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Message-ID: <tuitjp3fhclpfu4qhf7zz37yqaltqgca45ibsyhycgi7kqtzlx@i7dkq3gjwi4c>
Date: Thu, 22 Jan 2026 07:42:15 -0800
From: David Box <david.e.box@...ux.intel.com>
To: Ilpo Järvinen <ilpo.jarvinen@...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 Thu, Jan 22, 2026 at 12:29:04PM +0200, Ilpo Järvinen wrote:
> 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?
Yep. Went with array_size() but was thinking check_mul_overflow(). Will
update. Thanks.
David
>
> 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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