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Message-ID: <a2ad65a0-7c90-45ae-bb13-e4a3e8a58dae@linux.intel.com>
Date: Thu, 22 Jan 2026 12:29:04 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: "David E. Box" <david.e.box@...ux.intel.com>
cc: thomas.hellstrom@...ux.intel.com, rodrigo.vivi@...el.com,
irenic.rajneesh@...il.com, srinivas.pandruvada@...ux.intel.com,
intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
xi.pardee@...ux.intel.com, Hans de Goede <hansg@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v3 6/6] platform/x86/intel/vsec: Plumb ACPI PMT discovery
tables through vsec
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@...ux.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 */
>
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