[PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT callbacks

[PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT callbacks

[Michael J. Ruhl]

Usage of the telem sysfs file allows for partial reads at
an offset.

The current callback method returns the buffer starting
from offset 0 only.

Include the requested offset in the callback.
Update the necsessary address calculations with the offset.

Fixes: e92affc74cd8 ("platform/x86/intel/vsec: Add PMT read callbacks")
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
 drivers/platform/x86/intel/pmt/class.c     | 10 +++++-----
 drivers/platform/x86/intel/pmt/class.h     |  2 +-
 drivers/platform/x86/intel/pmt/telemetry.c |  2 +-
 include/linux/intel_vsec.h                 |  3 ++-
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index c04bb7f97a4d..657d72b9e675 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -59,16 +59,16 @@ pmt_memcpy64_fromio(void *to, const u64 __iomem *from, size_t count)
 }
 
 int pmt_telem_read_mmio(struct pci_dev *pdev, struct pmt_callbacks *cb, u32 guid, void *buf,
-			void __iomem *addr, u32 count)
+			void __iomem *addr, loff_t off, u32 count)
 {
 	if (cb && cb->read_telem)
-		return cb->read_telem(pdev, guid, buf, count);
+		return cb->read_telem(pdev, guid, buf, off, count);
 
 	if (guid == GUID_SPR_PUNIT)
 		/* PUNIT on SPR only supports aligned 64-bit read */
-		return pmt_memcpy64_fromio(buf, addr, count);
+		return pmt_memcpy64_fromio(buf, addr + off, count);
 
-	memcpy_fromio(buf, addr, count);
+	memcpy_fromio(buf, addr + off, count);
 
 	return count;
 }
@@ -96,7 +96,7 @@ intel_pmt_read(struct file *filp, struct kobject *kobj,
 		count = entry->size - off;
 
 	count = pmt_telem_read_mmio(entry->ep->pcidev, entry->cb, entry->header.guid, buf,
-				    entry->base + off, count);
+				    entry->base, off, count);
 
 	return count;
 }
diff --git a/drivers/platform/x86/intel/pmt/class.h b/drivers/platform/x86/intel/pmt/class.h
index a267ac964423..b2006d57779d 100644
--- a/drivers/platform/x86/intel/pmt/class.h
+++ b/drivers/platform/x86/intel/pmt/class.h
@@ -62,7 +62,7 @@ struct intel_pmt_namespace {
 };
 
 int pmt_telem_read_mmio(struct pci_dev *pdev, struct pmt_callbacks *cb, u32 guid, void *buf,
-			void __iomem *addr, u32 count);
+			void __iomem *addr, loff_t off, u32 count);
 bool intel_pmt_is_early_client_hw(struct device *dev);
 int intel_pmt_dev_create(struct intel_pmt_entry *entry,
 			 struct intel_pmt_namespace *ns,
diff --git a/drivers/platform/x86/intel/pmt/telemetry.c b/drivers/platform/x86/intel/pmt/telemetry.c
index c9feac859e57..0cea617c6c2e 100644
--- a/drivers/platform/x86/intel/pmt/telemetry.c
+++ b/drivers/platform/x86/intel/pmt/telemetry.c
@@ -219,7 +219,7 @@ int pmt_telem_read(struct telem_endpoint *ep, u32 id, u64 *data, u32 count)
 	if (offset + NUM_BYTES_QWORD(count) > size)
 		return -EINVAL;
 
-	pmt_telem_read_mmio(ep->pcidev, ep->cb, ep->header.guid, data, ep->base + offset,
+	pmt_telem_read_mmio(ep->pcidev, ep->cb, ep->header.guid, data, ep->base, offset,
 			    NUM_BYTES_QWORD(count));
 
 	return ep->present ? 0 : -EPIPE;
diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index 11ee185566c3..b94beab64610 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -74,10 +74,11 @@ enum intel_vsec_quirks {
  * @pdev:  PCI device reference for the callback's use
  * @guid:  ID of data to acccss
  * @data:  buffer for the data to be copied
+ * @off:   offset into the requested buffer
  * @count: size of buffer
  */
 struct pmt_callbacks {
-	int (*read_telem)(struct pci_dev *pdev, u32 guid, u64 *data, u32 count);
+	int (*read_telem)(struct pci_dev *pdev, u32 guid, u64 *data, loff_t off, u32 count);
 };
 
 /**
-- 
2.44.0

[PATCH 2/2] drm/xe/vsec: Support BMG devices

[Michael J. Ruhl]

The Battlemage (BMG) discrete graphics card supports the
Platform, Monitoring Technology (PMT) feature directly
on the primary PCI device.

Utilize the PMT callback API to add support for the BMG
devices.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
 drivers/gpu/drm/xe/Makefile          |   1 +
 drivers/gpu/drm/xe/regs/xe_pmt.h     |  19 +++
 drivers/gpu/drm/xe/xe_device.c       |   5 +
 drivers/gpu/drm/xe/xe_device_types.h |   6 +
 drivers/gpu/drm/xe/xe_vsec.c         | 230 +++++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_vsec.h         |  13 ++
 6 files changed, 274 insertions(+)
 create mode 100644 drivers/gpu/drm/xe/regs/xe_pmt.h
 create mode 100644 drivers/gpu/drm/xe/xe_vsec.c
 create mode 100644 drivers/gpu/drm/xe/xe_vsec.h

diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index a93e6fcc0ad9..7730e0596299 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -111,6 +111,7 @@ xe-y += xe_bb.o \
 	xe_vm.o \
 	xe_vram.o \
 	xe_vram_freq.o \
+	xe_vsec.o \
 	xe_wait_user_fence.o \
 	xe_wa.o \
 	xe_wopcm.o
diff --git a/drivers/gpu/drm/xe/regs/xe_pmt.h b/drivers/gpu/drm/xe/regs/xe_pmt.h
new file mode 100644
index 000000000000..f45abcd96ba8
--- /dev/null
+++ b/drivers/gpu/drm/xe/regs/xe_pmt.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+#ifndef _XE_PMT_H_
+#define _XE_PMT_H_
+
+#define SOC_BASE			0x280000
+
+#define BMG_PMT_BASE_OFFSET		0xDB000
+#define BMG_DISCOVERY_OFFSET		(SOC_BASE + BMG_PMT_BASE_OFFSET)
+
+#define BMG_TELEMETRY_BASE_OFFSET	0xE0000
+#define BMG_TELEMETRY_OFFSET		(SOC_BASE + BMG_TELEMETRY_BASE_OFFSET)
+
+#define SG_REMAP_INDEX1			XE_REG(SOC_BASE + 0x08)
+#define   SG_REMAP_BITS			REG_GENMASK(31, 24)
+
+#endif
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 0e2dd691bdae..daef60122cac 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -55,6 +55,7 @@
 #include "xe_ttm_sys_mgr.h"
 #include "xe_vm.h"
 #include "xe_vram.h"
+#include "xe_vsec.h"
 #include "xe_wait_user_fence.h"
 #include "xe_wa.h"
 
@@ -365,6 +366,8 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
 		goto err;
 	}
 
+	drmm_mutex_init(&xe->drm, &xe->pmt.lock);
+
 	err = xe_display_create(xe);
 	if (WARN_ON(err))
 		goto err;
@@ -759,6 +762,8 @@ int xe_device_probe(struct xe_device *xe)
 	for_each_gt(gt, xe, id)
 		xe_gt_sanitize_freq(gt);
 
+	xe_vsec_init(xe);
+
 	return devm_add_action_or_reset(xe->drm.dev, xe_device_sanitize, xe);
 
 err_fini_display:
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index bccca63c8a48..13164ea2bddb 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -483,6 +483,12 @@ struct xe_device {
 		struct mutex lock;
 	} d3cold;
 
+	/** @pmt: Support the PMT driver callback interface */
+	struct {
+		/** @pmt.lock: protect access for telemetry data */
+		struct mutex lock;
+	} pmt;
+
 	/**
 	 * @pm_callback_task: Track the active task that is running in either
 	 * the runtime_suspend or runtime_resume callbacks.
diff --git a/drivers/gpu/drm/xe/xe_vsec.c b/drivers/gpu/drm/xe/xe_vsec.c
new file mode 100644
index 000000000000..fbd779f912d9
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_vsec.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/cleanup.h>
+#include <linux/intel_vsec.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pci.h>
+
+#include "xe_device.h"
+#include "xe_device_types.h"
+#include "xe_drv.h"
+#include "xe_mmio.h"
+#include "xe_platform_types.h"
+#include "xe_pm.h"
+#include "xe_vsec.h"
+#include "regs/xe_pmt.h"
+
+#define BMG_DEVICE_ID 0xE2F8
+
+static struct intel_vsec_header bmg_telemetry = {
+	.length = 0x10,
+	.id = VSEC_ID_TELEMETRY,
+	.num_entries = 2,
+	.entry_size = 4,
+	.tbir = 0,
+	.offset = BMG_DISCOVERY_OFFSET,
+};
+
+static struct intel_vsec_header bmg_punit_crashlog = {
+	.length = 0x10,
+	.id = VSEC_ID_CRASHLOG,
+	.num_entries = 1,
+	.entry_size = 4,
+	.tbir = 0,
+	.offset = BMG_DISCOVERY_OFFSET + 0x60,
+};
+
+static struct intel_vsec_header bmg_oobmsm_crashlog = {
+	.length = 0x10,
+	.id = VSEC_ID_CRASHLOG,
+	.num_entries = 1,
+	.entry_size = 4,
+	.tbir = 0,
+	.offset = BMG_DISCOVERY_OFFSET + 0x78,
+};
+
+static struct intel_vsec_header *bmg_capabilities[] = {
+	&bmg_telemetry,
+	&bmg_punit_crashlog,
+	&bmg_oobmsm_crashlog,
+	NULL
+};
+
+enum xe_vsec {
+	XE_VSEC_UNKNOWN = 0,
+	XE_VSEC_BMG,
+};
+
+static struct intel_vsec_platform_info xe_vsec_info[] = {
+	[XE_VSEC_BMG] = {
+		.caps = VSEC_CAP_TELEMETRY | VSEC_CAP_CRASHLOG,
+		.headers = bmg_capabilities,
+	},
+	{ }
+};
+
+/*
+ * The GUID will have the following bits to decode:
+ *   [0:3]   - {Telemetry space iteration number (0,1,..)}
+ *   [4:7]   - Segment (SEGMENT_INDEPENDENT-0, Client-1, Server-2)
+ *   [8:11]  - SOC_SKU
+ *   [12:27] – Device ID – changes for each down bin SKU’s
+ *   [28:29] - Capability Type (Crashlog-0, Telemetry Aggregator-1, Watcher-2)
+ *   [30:31] - Record-ID (0-PUNIT, 1-OOBMSM_0, 2-OOBMSM_1)
+ */
+#define GUID_TELEM_ITERATION	GENMASK(3, 0)
+#define GUID_SEGMENT		GENMASK(7, 4)
+#define GUID_SOC_SKU		GENMASK(11, 8)
+#define GUID_DEVICE_ID		GENMASK(27, 12)
+#define GUID_CAP_TYPE		GENMASK(29, 28)
+#define GUID_RECORD_ID		GENMASK(31, 30)
+
+#define PUNIT_TELEMETRY_OFFSET		0x0200
+#define PUNIT_WATCHER_OFFSET		0x14A0
+#define OOBMSM_0_WATCHER_OFFSET		0x18D8
+#define OOBMSM_1_TELEMETRY_OFFSET	0x1000
+
+enum record_id {
+	PUNIT,
+	OOBMSM_0,
+	OOBMSM_1,
+};
+
+enum capability {
+	CRASHLOG,
+	TELEMETRY,
+	WATCHER,
+};
+
+static int guid_decode(u32 guid, int *index, u32 *offset)
+{
+	u32 record_id = FIELD_GET(GUID_RECORD_ID, guid);
+	u32 cap_type  = FIELD_GET(GUID_CAP_TYPE, guid);
+	u32 device_id = FIELD_GET(GUID_DEVICE_ID, guid);
+
+	if (device_id != BMG_DEVICE_ID)
+		return -ENODEV;
+
+	if (cap_type > WATCHER)
+		return -EINVAL;
+
+	*offset = 0;
+
+	if (cap_type == CRASHLOG) {
+		*index = record_id == PUNIT ? 2 : 4;
+		return 0;
+	}
+
+	switch (record_id) {
+	case PUNIT:
+		*index = 0;
+		if (cap_type == TELEMETRY)
+			*offset = PUNIT_TELEMETRY_OFFSET;
+		else
+			*offset = PUNIT_WATCHER_OFFSET;
+		break;
+
+	case OOBMSM_0:
+		*index = 1;
+		if (cap_type == WATCHER)
+			*offset = OOBMSM_0_WATCHER_OFFSET;
+		break;
+
+	case OOBMSM_1:
+		*index = 1;
+		if (cap_type == TELEMETRY)
+			*offset = OOBMSM_1_TELEMETRY_OFFSET;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int xe_pmt_telem_read(struct pci_dev *pdev, u32 guid, u64 *data, loff_t user_offset, u32 count)
+{
+	struct xe_device *xe = pdev_to_xe_device(pdev);
+	void __iomem *telem_addr = xe->mmio.regs + BMG_TELEMETRY_OFFSET;
+	u32 mem_region;
+	u32 offset;
+	int ret;
+
+	ret = guid_decode(guid, &mem_region, &offset);
+	if (ret)
+		return ret;
+
+	telem_addr += offset + user_offset;
+
+	guard(mutex)(&xe->pmt.lock);
+
+	/* indicate that we are not at an appropriate power level */
+	if (!xe_pm_runtime_get_if_active(xe))
+		return -ENODATA;
+
+	/* set SoC re-mapper index register based on GUID memory region */
+	xe_mmio_rmw32(xe_root_tile_mmio(xe), SG_REMAP_INDEX1, SG_REMAP_BITS,
+		      REG_FIELD_PREP(SG_REMAP_BITS, mem_region));
+
+	memcpy_fromio(data, telem_addr, count);
+	xe_pm_runtime_put(xe);
+
+	return count;
+}
+
+struct pmt_callbacks xe_pmt_cb = {
+	.read_telem = xe_pmt_telem_read,
+};
+
+static const int vsec_platforms[] = {
+	[XE_BATTLEMAGE] = XE_VSEC_BMG,
+};
+
+static enum xe_vsec get_platform_info(struct xe_device *xe)
+{
+	if (xe->info.platform > XE_BATTLEMAGE)
+		return XE_VSEC_UNKNOWN;
+
+	return vsec_platforms[xe->info.platform];
+}
+
+/**
+ * xe_vsec_init - Initialize resources and add intel_vsec auxiliary
+ * interface
+ * @xe: valid xe instance
+ */
+void xe_vsec_init(struct xe_device *xe)
+{
+	struct intel_vsec_platform_info *info;
+	struct device *dev = xe->drm.dev;
+	struct pci_dev *pdev = to_pci_dev(dev);
+	enum xe_vsec platform;
+
+	platform = get_platform_info(xe);
+	if (platform == XE_VSEC_UNKNOWN)
+		return;
+
+	info = &xe_vsec_info[platform];
+	if (!info->headers)
+		return;
+
+	switch (platform) {
+	case XE_VSEC_BMG:
+		info->priv_data = &xe_pmt_cb;
+		break;
+	default:
+		break;
+	}
+
+	/*
+	 * Register a VSEC. Cleanup is handled using device managed
+	 * resources.
+	 */
+	intel_vsec_register(pdev, info);
+}
+MODULE_IMPORT_NS(INTEL_VSEC);
diff --git a/drivers/gpu/drm/xe/xe_vsec.h b/drivers/gpu/drm/xe/xe_vsec.h
new file mode 100644
index 000000000000..7af2f1cf2bea
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_vsec.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#ifndef _XE_VSEC_H_
+#define _XE_VSEC_H_
+
+struct xe_device;
+
+void xe_vsec_init(struct xe_device *xe);
+
+#endif
-- 
2.44.0

Re: [PATCH 2/2] drm/xe/vsec: Support BMG devices

[Andy Shevchenko]

On Fri, Nov 08, 2024 at 03:19:54PM -0500, Michael J. Ruhl wrote:
> The Battlemage (BMG) discrete graphics card supports the
> Platform, Monitoring Technology (PMT) feature directly
> on the primary PCI device.
> 
> Utilize the PMT callback API to add support for the BMG
> devices.

...

> +	drmm_mutex_init(&xe->drm, &xe->pmt.lock);
> +

No error checks? What's the point of the (second) 'm' then?

...

> +/*
> + * Copyright © 2024 Intel Corporation
> + */

Can be one line.

> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/cleanup.h>

+ errno.h

> +#include <linux/intel_vsec.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/pci.h>

+ types.h

> +#include "xe_device.h"
> +#include "xe_device_types.h"
> +#include "xe_drv.h"
> +#include "xe_mmio.h"
> +#include "xe_platform_types.h"
> +#include "xe_pm.h"
> +#include "xe_vsec.h"

+ blank line?

> +#include "regs/xe_pmt.h"

...


I would add a comment here explaining that it's not a PCI ID,
while looking as that.

> +#define BMG_DEVICE_ID 0xE2F8

...

> +static int guid_decode(u32 guid, int *index, u32 *offset)

xe_guid_decode() to avoid any possible churn in the future due to namespace
collision.

...

> +++ b/drivers/gpu/drm/xe/xe_vsec.h


> +/*
> + * Copyright © 2024 Intel Corporation
> + */

One line?

-- 
With Best Regards,
Andy Shevchenko

RE: [PATCH 2/2] drm/xe/vsec: Support BMG devices

[Ruhl, Michael J]

> -----Original Message-----
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Sent: Monday, November 11, 2024 3:40 AM
> To: Ruhl, Michael J <michael.j.ruhl@intel.com>
> Cc: intel-xe@lists.freedesktop.org; platform-driver-x86@vger.kernel.org;
> david.e.box@linux.intel.com; ilpo.jarvinen@linux.intel.com;
> hdegoede@redhat.com; Vivi, Rodrigo <rodrigo.vivi@intel.com>; De Marchi,
> Lucas <lucas.demarchi@intel.com>
> Subject: Re: [PATCH 2/2] drm/xe/vsec: Support BMG devices
> 
> On Fri, Nov 08, 2024 at 03:19:54PM -0500, Michael J. Ruhl wrote:
> > The Battlemage (BMG) discrete graphics card supports the Platform,
> > Monitoring Technology (PMT) feature directly on the primary PCI
> > device.
> >
> > Utilize the PMT callback API to add support for the BMG devices.
> 
> ...
> 
> > +	drmm_mutex_init(&xe->drm, &xe->pmt.lock);
> > +
> 
> No error checks? What's the point of the (second) 'm' then?

Umm... not sure.  I will take a look.

 
> ...
> 
> > +/*
> > + * Copyright (c) 2024 Intel Corporation  */
> 
> Can be one line.
> 
> > +#include <linux/bitfield.h>
> > +#include <linux/bits.h>
> > +#include <linux/cleanup.h>
> 
> + errno.h
> 
> > +#include <linux/intel_vsec.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/pci.h>
> 
> + types.h
> 
> > +#include "xe_device.h"
> > +#include "xe_device_types.h"
> > +#include "xe_drv.h"
> > +#include "xe_mmio.h"
> > +#include "xe_platform_types.h"
> > +#include "xe_pm.h"
> > +#include "xe_vsec.h"
> 
> + blank line?
> 
> > +#include "regs/xe_pmt.h"
> 
> ...
> 
> 
> I would add a comment here explaining that it's not a PCI ID, while looking as
> that.

Very good point I will add a comment.

> > +#define BMG_DEVICE_ID 0xE2F8
> 
> ...
> 
> > +static int guid_decode(u32 guid, int *index, u32 *offset)
> 
> xe_guid_decode() to avoid any possible churn in the future due to namespace
> collision.

Will do.
 
> ...
> 
> > +++ b/drivers/gpu/drm/xe/xe_vsec.h
> 
> 
> > +/*
> > + * Copyright (c) 2024 Intel Corporation  */
> 
> One line?

Will do.

Thank you for your comments!.  Will get them addressed.

M

> --
> With Best Regards,
> Andy Shevchenko
> 

Re: [PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT callbacks

[Andy Shevchenko]

On Fri, Nov 08, 2024 at 03:19:53PM -0500, Michael J. Ruhl wrote:
> Usage of the telem sysfs file allows for partial reads at
> an offset.
> 
> The current callback method returns the buffer starting
> from offset 0 only.
> 
> Include the requested offset in the callback.
> Update the necsessary address calculations with the offset.

...

> -	memcpy_fromio(buf, addr, count);
> +	memcpy_fromio(buf, addr + off, count);

This will give an unaligned IO access in some cases. Is it a problem?

-- 
With Best Regards,
Andy Shevchenko

RE: [PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT callbacks

[Ruhl, Michael J]

> -----Original Message-----
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Sent: Monday, November 11, 2024 3:34 AM
> To: Ruhl, Michael J <michael.j.ruhl@intel.com>
> Cc: intel-xe@lists.freedesktop.org; platform-driver-x86@vger.kernel.org;
> david.e.box@linux.intel.com; ilpo.jarvinen@linux.intel.com;
> hdegoede@redhat.com; Vivi, Rodrigo <rodrigo.vivi@intel.com>; De Marchi,
> Lucas <lucas.demarchi@intel.com>
> Subject: Re: [PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT
> callbacks
> 
> On Fri, Nov 08, 2024 at 03:19:53PM -0500, Michael J. Ruhl wrote:
> > Usage of the telem sysfs file allows for partial reads at an offset.
> >
> > The current callback method returns the buffer starting from offset 0
> > only.
> >
> > Include the requested offset in the callback.
> > Update the necsessary address calculations with the offset.
> 
> ...
> 
> > -	memcpy_fromio(buf, addr, count);
> > +	memcpy_fromio(buf, addr + off, count);

Hi Andy,

> This will give an unaligned IO access in some cases. Is it a problem?

That is a good question.

I moved this value from the caller to this location.

So essentially it is "unchanged" from the current usage.  Does that answer
the question?

M
 
> --
> With Best Regards,
> Andy Shevchenko
> 

Re: [PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT callbacks

[Andy Shevchenko]

On Tue, Nov 12, 2024 at 02:38:06PM +0000, Ruhl, Michael J wrote:
> > -----Original Message-----
> > From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Sent: Monday, November 11, 2024 3:34 AM
> > To: Ruhl, Michael J <michael.j.ruhl@intel.com>
> > Cc: intel-xe@lists.freedesktop.org; platform-driver-x86@vger.kernel.org;
> > david.e.box@linux.intel.com; ilpo.jarvinen@linux.intel.com;
> > hdegoede@redhat.com; Vivi, Rodrigo <rodrigo.vivi@intel.com>; De Marchi,
> > Lucas <lucas.demarchi@intel.com>
> > Subject: Re: [PATCH 1/2] platform/x86/intel/pmt: allow user offset for PMT
> > callbacks
> > 
> > On Fri, Nov 08, 2024 at 03:19:53PM -0500, Michael J. Ruhl wrote:
> > > Usage of the telem sysfs file allows for partial reads at an offset.
> > >
> > > The current callback method returns the buffer starting from offset 0
> > > only.
> > >
> > > Include the requested offset in the callback.
> > > Update the necsessary address calculations with the offset.
> > 
> > ...
> > 
> > > -	memcpy_fromio(buf, addr, count);
> > > +	memcpy_fromio(buf, addr + off, count);
> 
> Hi Andy,
> 
> > This will give an unaligned IO access in some cases. Is it a problem?
> 
> That is a good question.
> 
> I moved this value from the caller to this location.
> 
> So essentially it is "unchanged" from the current usage.  Does that answer
> the question?

Probably. Please, mention this in the commit message.

-- 
With Best Regards,
Andy Shevchenko