linux-kernel - Re: [PATCH 04/10] platform/x86/intel/ifs: Scan test for new generations

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Date:   Fri, 15 Sep 2023 19:51:32 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Jithu Joseph <jithu.joseph@...el.com>
cc:     hdegoede@...hat.com, markgross@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, rostedt@...dmis.org,
        ashok.raj@...el.com, tony.luck@...el.com,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        patches@...ts.linux.dev, ravi.v.shankar@...el.com,
        pengfei.xu@...el.com
Subject: Re: [PATCH 04/10] platform/x86/intel/ifs: Scan test for new
 generations

On Wed, 13 Sep 2023, Jithu Joseph wrote:

> Make changes to scan test flow such that MSRs are populated
> appropriately based on the generation supported by hardware.
> 
> Width of chunk related bitfields is ACTIVATE_SCAN and SCAN_STATUS MSRs
> are different in newer IFS generation compared to gen0.
> 
> Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Tested-by: Pengfei Xu <pengfei.xu@...el.com>
> ---
>  drivers/platform/x86/intel/ifs/ifs.h     | 14 ++++++++++++++
>  drivers/platform/x86/intel/ifs/runtest.c | 23 ++++++++++++++++++-----
>  2 files changed, 32 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
> index 886dc74de57d..3265a6d8a6f3 100644
> --- a/drivers/platform/x86/intel/ifs/ifs.h
> +++ b/drivers/platform/x86/intel/ifs/ifs.h
> @@ -205,6 +205,12 @@ union ifs_scan {
>  		u32	delay	:31;
>  		u32	sigmce	:1;
>  	};
> +	struct {
> +		u16	start;
> +		u16	stop;
> +		u32	delay	:31;
> +		u32	sigmce	:1;
> +	} gen2;

I don't like the way old struct is left without genx naming. It makes the 
code below more confusing as is.

>  };
>  
>  /* MSR_SCAN_STATUS bit fields */
> @@ -219,6 +225,14 @@ union ifs_status {
>  		u32	control_error		:1;
>  		u32	signature_error		:1;
>  	};
> +	struct {
> +		u16	chunk_num;
> +		u16	chunk_stop_index;
> +		u8	error_code;
> +		u32	rsvd1			:22;
> +		u32	control_error		:1;
> +		u32	signature_error		:1;

Again, I don't think the alignment will be correct in this case.

> +	} gen2;
>  };
>  
>  /* MSR_ARRAY_BIST bit fields */
> diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c
> index 1061eb7ec399..4bbab6be2fa2 100644
> --- a/drivers/platform/x86/intel/ifs/runtest.c
> +++ b/drivers/platform/x86/intel/ifs/runtest.c
> @@ -171,6 +171,8 @@ 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;
>  
> @@ -179,13 +181,21 @@ static void ifs_test_core(int cpu, struct device *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.start = to_start;
> +		activate.stop = to_stop;
> +	}
>  
>  	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;
> @@ -202,7 +212,8 @@ static void ifs_test_core(int cpu, struct device *dev)
>  		if (!can_restart(status))
>  			break;
>  
> -		if (status.chunk_num == activate.start) {
> +		status_chunk = ifsd->generation ? status.gen2.chunk_num : status.chunk_num;
> +		if (status_chunk == to_start) {
>  			/* Check for forward progress */
>  			if (--retries == 0) {
>  				if (status.error_code == IFS_NO_ERROR)
> @@ -211,7 +222,9 @@ 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.start = status_chunk);

Misaligned.

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

-- 
 i.