Re: [PATCH V2 4/9] platform/x86/intel/sdsi: Add attribute to read the current meter state

[Kuppuswamy Sathyanarayanan]

On 2/27/24 4:00 PM, David E. Box wrote:
> The meter_certificate file provides access to metering information that may
> be attested but is only updated every 8 hours. Add new attribute,
> meter_current, to allow reading an untested snapshot of the current values.
>
> Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
> ---

Looks good to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

>
> V2 - make control_flags a parameter to be eventually passed to
>      sdsi_mbox_cmd_read(). This removes the need for a lock which had been
>      added to protect control_flags when it was a member of the private
>      struct.
>
>  drivers/platform/x86/intel/sdsi.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/platform/x86/intel/sdsi.c b/drivers/platform/x86/intel/sdsi.c
> index bb3eaf5eb382..277e4f4b20ac 100644
> --- a/drivers/platform/x86/intel/sdsi.c
> +++ b/drivers/platform/x86/intel/sdsi.c
> @@ -68,6 +68,7 @@
>  #define CTRL_COMPLETE			BIT(6)
>  #define CTRL_READY			BIT(7)
>  #define CTRL_INBAND_LOCK		BIT(32)
> +#define CTRL_METER_ENABLE_DRAM		BIT(33)
>  #define CTRL_STATUS			GENMASK(15, 8)
>  #define CTRL_PACKET_SIZE		GENMASK(31, 16)
>  #define CTRL_MSG_SIZE			GENMASK(63, 48)
> @@ -95,6 +96,7 @@ enum sdsi_command {
>  struct sdsi_mbox_info {
>  	u64	*payload;
>  	void	*buffer;
> +	u64	control_flags;
>  	int	size;
>  };
>  
> @@ -250,7 +252,8 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox_info *inf
>  	control = FIELD_PREP(CTRL_EOM, 1) |
>  		  FIELD_PREP(CTRL_SOM, 1) |
>  		  FIELD_PREP(CTRL_RUN_BUSY, 1) |
> -		  FIELD_PREP(CTRL_PACKET_SIZE, info->size);
> +		  FIELD_PREP(CTRL_PACKET_SIZE, info->size) |
> +		  info->control_flags;
>  	writeq(control, priv->control_addr);
>  
>  	return sdsi_mbox_poll(priv, info, data_size);
> @@ -424,8 +427,8 @@ static ssize_t provision_cap_write(struct file *filp, struct kobject *kobj,
>  static BIN_ATTR_WO(provision_cap, SDSI_SIZE_WRITE_MSG);
>  
>  static ssize_t
> -certificate_read(u64 command, struct sdsi_priv *priv, char *buf, loff_t off,
> -		 size_t count)
> +certificate_read(u64 command, u64 control_flags, struct sdsi_priv *priv,
> +		 char *buf, loff_t off, size_t count)
>  {
>  	struct sdsi_mbox_info info = {};
>  	size_t size;
> @@ -441,6 +444,7 @@ certificate_read(u64 command, struct sdsi_priv *priv, char *buf, loff_t off,
>  
>  	info.payload = &command;
>  	info.size = sizeof(command);
> +	info.control_flags = control_flags;
>  
>  	ret = mutex_lock_interruptible(&priv->mb_lock);
>  	if (ret)
> @@ -472,7 +476,7 @@ state_certificate_read(struct file *filp, struct kobject *kobj,
>  	struct device *dev = kobj_to_dev(kobj);
>  	struct sdsi_priv *priv = dev_get_drvdata(dev);
>  
> -	return certificate_read(SDSI_CMD_READ_STATE, priv, buf, off, count);
> +	return certificate_read(SDSI_CMD_READ_STATE, 0, priv, buf, off, count);
>  }
>  static BIN_ATTR_ADMIN_RO(state_certificate, SDSI_SIZE_READ_MSG);
>  
> @@ -484,10 +488,23 @@ meter_certificate_read(struct file *filp, struct kobject *kobj,
>  	struct device *dev = kobj_to_dev(kobj);
>  	struct sdsi_priv *priv = dev_get_drvdata(dev);
>  
> -	return certificate_read(SDSI_CMD_READ_METER, priv, buf, off, count);
> +	return certificate_read(SDSI_CMD_READ_METER, 0, priv, buf, off, count);
>  }
>  static BIN_ATTR_ADMIN_RO(meter_certificate, SDSI_SIZE_READ_MSG);
>  
> +static ssize_t
> +meter_current_read(struct file *filp, struct kobject *kobj,
> +		   struct bin_attribute *attr, char *buf, loff_t off,
> +		   size_t count)
> +{
> +	struct device *dev = kobj_to_dev(kobj);
> +	struct sdsi_priv *priv = dev_get_drvdata(dev);
> +
> +	return certificate_read(SDSI_CMD_READ_METER, CTRL_METER_ENABLE_DRAM,
> +				priv, buf, off, count);
> +}
> +static BIN_ATTR_ADMIN_RO(meter_current, SDSI_SIZE_READ_MSG);
> +
>  static ssize_t registers_read(struct file *filp, struct kobject *kobj,
>  			      struct bin_attribute *attr, char *buf, loff_t off,
>  			      size_t count)
> @@ -518,6 +535,7 @@ static struct bin_attribute *sdsi_bin_attrs[] = {
>  	&bin_attr_registers,
>  	&bin_attr_state_certificate,
>  	&bin_attr_meter_certificate,
> +	&bin_attr_meter_current,
>  	&bin_attr_provision_akc,
>  	&bin_attr_provision_cap,
>  	NULL
> @@ -537,7 +555,7 @@ sdsi_battr_is_visible(struct kobject *kobj, struct bin_attribute *attr, int n)
>  	if (!(priv->features & SDSI_FEATURE_SDSI))
>  		return 0;
>  
> -	if (attr == &bin_attr_meter_certificate)
> +	if (attr == &bin_attr_meter_certificate || attr == &bin_attr_meter_current)
>  		return (priv->features & SDSI_FEATURE_METERING) ?
>  				attr->attr.mode : 0;
>  

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer