Re: [PATCH 6/8] platform/x86/intel/sdsi: Add attribute to read the current meter state

Ilpo Järvinen
2024-02-08T14:43:49Z

On Wed, 31 Jan 2024, 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@linux.intel.com>
> ---
> drivers/platform/x86/intel/sdsi.c | 42 ++++++++++++++++++++++++++++---
> drivers/platform/x86/intel/sdsi.h | 2 ++
> 2 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/platform/x86/intel/sdsi.c b/drivers/platform/x86/intel/sdsi.c
> index 287780fe65bb..171899b4a671 100644
> --- a/drivers/platform/x86/intel/sdsi.c
> +++ b/drivers/platform/x86/intel/sdsi.c
> @@ -62,6 +62,7 @@
> #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)
> @@ -235,8 +236,10 @@ 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) |
> + priv->control_flags;
> writeq(control, priv->control_addr);
> + priv->control_flags = 0;

I'm slightly worried about this. The function is named with a generic
name but I suppose meter_lock that has less generic name is supposed to
protect this also?

Also, resetting it after every use smells like it should be a parameter
instead of struct member.

> return sdsi_mbox_poll(priv, info, data_size);
> }
> @@ -468,11 +471,42 @@ meter_certificate_read(struct file *filp, struct kobject *kobj,
> {
> struct device *dev = kobj_to_dev(kobj);
> struct sdsi_priv *priv = dev_get_drvdata(dev);
> + int ret;
>
> - return certificate_read(SDSI_CMD_READ_METER, priv, buf, off, count);
> + ret = mutex_lock_interruptible(&priv->meter_lock);
> + if (ret)
> + return ret;
> +
> + ret = certificate_read(SDSI_CMD_READ_METER, priv, buf, off, count);
> +
> + mutex_unlock(&priv->meter_lock);
> +
> + return ret;
> }
> 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);
> + int ret;
> +
> + ret = mutex_lock_interruptible(&priv->meter_lock);
> + if (ret)
> + return ret;
> +
> + priv->control_flags = CTRL_METER_ENABLE_DRAM;
> + ret = certificate_read(SDSI_CMD_READ_METER, priv, buf, off, count);
> +
> + mutex_unlock(&priv->meter_lock);
> +
> + return ret;
> +}
> +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)
> @@ -503,6 +537,7 @@ 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
> @@ -522,7 +557,7 @@ 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;
>
> @@ -725,6 +760,7 @@ static int sdsi_probe(struct auxiliary_device *auxdev, const struct auxiliary_de
> priv->dev = &auxdev->dev;
> priv->id = auxdev->id;
> mutex_init(&priv->mb_lock);
> + mutex_init(&priv->meter_lock);
> auxiliary_set_drvdata(auxdev, priv);
>
> /* Get the SDSi discovery table */
> diff --git a/drivers/platform/x86/intel/sdsi.h b/drivers/platform/x86/intel/sdsi.h
> index 256618eb3136..e20cf279212e 100644
> --- a/drivers/platform/x86/intel/sdsi.h
> +++ b/drivers/platform/x86/intel/sdsi.h
> @@ -18,12 +18,14 @@ struct device;
>
> struct sdsi_priv {
> struct mutex mb_lock; /* Mailbox access lock */
> + struct mutex meter_lock;

Please add information what this protects.

--
i.