changed, 49 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
> index 43281d456a09..cd213b89d278 100644
> --- a/drivers/platform/x86/intel/ifs/ifs.h
> +++ b/drivers/platform/x86/intel/ifs/ifs.h
> @@ -199,9 +199,17 @@ union ifs_chunks_auth_status_gen2 {
>  union ifs_scan {
>  	u64	data;
>  	struct {
> -		u32	start	:8;
> -		u32	stop	:8;
> -		u32	rsvd	:16;
> +		union {
> +			struct {
> +				u8	start;
> +				u8	stop;
> +				u16	rsvd;
> +			} gen0;
> +			struct {
> +				u16	start;
> +				u16	stop;
> +			} gen2;
> +		};
>  		u32	delay	:31;
>  		u32	sigmce	:1;
>  	};
> @@ -211,9 +219,17 @@ union ifs_scan {
>  union ifs_status {
>  	u64	data;
>  	struct {
> -		u32	chunk_num		:8;
> -		u32	chunk_stop_index	:8;
> -		u32	rsvd1			:16;
> +		union {
> +			struct {
> +				u8	chunk_num;
> +				u8	chunk_stop_index;
> +				u16	rsvd1;
> +			} gen0;
> +			struct {
> +				u16	chunk_num;
> +				u16	chunk_stop_index;
> +			} gen2;
> +		};
>  		u32	error_code		:8;
>  		u32	rsvd2			:22;
>  		u32	control_error		:1;
> diff --git a/include/trace/events/intel_ifs.h b/include/trace/events/intel_ifs.h
> index d7353024016c..af0af3f1d9b7 100644
> --- a/include/trace/events/intel_ifs.h
> +++ b/include/trace/events/intel_ifs.h
> @@ -10,25 +10,25 @@
>  
>  TRACE_EVENT(ifs_status,
>  
> -	TP_PROTO(int cpu, union ifs_scan activate, union ifs_status status),
> +	TP_PROTO(int cpu, int start, int stop, u64 status),
>  
> -	TP_ARGS(cpu, activate, status),
> +	TP_ARGS(cpu, start, stop, status),
>  
>  	TP_STRUCT__entry(
>  		__field(	u64,	status	)
>  		__field(	int,	cpu	)
> -		__field(	u8,	start	)
> -		__field(	u8,	stop	)
> +		__field(	u16,	start	)
> +		__field(	u16,	stop	)
>  	),
>  
>  	TP_fast_assign(
>  		__entry->cpu	= cpu;
> -		__entry->start	= activate.start;
> -		__entry->stop	= activate.stop;
> -		__entry->status	= status.data;
> +		__entry->start	= start;
> +		__entry->stop	= stop;
> +		__entry->status	= status;
>  	),
>  
> -	TP_printk("cpu: %d, start: %.2x, stop: %.2x, status: %llx",
> +	TP_printk("cpu: %d, start: %.4x, stop: %.4x, status: %.16llx",
>  		__entry->cpu,
>  		__entry->start,
>  		__entry->stop,
> diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c
> index 1061eb7ec399..94d486e5d263 100644
> --- a/drivers/platform/x86/intel/ifs/runtest.c
> +++ b/drivers/platform/x86/intel/ifs/runtest.c
> @@ -171,21 +171,30 @@ static void ifs_test_core(int cpu, struct device *dev)
>  	union ifs_status status;
>  	unsigned long timeout;
>  	struct ifs_data *ifsd;
> +	int to_start, to_stop;
> +	int status_chunk;
>  	u64 msrvals[2];
>  	int retries;
>  
>  	ifsd = ifs_get_data(dev);
>  
> -	activate.rsvd = 0;
>  	activate.delay = IFS_THREAD_WAIT;
>  	activate.sigmce = 0;
> -	activate.start = 0;
> -	activate.stop = ifsd->valid_chunks - 1;
> +	to_start = 0;
> +	to_stop = ifsd->valid_chunks - 1;
> +
> +	if (ifsd->generation) {
> +		activate.gen2.start = to_start;
> +		activate.gen2.stop = to_stop;
> +	} else {
> +		activate.gen0.start = to_start;
> +		activate.gen0.stop = to_stop;
> +	}

Is it okay to not do activate.gen0.rsvd = 0 anymore? If you know it is, it 
would be nice to record that fact into the changelog so that it can be 
found in the history.

>  
>  	timeout = jiffies + HZ / 2;
>  	retries = MAX_IFS_RETRIES;
>  
> -	while (activate.start <= activate.stop) {
> +	while (to_start <= to_stop) {
>  		if (time_after(jiffies, timeout)) {
>  			status.error_code = IFS_SW_TIMEOUT;
>  			break;
> @@ -196,13 +205,14 @@ static void ifs_test_core(int cpu, struct device *dev)
>  
>  		status.data = msrvals[1];
>  
> -		trace_ifs_status(cpu, activate, status);
> +		trace_ifs_status(cpu, to_start, to_stop, status.data);
>  
>  		/* Some cases can be retried, give up for others */
>  		if (!can_restart(status))
>  			break;
>  
> -		if (status.chunk_num == activate.start) {
> +		status_chunk = ifsd->generation ? status.gen2.chunk_num : status.gen0.chunk_num;
> +		if (status_chunk == to_start) {
>  			/* Check for forward progress */
>  			if (--retries == 0) {
>  				if (status.error_code == IFS_NO_ERROR)
> @@ -211,7 +221,9 @@ static void ifs_test_core(int cpu, struct device *dev)
>  			}
>  		} else {
>  			retries = MAX_IFS_RETRIES;
> -			activate.start = status.chunk_num;
> +			ifsd->generation ? (activate.gen2.start = status_chunk) :
> +			(activate.gen0.start = status_chunk);

The alignment of the second line is still not correct but now I notice how 
the left-hand side is hidden within those expressions. Just do a normal if 
instead so that it is simpler to understand, please.

> +			to_start = status_chunk;
>  		}
>  	}
>  
> 

-- 
 i.