Re: [PATCH 14/15] platform/x86/intel/pmt/telemetry: Add API to retrieve telemetry regions by feature

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

On Wed, 30 Apr 2025, David E. Box wrote:

> Introduce a new API, intel_pmt_get_regions_by_feature(), that gathers
> telemetry regions based on a provided capability flag. This API enables
> retrieval of regions with various capabilities (for example, RMID-based
> telemetry) and provides a unified interface for accessing them. Resource
> management is handled via reference counting using
> intel_pmt_put_feature_group().
> 
> Signed-off-by: David E. Box <david.e.box@linux.intel.com>
> ---
>  drivers/platform/x86/intel/pmt/telemetry.c | 89 +++++++++++++++++++++-
>  include/linux/intel_vsec.h                 | 15 ++++
>  2 files changed, 103 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel/pmt/telemetry.c b/drivers/platform/x86/intel/pmt/telemetry.c
> index 58d06749e417..d071dca4a689 100644
> --- a/drivers/platform/x86/intel/pmt/telemetry.c
> +++ b/drivers/platform/x86/intel/pmt/telemetry.c
> @@ -9,16 +9,20 @@
>   */
>  
>  #include <linux/auxiliary_bus.h>
> +#include <linux/bitops.h>
> +#include <linux/err.h>
>  #include <linux/intel_pmt_features.h>
>  #include <linux/intel_vsec.h>
>  #include <linux/kernel.h>
>  #include <linux/kref.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/overflow.h>
>  #include <linux/pci.h>
>  #include <linux/slab.h>
>  #include <linux/types.h>
>  #include <linux/uaccess.h>
> -#include <linux/overflow.h>
> +#include <linux/xarray.h>
>  
>  #include "class.h"
>  
> @@ -209,6 +213,88 @@ int pmt_telem_get_endpoint_info(int devid, struct telem_endpoint_info *info)
>  }
>  EXPORT_SYMBOL_NS_GPL(pmt_telem_get_endpoint_info, "INTEL_PMT_TELEMETRY");
>  
> +static int pmt_copy_region(struct telemetry_region *region,
> +			   struct intel_pmt_entry *entry)
> +{
> +
> +	struct oobmsm_plat_info *plat_info;
> +
> +	plat_info = intel_vsec_get_mapping(entry->ep->pcidev);
> +	if (IS_ERR(plat_info))
> +		return PTR_ERR(plat_info);
> +
> +	region->plat_info = *plat_info;
> +	region->guid = entry->guid;
> +	region->addr = entry->ep->base;
> +	region->size = entry->size;
> +	region->num_rmids = entry->num_rmids;
> +
> +	return 0;
> +}
> +
> +static void pmt_feature_group_release(struct kref *kref)
> +{
> +	struct pmt_feature_group *feature_group;
> +
> +	feature_group = container_of(kref, struct pmt_feature_group, kref);
> +	kfree(feature_group);
> +}
> +
> +struct pmt_feature_group *intel_pmt_get_regions_by_feature(enum pmt_feature_id id)
> +{
> +	struct pmt_feature_group *feature_group;
> +	struct telemetry_region *region;
> +	struct intel_pmt_entry *entry;
> +	unsigned long idx;
> +	int count = 0;
> +	size_t size;
> +
> +	if (!pmt_feature_id_is_valid(id))
> +		return ERR_PTR(-EINVAL);
> +
> +	guard(mutex)(&ep_lock);
> +	xa_for_each(&telem_array, idx, entry) {
> +		if (entry->feature_flags & BIT(id))
> +			count++;
> +	}
> +
> +	if (!count)
> +		return ERR_PTR(-ENOENT);
> +
> +	size = struct_size(feature_group, regions, count);
> +	feature_group = kzalloc(size, GFP_KERNEL);
> +	if (!feature_group)
> +		return ERR_PTR(-ENOMEM);
> +
> +	feature_group->count = count;
> +
> +	region = feature_group->regions;
> +	xa_for_each(&telem_array, idx, entry) {
> +		int ret;
> +
> +		if (!(entry->feature_flags & BIT(id)))
> +			continue;
> +
> +		ret = pmt_copy_region(region, entry);
> +		if (ret) {
> +			kfree(feature_group);

Use __free() instead.

> +			return ERR_PTR(ret);
> +		}
> +		region++;
> +	}
> +
> +	kref_init(&feature_group->kref);
> +
> +	return feature_group;
> +}
> +EXPORT_SYMBOL(intel_pmt_get_regions_by_feature);
> +
> +void intel_pmt_put_feature_group(struct pmt_feature_group *feature_group)
> +{
> +	kref_put(&feature_group->kref, pmt_feature_group_release);
> +}
> +EXPORT_SYMBOL(intel_pmt_put_feature_group);
> +
>  int pmt_telem_read(struct telem_endpoint *ep, u32 id, u64 *data, u32 count)
>  {
>  	u32 offset, size;
> @@ -353,3 +439,4 @@ MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
>  MODULE_DESCRIPTION("Intel PMT Telemetry driver");
>  MODULE_LICENSE("GPL v2");
>  MODULE_IMPORT_NS("INTEL_PMT");
> +MODULE_IMPORT_NS("INTEL_VSEC");
> diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
> index f63e67398a8e..f41d2ec974fd 100644
> --- a/include/linux/intel_vsec.h
> +++ b/include/linux/intel_vsec.h
> @@ -220,4 +220,19 @@ static inline struct oobmsm_plat_info *intel_vsec_get_mapping(struct pci_dev *pd
>  	return ERR_PTR(-ENODEV);
>  }
>  #endif
> +
> +#if IS_ENABLED(CONFIG_INTEL_PMT_TELEMETRY)
> +struct pmt_feature_group *
> +intel_pmt_get_regions_by_feature(enum pmt_feature_id id);
> +
> +void intel_pmt_put_feature_group(struct pmt_feature_group *feature_group);
> +#else
> +static inline struct pmt_feature_group *
> +intel_pmt_get_regions_by_feature(enum pmt_feature_id id)
> +{ return ERR_PTR(-ENODEV); }

Please add include for ERR_PTR().

Change this to follow the normal function coding style even if it takes
2 lines more that way. :-)

> +
> +static inline void
> +intel_pmt_put_feature_group(struct pmt_feature_group *feature_group) {}
> +#endif
> +
>  #endif
> 

-- 
 i.