Re: [PATCH v3 6/6] platform/x86/intel/vsec: Plumb ACPI PMT discovery tables through vsec

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

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On Wed, 21 Jan 2026, David E. Box wrote:

> Some platforms expose PMT discovery via ACPI instead of PCI BARs. Add a
> generic discovery source flag and carry ACPI discovery entries alongside
> the existing PCI resource path so PMT clients can consume either.
> 
> Changes:
>   - Add enum intel_vsec_disc_source { _PCI, _ACPI }.
>   - Extend intel_vsec_platform_info and intel_vsec_device with source enum
>     and ACPI discovery table pointer/
>   - When src==ACPI, skip BAR resource setup and copy the ACPI discovery
>     entries into the aux device.
> 
> No user-visible behavior change yet; this only wires ACPI data through vsec
> in preparation for ACPI-enumerated PMT clients.
> 
> Signed-off-by: David E. Box <david.e.box@linux.intel.com>
> ---
> 
> v3:
>   - Re-send with all changes intended for v2 which was sent without them
>     being applied.
> 
> v2:
>   - Improve comment to clarify BAR resource setup doesn't apply to ACPI
>     discovery
>   - Add missing #include for kmemdup()
>   - Use array_size() for overflow protection
>     (review comments by Ilpo Järvinen)
> 
> 
>  drivers/platform/x86/intel/vsec.c | 24 ++++++++++++++++++++++++
>  include/linux/intel_vsec.h        | 20 +++++++++++++++++++-
>  2 files changed, 43 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel/vsec.c b/drivers/platform/x86/intel/vsec.c
> index 4aeb0728b435..b1465e67feef 100644
> --- a/drivers/platform/x86/intel/vsec.c
> +++ b/drivers/platform/x86/intel/vsec.c
> @@ -24,7 +24,9 @@
>  #include <linux/intel_vsec.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/overflow.h>
>  #include <linux/pci.h>
> +#include <linux/string.h>
>  #include <linux/types.h>
>  
>  #define PMT_XA_START			0
> @@ -109,6 +111,7 @@ static void intel_vsec_dev_release(struct device *dev)
>  
>  	ida_free(intel_vsec_dev->ida, intel_vsec_dev->auxdev.id);
>  
> +	kfree(intel_vsec_dev->acpi_disc);
>  	kfree(intel_vsec_dev->resource);
>  	kfree(intel_vsec_dev);
>  }
> @@ -320,6 +323,13 @@ static int intel_vsec_add_dev(struct device *dev, struct intel_vsec_header *head
>  	 * auxiliary device driver.
>  	 */
>  	for (i = 0, tmp = res; i < header->num_entries; i++, tmp++) {
> +		/*
> +		 * Skip resource mapping check for ACPI-based discovery
> +		 * since those tables are read from _DSD, not MMIO.
> +		 */
> +		if (info->src == INTEL_VSEC_DISC_ACPI)
> +			break;
> +
>  		tmp->start = base_addr + header->offset + i * (header->entry_size * sizeof(u32));
>  		tmp->end = tmp->start + (header->entry_size * sizeof(u32)) - 1;
>  		tmp->flags = IORESOURCE_MEM;
> @@ -338,6 +348,20 @@ static int intel_vsec_add_dev(struct device *dev, struct intel_vsec_header *head
>  	intel_vsec_dev->base_addr = info->base_addr;
>  	intel_vsec_dev->priv_data = info->priv_data;
>  	intel_vsec_dev->cap_id = cap_id;
> +	intel_vsec_dev->src = info->src;
> +
> +	if (info->src == INTEL_VSEC_DISC_ACPI) {
> +		size_t bytes;
> +
> +		bytes = array_size(intel_vsec_dev->num_resources,
> +				   sizeof(info->acpi_disc[0]));
> +		if (!bytes)
> +			return -EOVERFLOW;

Is this correct as array_size() is documented to return SIZE_MAX on 
overflow?

Other than that, this series looked very straightforward now.

-- 
 i.

> +
> +		intel_vsec_dev->acpi_disc = kmemdup(info->acpi_disc, bytes, GFP_KERNEL);
> +		if (!intel_vsec_dev->acpi_disc)
> +			return -ENOMEM;
> +	}
>  
>  	if (header->id == VSEC_ID_SDSI)
>  		intel_vsec_dev->ida = &intel_vsec_sdsi_ida;
> diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
> index 4eecb2a6bac4..1fe5665a9d02 100644
> --- a/include/linux/intel_vsec.h
> +++ b/include/linux/intel_vsec.h
> @@ -33,6 +33,11 @@ struct device;
>  struct pci_dev;
>  struct resource;
>  
> +enum intel_vsec_disc_source {
> +	INTEL_VSEC_DISC_PCI,	/* PCI, default */
> +	INTEL_VSEC_DISC_ACPI,	/* ACPI */
> +};
> +
>  enum intel_vsec_id {
>  	VSEC_ID_TELEMETRY	= 2,
>  	VSEC_ID_WATCHER		= 3,
> @@ -103,6 +108,10 @@ struct vsec_feature_dependency {
>   * @parent:    parent device in the auxbus chain
>   * @headers:   list of headers to define the PMT client devices to create
>   * @deps:      array of feature dependencies
> + * @acpi_disc: ACPI discovery tables, each entry is two QWORDs
> + *             in little-endian format as defined by the PMT ACPI spec.
> + *             Valid only when @provider == INTEL_VSEC_DISC_ACPI.
> + * @src:       source of discovery table data
>   * @priv_data: private data, usable by parent devices, currently a callback
>   * @caps:      bitmask of PMT capabilities for the given headers
>   * @quirks:    bitmask of VSEC device quirks
> @@ -113,6 +122,8 @@ struct intel_vsec_platform_info {
>  	struct device *parent;
>  	struct intel_vsec_header **headers;
>  	const struct vsec_feature_dependency *deps;
> +	u32 (*acpi_disc)[4];
> +	enum intel_vsec_disc_source src;
>  	void *priv_data;
>  	unsigned long caps;
>  	unsigned long quirks;
> @@ -124,7 +135,12 @@ struct intel_vsec_platform_info {
>   * struct intel_vsec_device - Auxbus specific device information
>   * @auxdev:        auxbus device struct for auxbus access
>   * @dev:           struct device associated with the device
> - * @resource:      any resources shared by the parent
> + * @resource:      PCI discovery resources (BAR windows), one per discovery
> + *                 instance. Valid only when @src == INTEL_VSEC_DISC_PCI
> + * @acpi_disc:     ACPI discovery tables, each entry is two QWORDs
> + *                 in little-endian format as defined by the PMT ACPI spec.
> + *                 Valid only when @src == INTEL_VSEC_DISC_ACPI.
> + * @src:           source of discovery table data
>   * @ida:           id reference
>   * @num_resources: number of resources
>   * @id:            xarray id
> @@ -138,6 +154,8 @@ struct intel_vsec_device {
>  	struct auxiliary_device auxdev;
>  	struct device *dev;
>  	struct resource *resource;
> +	u32 (*acpi_disc)[4];
> +	enum intel_vsec_disc_source src;
>  	struct ida *ida;
>  	int num_resources;
>  	int id; /* xa */
>