[PATCH v4 0/2] Add support of AMD 3D V-Cache optimizer driver

[PATCH v4 0/2] Add support of AMD 3D V-Cache optimizer driver

[Basavaraj Natikar]

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AMD 3D V-Cache Technology significantly enhances per-core performance by
increasing the amount of L3 cache available—up to three times compared
to traditional architectures. This large cache allows for quicker access
to frequently used data, minimizing latency and boosting overall
efficiency in tasks that depend heavily on rapid data retrieval.

To fully leverage this technology, the AMD 3D V-Cache Optimizer has been
developed. This patch series introduces two distinct modes: Frequency
mode and Cache mode.

Frequency Mode: In this setting, the optimizer prioritizes boosting the
clock speed of the cores. This is particularly advantageous for
applications and workloads that benefit from higher clock frequencies,
enabling faster processing of tasks that are less reliant on cache size.

Cache Mode: Conversely, this mode focuses on maximizing the usage of the
expanded L3 cache. For workloads that are cache-sensitive—such as
certain gaming applications, data analytics, and other compute-intensive
processes—this mode allows the system to take full advantage of the
increased cache capacity, improving data throughput and reducing
bottlenecks.

Changes in v4:
	- Directly returned the result of function.

Changes in v3:
	- Changed the module parameter visibility to 0.
	- Removed the error log message.
	- Removed the error condition that will not be triggered.
	- Protected the data read case.
	- Moved the acpi_check_dsm check before allocation.
	- Added PM operations.

Changes in v2:
	- Used kfree() instead of ACPI_FREE(). 
	- Changed the ternary operator to an if statement.
	- Used acpi_check_dsm().
	- Used devm_mutex_init().
	- Removed acpi_match_device().
	- Removed the string format.

Basavaraj Natikar (2):
  platform/x86/amd: amd_3d_vcache: Add AMD 3D V-Cache optimizer driver
  platform/x86/amd: amd_3d_vcache: Add sysfs ABI documentation

 .../sysfs-bus-platform-drivers-amd_x3d_vcache |  12 ++
 MAINTAINERS                                   |   8 +
 drivers/platform/x86/amd/Kconfig              |  12 ++
 drivers/platform/x86/amd/Makefile             |   2 +
 drivers/platform/x86/amd/x3d_vcache.c         | 170 ++++++++++++++++++
 5 files changed, 204 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
 create mode 100644 drivers/platform/x86/amd/x3d_vcache.c

-- 
2.25.1

[PATCH v4 1/2] platform/x86/amd: amd_3d_vcache: Add AMD 3D V-Cache optimizer driver

[Basavaraj Natikar]

AMD X3D processors, also known as AMD 3D V-Cache, feature dual Core
Complex Dies (CCDs) and enlarged L3 cache, enabling dynamic mode
switching between Frequency and Cache modes. To optimize performance,
implement the AMD 3D V-Cache Optimizer, which allows selecting either:

Frequency mode: cores within the faster CCD are prioritized before
those in the slower CCD.

Cache mode: cores within the larger L3 CCD are prioritized before
those in the smaller L3 CCD.

Co-developed-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
---
 MAINTAINERS                           |   7 ++
 drivers/platform/x86/amd/Kconfig      |  12 ++
 drivers/platform/x86/amd/Makefile     |   2 +
 drivers/platform/x86/amd/x3d_vcache.c | 170 ++++++++++++++++++++++++++
 4 files changed, 191 insertions(+)
 create mode 100644 drivers/platform/x86/amd/x3d_vcache.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 91d0609db61b..60155effead9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -965,6 +965,13 @@ Q:	https://patchwork.kernel.org/project/linux-rdma/list/
 F:	drivers/infiniband/hw/efa/
 F:	include/uapi/rdma/efa-abi.h
 
+AMD 3D V-CACHE PERFORMANCE OPTIMIZER DRIVER
+M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
+R:	Mario Limonciello <mario.limonciello@amd.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Supported
+F:	drivers/platform/x86/amd/x3d_vcache.c
+
 AMD ADDRESS TRANSLATION LIBRARY (ATL)
 M:	Yazen Ghannam <Yazen.Ghannam@amd.com>
 L:	linux-edac@vger.kernel.org
diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
index f88682d36447..d73f691020d0 100644
--- a/drivers/platform/x86/amd/Kconfig
+++ b/drivers/platform/x86/amd/Kconfig
@@ -6,6 +6,18 @@
 source "drivers/platform/x86/amd/pmf/Kconfig"
 source "drivers/platform/x86/amd/pmc/Kconfig"
 
+config AMD_3D_VCACHE
+	tristate "AMD 3D V-Cache Performance Optimizer Driver"
+	depends on X86_64 && ACPI
+	help
+	  The driver provides a sysfs interface, enabling the setting of a bias
+	  that alters CPU core reordering. This bias prefers cores with higher
+	  frequencies or larger L3 caches on processors supporting AMD 3D V-Cache
+	  technology.
+
+	  If you choose to compile this driver as a module the module will be
+	  called amd_3d_vcache.
+
 config AMD_HSMP
 	tristate "AMD HSMP Driver"
 	depends on AMD_NB && X86_64 && ACPI
diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile
index dcec0a46f8af..16e4cce02242 100644
--- a/drivers/platform/x86/amd/Makefile
+++ b/drivers/platform/x86/amd/Makefile
@@ -4,6 +4,8 @@
 # AMD x86 Platform-Specific Drivers
 #
 
+obj-$(CONFIG_AMD_3D_VCACHE)     += amd_3d_vcache.o
+amd_3d_vcache-objs              := x3d_vcache.o
 obj-$(CONFIG_AMD_PMC)		+= pmc/
 amd_hsmp-y			:= hsmp.o
 obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
diff --git a/drivers/platform/x86/amd/x3d_vcache.c b/drivers/platform/x86/amd/x3d_vcache.c
new file mode 100644
index 000000000000..4a72ffe75cce
--- /dev/null
+++ b/drivers/platform/x86/amd/x3d_vcache.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AMD 3D V-Cache Performance Optimizer Driver
+ *
+ * Copyright (c) 2024, Advanced Micro Devices, Inc.
+ * All Rights Reserved.
+ *
+ * Authors: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
+ *          Perry Yuan <perry.yuan@amd.com>
+ *          Mario Limonciello <mario.limonciello@amd.com>
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+
+static char *x3d_mode = "frequency";
+module_param(x3d_mode, charp, 0);
+MODULE_PARM_DESC(x3d_mode, "Initial 3D-VCache mode; 'frequency' (default) or 'cache'");
+
+#define DSM_REVISION_ID			0
+#define DSM_SET_X3D_MODE		1
+
+static guid_t x3d_guid = GUID_INIT(0xdff8e55f, 0xbcfd, 0x46fb, 0xba, 0x0a,
+				   0xef, 0xd0, 0x45, 0x0f, 0x34, 0xee);
+
+enum amd_x3d_mode_type {
+	MODE_INDEX_FREQ,
+	MODE_INDEX_CACHE,
+};
+
+static const char * const amd_x3d_mode_strings[] = {
+	[MODE_INDEX_FREQ] = "frequency",
+	[MODE_INDEX_CACHE] = "cache",
+};
+
+struct amd_x3d_dev {
+	struct device *dev;
+	acpi_handle ahandle;
+	/* To protect x3d mode setting */
+	struct mutex lock;
+	enum amd_x3d_mode_type curr_mode;
+};
+
+static int amd_x3d_get_mode(struct amd_x3d_dev *data)
+{
+	guard(mutex)(&data->lock);
+
+	return data->curr_mode;
+}
+
+static int amd_x3d_mode_switch(struct amd_x3d_dev *data, int new_state)
+{
+	union acpi_object *out, argv;
+
+	guard(mutex)(&data->lock);
+	argv.type = ACPI_TYPE_INTEGER;
+	argv.integer.value = new_state;
+
+	out = acpi_evaluate_dsm(data->ahandle, &x3d_guid, DSM_REVISION_ID, DSM_SET_X3D_MODE,
+				&argv);
+	if (!out) {
+		dev_err(data->dev, "failed to evaluate _DSM\n");
+		return -EINVAL;
+	}
+
+	data->curr_mode = new_state;
+
+	kfree(out);
+
+	return 0;
+}
+
+static ssize_t amd_x3d_mode_store(struct device *dev, struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct amd_x3d_dev *data = dev_get_drvdata(dev);
+	int ret;
+
+	ret = sysfs_match_string(amd_x3d_mode_strings, buf);
+	if (ret < 0)
+		return ret;
+
+	ret = amd_x3d_mode_switch(data, ret);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t amd_x3d_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct amd_x3d_dev *data = dev_get_drvdata(dev);
+	int mode = amd_x3d_get_mode(data);
+
+	return sysfs_emit(buf, "%s\n", amd_x3d_mode_strings[mode]);
+}
+static DEVICE_ATTR_RW(amd_x3d_mode);
+
+static struct attribute *amd_x3d_attrs[] = {
+	&dev_attr_amd_x3d_mode.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(amd_x3d);
+
+static int amd_x3d_resume_handler(struct device *dev)
+{
+	struct amd_x3d_dev *data = dev_get_drvdata(dev);
+	int ret = amd_x3d_get_mode(data);
+
+	return amd_x3d_mode_switch(data, ret);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(amd_x3d_pm, NULL, amd_x3d_resume_handler);
+
+static const struct acpi_device_id amd_x3d_acpi_ids[] = {
+	{"AMDI0101"},
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, amd_x3d_acpi_ids);
+
+static int amd_x3d_probe(struct platform_device *pdev)
+{
+	struct amd_x3d_dev *data;
+	acpi_handle handle;
+	int ret;
+
+	handle = ACPI_HANDLE(&pdev->dev);
+	if (!handle)
+		return -ENODEV;
+
+	if (!acpi_check_dsm(handle, &x3d_guid, DSM_REVISION_ID, BIT(DSM_SET_X3D_MODE)))
+		return -ENODEV;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = &pdev->dev;
+	data->ahandle = handle;
+	platform_set_drvdata(pdev, data);
+
+	ret = match_string(amd_x3d_mode_strings, ARRAY_SIZE(amd_x3d_mode_strings), x3d_mode);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, -EINVAL, "invalid mode %s\n", x3d_mode);
+
+	devm_mutex_init(data->dev, &data->lock);
+
+	return amd_x3d_mode_switch(data, ret);
+}
+
+static struct platform_driver amd_3d_vcache_driver = {
+	.driver = {
+		.name = "amd_x3d_vcache",
+		.dev_groups = amd_x3d_groups,
+		.acpi_match_table = amd_x3d_acpi_ids,
+		.pm = pm_sleep_ptr(&amd_x3d_pm),
+	},
+	.probe = amd_x3d_probe,
+};
+module_platform_driver(amd_3d_vcache_driver);
+
+MODULE_DESCRIPTION("AMD 3D V-Cache Performance Optimizer Driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1

[PATCH v4 2/2] platform/x86/amd: amd_3d_vcache: Add sysfs ABI documentation

[Basavaraj Natikar]

Add documentation for the amd_3d_vcache sysfs bus platform driver
interface so that userspace applications can use it to change mode
preferences, either frequency or cache.

Co-developed-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
---
 .../sysfs-bus-platform-drivers-amd_x3d_vcache        | 12 ++++++++++++
 MAINTAINERS                                          |  1 +
 2 files changed, 13 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache

diff --git a/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache b/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
new file mode 100644
index 000000000000..5ff1f1a8c9b6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
@@ -0,0 +1,12 @@
+What:		/sys/bus/platform/drivers/amd_x3d_vcache/AMDI0101:00/amd_x3d_mode
+Date:           October 2024
+KernelVersion:	6.13
+Contact:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
+Description:	(RW) AMD 3D V-Cache optimizer allows users to switch CPU core
+		rankings dynamically.
+
+		This file switches between these two modes:
+		- "frequency" cores within the faster CCD are prioritized before
+		those in the slower CCD.
+		- "cache" cores within the larger L3 CCD are prioritized before
+		those in the smaller L3 CCD.
diff --git a/MAINTAINERS b/MAINTAINERS
index 60155effead9..5c29cdc6c1a4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -970,6 +970,7 @@ M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
 R:	Mario Limonciello <mario.limonciello@amd.com>
 L:	platform-driver-x86@vger.kernel.org
 S:	Supported
+F:	Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
 F:	drivers/platform/x86/amd/x3d_vcache.c
 
 AMD ADDRESS TRANSLATION LIBRARY (ATL)
-- 
2.25.1

Re: [PATCH v4 1/2] platform/x86/amd: amd_3d_vcache: Add AMD 3D V-Cache optimizer driver

[Ilpo Järvinen]

On Wed, 6 Nov 2024, Basavaraj Natikar wrote:

> AMD X3D processors, also known as AMD 3D V-Cache, feature dual Core
> Complex Dies (CCDs) and enlarged L3 cache, enabling dynamic mode
> switching between Frequency and Cache modes. To optimize performance,
> implement the AMD 3D V-Cache Optimizer, which allows selecting either:
> 
> Frequency mode: cores within the faster CCD are prioritized before
> those in the slower CCD.
> 
> Cache mode: cores within the larger L3 CCD are prioritized before
> those in the smaller L3 CCD.
> 
> Co-developed-by: Perry Yuan <perry.yuan@amd.com>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> ---
>  MAINTAINERS                           |   7 ++
>  drivers/platform/x86/amd/Kconfig      |  12 ++
>  drivers/platform/x86/amd/Makefile     |   2 +
>  drivers/platform/x86/amd/x3d_vcache.c | 170 ++++++++++++++++++++++++++
>  4 files changed, 191 insertions(+)
>  create mode 100644 drivers/platform/x86/amd/x3d_vcache.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 91d0609db61b..60155effead9 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -965,6 +965,13 @@ Q:	https://patchwork.kernel.org/project/linux-rdma/list/
>  F:	drivers/infiniband/hw/efa/
>  F:	include/uapi/rdma/efa-abi.h
>  
> +AMD 3D V-CACHE PERFORMANCE OPTIMIZER DRIVER
> +M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> +R:	Mario Limonciello <mario.limonciello@amd.com>
> +L:	platform-driver-x86@vger.kernel.org
> +S:	Supported
> +F:	drivers/platform/x86/amd/x3d_vcache.c
> +
>  AMD ADDRESS TRANSLATION LIBRARY (ATL)
>  M:	Yazen Ghannam <Yazen.Ghannam@amd.com>
>  L:	linux-edac@vger.kernel.org
> diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
> index f88682d36447..d73f691020d0 100644
> --- a/drivers/platform/x86/amd/Kconfig
> +++ b/drivers/platform/x86/amd/Kconfig
> @@ -6,6 +6,18 @@
>  source "drivers/platform/x86/amd/pmf/Kconfig"
>  source "drivers/platform/x86/amd/pmc/Kconfig"
>  
> +config AMD_3D_VCACHE
> +	tristate "AMD 3D V-Cache Performance Optimizer Driver"
> +	depends on X86_64 && ACPI
> +	help
> +	  The driver provides a sysfs interface, enabling the setting of a bias
> +	  that alters CPU core reordering. This bias prefers cores with higher
> +	  frequencies or larger L3 caches on processors supporting AMD 3D V-Cache
> +	  technology.
> +
> +	  If you choose to compile this driver as a module the module will be
> +	  called amd_3d_vcache.
> +
>  config AMD_HSMP
>  	tristate "AMD HSMP Driver"
>  	depends on AMD_NB && X86_64 && ACPI
> diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile
> index dcec0a46f8af..16e4cce02242 100644
> --- a/drivers/platform/x86/amd/Makefile
> +++ b/drivers/platform/x86/amd/Makefile
> @@ -4,6 +4,8 @@
>  # AMD x86 Platform-Specific Drivers
>  #
>  
> +obj-$(CONFIG_AMD_3D_VCACHE)     += amd_3d_vcache.o
> +amd_3d_vcache-objs              := x3d_vcache.o
>  obj-$(CONFIG_AMD_PMC)		+= pmc/
>  amd_hsmp-y			:= hsmp.o
>  obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
> diff --git a/drivers/platform/x86/amd/x3d_vcache.c b/drivers/platform/x86/amd/x3d_vcache.c
> new file mode 100644
> index 000000000000..4a72ffe75cce
> --- /dev/null
> +++ b/drivers/platform/x86/amd/x3d_vcache.c
> @@ -0,0 +1,170 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * AMD 3D V-Cache Performance Optimizer Driver
> + *
> + * Copyright (c) 2024, Advanced Micro Devices, Inc.
> + * All Rights Reserved.

Are you sure you need the "All Rights Reserved." part? While I'm not a 
lawyer, GPL only reserves some rights AFAICT.

> + *
> + * Authors: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> + *          Perry Yuan <perry.yuan@amd.com>
> + *          Mario Limonciello <mario.limonciello@amd.com>
> + *

Extra line.

> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +
> +static char *x3d_mode = "frequency";
> +module_param(x3d_mode, charp, 0);
> +MODULE_PARM_DESC(x3d_mode, "Initial 3D-VCache mode; 'frequency' (default) or 'cache'");
> +
> +#define DSM_REVISION_ID			0
> +#define DSM_SET_X3D_MODE		1
> +
> +static guid_t x3d_guid = GUID_INIT(0xdff8e55f, 0xbcfd, 0x46fb, 0xba, 0x0a,
> +				   0xef, 0xd0, 0x45, 0x0f, 0x34, 0xee);

Missing include.

> +enum amd_x3d_mode_type {
> +	MODE_INDEX_FREQ,
> +	MODE_INDEX_CACHE,
> +};
> +
> +static const char * const amd_x3d_mode_strings[] = {
> +	[MODE_INDEX_FREQ] = "frequency",
> +	[MODE_INDEX_CACHE] = "cache",
> +};
> +
> +struct amd_x3d_dev {
> +	struct device *dev;
> +	acpi_handle ahandle;
> +	/* To protect x3d mode setting */
> +	struct mutex lock;
> +	enum amd_x3d_mode_type curr_mode;
> +};
> +
> +static int amd_x3d_get_mode(struct amd_x3d_dev *data)
> +{
> +	guard(mutex)(&data->lock);
> +
> +	return data->curr_mode;

Are you aware that the mutex doesn't really do much here, as soon as it's 
released, the value can change again?

> +}
> +
> +static int amd_x3d_mode_switch(struct amd_x3d_dev *data, int new_state)
> +{
> +	union acpi_object *out, argv;
> +
> +	guard(mutex)(&data->lock);
> +	argv.type = ACPI_TYPE_INTEGER;
> +	argv.integer.value = new_state;
> +
> +	out = acpi_evaluate_dsm(data->ahandle, &x3d_guid, DSM_REVISION_ID, DSM_SET_X3D_MODE,
> +				&argv);

Since you need to split the line anyway, I'd move the second DSM to the 
second line.

> +	if (!out) {
> +		dev_err(data->dev, "failed to evaluate _DSM\n");
> +		return -EINVAL;
> +	}
> +
> +	data->curr_mode = new_state;
> +
> +	kfree(out);
> +
> +	return 0;
> +}
> +
> +static ssize_t amd_x3d_mode_store(struct device *dev, struct device_attribute *attr,
> +				  const char *buf, size_t count)
> +{
> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = sysfs_match_string(amd_x3d_mode_strings, buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = amd_x3d_mode_switch(data, ret);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t amd_x3d_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
> +	int mode = amd_x3d_get_mode(data);
> +
> +	return sysfs_emit(buf, "%s\n", amd_x3d_mode_strings[mode]);
> +}
> +static DEVICE_ATTR_RW(amd_x3d_mode);
> +
> +static struct attribute *amd_x3d_attrs[] = {
> +	&dev_attr_amd_x3d_mode.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(amd_x3d);

Add #include.

> +
> +static int amd_x3d_resume_handler(struct device *dev)
> +{
> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
> +	int ret = amd_x3d_get_mode(data);
> +
> +	return amd_x3d_mode_switch(data, ret);
> +}
> +
> +static DEFINE_SIMPLE_DEV_PM_OPS(amd_x3d_pm, NULL, amd_x3d_resume_handler);

Add include.

> +
> +static const struct acpi_device_id amd_x3d_acpi_ids[] = {
> +	{"AMDI0101"},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, amd_x3d_acpi_ids);
> +
> +static int amd_x3d_probe(struct platform_device *pdev)
> +{
> +	struct amd_x3d_dev *data;
> +	acpi_handle handle;
> +	int ret;
> +
> +	handle = ACPI_HANDLE(&pdev->dev);
> +	if (!handle)
> +		return -ENODEV;
> +
> +	if (!acpi_check_dsm(handle, &x3d_guid, DSM_REVISION_ID, BIT(DSM_SET_X3D_MODE)))
> +		return -ENODEV;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->dev = &pdev->dev;
> +	data->ahandle = handle;
> +	platform_set_drvdata(pdev, data);
> +
> +	ret = match_string(amd_x3d_mode_strings, ARRAY_SIZE(amd_x3d_mode_strings), x3d_mode);

Add include for ARRAY_SIZE()

> +	if (ret < 0)
> +		return dev_err_probe(&pdev->dev, -EINVAL, "invalid mode %s\n", x3d_mode);
> +
> +	devm_mutex_init(data->dev, &data->lock);
> +
> +	return amd_x3d_mode_switch(data, ret);
> +}
> +
> +static struct platform_driver amd_3d_vcache_driver = {
> +	.driver = {
> +		.name = "amd_x3d_vcache",
> +		.dev_groups = amd_x3d_groups,
> +		.acpi_match_table = amd_x3d_acpi_ids,
> +		.pm = pm_sleep_ptr(&amd_x3d_pm),
> +	},
> +	.probe = amd_x3d_probe,
> +};
> +module_platform_driver(amd_3d_vcache_driver);
> +
> +MODULE_DESCRIPTION("AMD 3D V-Cache Performance Optimizer Driver");
> +MODULE_LICENSE("GPL");
> 

-- 
 i.

Re: [PATCH v4 2/2] platform/x86/amd: amd_3d_vcache: Add sysfs ABI documentation

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2404 bytes --]

On Wed, 6 Nov 2024, Basavaraj Natikar wrote:

> Add documentation for the amd_3d_vcache sysfs bus platform driver
> interface so that userspace applications can use it to change mode
> preferences, either frequency or cache.
> 
> Co-developed-by: Perry Yuan <perry.yuan@amd.com>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> ---
>  .../sysfs-bus-platform-drivers-amd_x3d_vcache        | 12 ++++++++++++
>  MAINTAINERS                                          |  1 +
>  2 files changed, 13 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache b/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
> new file mode 100644
> index 000000000000..5ff1f1a8c9b6
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
> @@ -0,0 +1,12 @@
> +What:		/sys/bus/platform/drivers/amd_x3d_vcache/AMDI0101:00/amd_x3d_mode
> +Date:           October 2024

Space -> tabs.

With that addressed,

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

> +KernelVersion:	6.13
> +Contact:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> +Description:	(RW) AMD 3D V-Cache optimizer allows users to switch CPU core
> +		rankings dynamically.
> +
> +		This file switches between these two modes:
> +		- "frequency" cores within the faster CCD are prioritized before
> +		those in the slower CCD.
> +		- "cache" cores within the larger L3 CCD are prioritized before
> +		those in the smaller L3 CCD.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 60155effead9..5c29cdc6c1a4 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -970,6 +970,7 @@ M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>  R:	Mario Limonciello <mario.limonciello@amd.com>
>  L:	platform-driver-x86@vger.kernel.org
>  S:	Supported
> +F:	Documentation/ABI/testing/sysfs-bus-platform-drivers-amd_x3d_vcache
>  F:	drivers/platform/x86/amd/x3d_vcache.c
>  
>  AMD ADDRESS TRANSLATION LIBRARY (ATL)
> 

-- 
 i.

Re: [PATCH v4 1/2] platform/x86/amd: amd_3d_vcache: Add AMD 3D V-Cache optimizer driver

[Basavaraj Natikar]

On 11/6/2024 7:17 PM, Ilpo Järvinen wrote:
> On Wed, 6 Nov 2024, Basavaraj Natikar wrote:
>
>> AMD X3D processors, also known as AMD 3D V-Cache, feature dual Core
>> Complex Dies (CCDs) and enlarged L3 cache, enabling dynamic mode
>> switching between Frequency and Cache modes. To optimize performance,
>> implement the AMD 3D V-Cache Optimizer, which allows selecting either:
>>
>> Frequency mode: cores within the faster CCD are prioritized before
>> those in the slower CCD.
>>
>> Cache mode: cores within the larger L3 CCD are prioritized before
>> those in the smaller L3 CCD.
>>
>> Co-developed-by: Perry Yuan <perry.yuan@amd.com>
>> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
>> Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
>> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
>> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>> ---
>>   MAINTAINERS                           |   7 ++
>>   drivers/platform/x86/amd/Kconfig      |  12 ++
>>   drivers/platform/x86/amd/Makefile     |   2 +
>>   drivers/platform/x86/amd/x3d_vcache.c | 170 ++++++++++++++++++++++++++
>>   4 files changed, 191 insertions(+)
>>   create mode 100644 drivers/platform/x86/amd/x3d_vcache.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 91d0609db61b..60155effead9 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -965,6 +965,13 @@ Q:	https://patchwork.kernel.org/project/linux-rdma/list/
>>   F:	drivers/infiniband/hw/efa/
>>   F:	include/uapi/rdma/efa-abi.h
>>   
>> +AMD 3D V-CACHE PERFORMANCE OPTIMIZER DRIVER
>> +M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>> +R:	Mario Limonciello <mario.limonciello@amd.com>
>> +L:	platform-driver-x86@vger.kernel.org
>> +S:	Supported
>> +F:	drivers/platform/x86/amd/x3d_vcache.c
>> +
>>   AMD ADDRESS TRANSLATION LIBRARY (ATL)
>>   M:	Yazen Ghannam <Yazen.Ghannam@amd.com>
>>   L:	linux-edac@vger.kernel.org
>> diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
>> index f88682d36447..d73f691020d0 100644
>> --- a/drivers/platform/x86/amd/Kconfig
>> +++ b/drivers/platform/x86/amd/Kconfig
>> @@ -6,6 +6,18 @@
>>   source "drivers/platform/x86/amd/pmf/Kconfig"
>>   source "drivers/platform/x86/amd/pmc/Kconfig"
>>   
>> +config AMD_3D_VCACHE
>> +	tristate "AMD 3D V-Cache Performance Optimizer Driver"
>> +	depends on X86_64 && ACPI
>> +	help
>> +	  The driver provides a sysfs interface, enabling the setting of a bias
>> +	  that alters CPU core reordering. This bias prefers cores with higher
>> +	  frequencies or larger L3 caches on processors supporting AMD 3D V-Cache
>> +	  technology.
>> +
>> +	  If you choose to compile this driver as a module the module will be
>> +	  called amd_3d_vcache.
>> +
>>   config AMD_HSMP
>>   	tristate "AMD HSMP Driver"
>>   	depends on AMD_NB && X86_64 && ACPI
>> diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile
>> index dcec0a46f8af..16e4cce02242 100644
>> --- a/drivers/platform/x86/amd/Makefile
>> +++ b/drivers/platform/x86/amd/Makefile
>> @@ -4,6 +4,8 @@
>>   # AMD x86 Platform-Specific Drivers
>>   #
>>   
>> +obj-$(CONFIG_AMD_3D_VCACHE)     += amd_3d_vcache.o
>> +amd_3d_vcache-objs              := x3d_vcache.o
>>   obj-$(CONFIG_AMD_PMC)		+= pmc/
>>   amd_hsmp-y			:= hsmp.o
>>   obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
>> diff --git a/drivers/platform/x86/amd/x3d_vcache.c b/drivers/platform/x86/amd/x3d_vcache.c
>> new file mode 100644
>> index 000000000000..4a72ffe75cce
>> --- /dev/null
>> +++ b/drivers/platform/x86/amd/x3d_vcache.c
>> @@ -0,0 +1,170 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * AMD 3D V-Cache Performance Optimizer Driver
>> + *
>> + * Copyright (c) 2024, Advanced Micro Devices, Inc.
>> + * All Rights Reserved.
> Are you sure you need the "All Rights Reserved." part? While I'm not a
> lawyer, GPL only reserves some rights AFAICT.

yes this is correct.

>
>> + *
>> + * Authors: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>> + *          Perry Yuan <perry.yuan@amd.com>
>> + *          Mario Limonciello <mario.limonciello@amd.com>
>> + *
> Extra line.
>
>> + */
>> +
>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/device.h>
>> +#include <linux/errno.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/platform_device.h>
>> +
>> +static char *x3d_mode = "frequency";
>> +module_param(x3d_mode, charp, 0);
>> +MODULE_PARM_DESC(x3d_mode, "Initial 3D-VCache mode; 'frequency' (default) or 'cache'");
>> +
>> +#define DSM_REVISION_ID			0
>> +#define DSM_SET_X3D_MODE		1
>> +
>> +static guid_t x3d_guid = GUID_INIT(0xdff8e55f, 0xbcfd, 0x46fb, 0xba, 0x0a,
>> +				   0xef, 0xd0, 0x45, 0x0f, 0x34, 0xee);
> Missing include.
>
>> +enum amd_x3d_mode_type {
>> +	MODE_INDEX_FREQ,
>> +	MODE_INDEX_CACHE,
>> +};
>> +
>> +static const char * const amd_x3d_mode_strings[] = {
>> +	[MODE_INDEX_FREQ] = "frequency",
>> +	[MODE_INDEX_CACHE] = "cache",
>> +};
>> +
>> +struct amd_x3d_dev {
>> +	struct device *dev;
>> +	acpi_handle ahandle;
>> +	/* To protect x3d mode setting */
>> +	struct mutex lock;
>> +	enum amd_x3d_mode_type curr_mode;
>> +};
>> +
>> +static int amd_x3d_get_mode(struct amd_x3d_dev *data)
>> +{
>> +	guard(mutex)(&data->lock);
>> +
>> +	return data->curr_mode;
> Are you aware that the mutex doesn't really do much here, as soon as it's
> released, the value can change again?

Yes, that's correct; the value can change again. At least it uses the latest
one, while simultaneous writing is ongoing.

Thanks,
--
Basavaraj

>
>> +}
>> +
>> +static int amd_x3d_mode_switch(struct amd_x3d_dev *data, int new_state)
>> +{
>> +	union acpi_object *out, argv;
>> +
>> +	guard(mutex)(&data->lock);
>> +	argv.type = ACPI_TYPE_INTEGER;
>> +	argv.integer.value = new_state;
>> +
>> +	out = acpi_evaluate_dsm(data->ahandle, &x3d_guid, DSM_REVISION_ID, DSM_SET_X3D_MODE,
>> +				&argv);
> Since you need to split the line anyway, I'd move the second DSM to the
> second line.
>
>> +	if (!out) {
>> +		dev_err(data->dev, "failed to evaluate _DSM\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	data->curr_mode = new_state;
>> +
>> +	kfree(out);
>> +
>> +	return 0;
>> +}
>> +
>> +static ssize_t amd_x3d_mode_store(struct device *dev, struct device_attribute *attr,
>> +				  const char *buf, size_t count)
>> +{
>> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = sysfs_match_string(amd_x3d_mode_strings, buf);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = amd_x3d_mode_switch(data, ret);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return count;
>> +}
>> +
>> +static ssize_t amd_x3d_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
>> +{
>> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
>> +	int mode = amd_x3d_get_mode(data);
>> +
>> +	return sysfs_emit(buf, "%s\n", amd_x3d_mode_strings[mode]);
>> +}
>> +static DEVICE_ATTR_RW(amd_x3d_mode);
>> +
>> +static struct attribute *amd_x3d_attrs[] = {
>> +	&dev_attr_amd_x3d_mode.attr,
>> +	NULL
>> +};
>> +ATTRIBUTE_GROUPS(amd_x3d);
> Add #include.
>
>> +
>> +static int amd_x3d_resume_handler(struct device *dev)
>> +{
>> +	struct amd_x3d_dev *data = dev_get_drvdata(dev);
>> +	int ret = amd_x3d_get_mode(data);
>> +
>> +	return amd_x3d_mode_switch(data, ret);
>> +}
>> +
>> +static DEFINE_SIMPLE_DEV_PM_OPS(amd_x3d_pm, NULL, amd_x3d_resume_handler);
> Add include.
>
>> +
>> +static const struct acpi_device_id amd_x3d_acpi_ids[] = {
>> +	{"AMDI0101"},
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(acpi, amd_x3d_acpi_ids);
>> +
>> +static int amd_x3d_probe(struct platform_device *pdev)
>> +{
>> +	struct amd_x3d_dev *data;
>> +	acpi_handle handle;
>> +	int ret;
>> +
>> +	handle = ACPI_HANDLE(&pdev->dev);
>> +	if (!handle)
>> +		return -ENODEV;
>> +
>> +	if (!acpi_check_dsm(handle, &x3d_guid, DSM_REVISION_ID, BIT(DSM_SET_X3D_MODE)))
>> +		return -ENODEV;
>> +
>> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	data->dev = &pdev->dev;
>> +	data->ahandle = handle;
>> +	platform_set_drvdata(pdev, data);
>> +
>> +	ret = match_string(amd_x3d_mode_strings, ARRAY_SIZE(amd_x3d_mode_strings), x3d_mode);
> Add include for ARRAY_SIZE()
>
>> +	if (ret < 0)
>> +		return dev_err_probe(&pdev->dev, -EINVAL, "invalid mode %s\n", x3d_mode);
>> +
>> +	devm_mutex_init(data->dev, &data->lock);
>> +
>> +	return amd_x3d_mode_switch(data, ret);
>> +}
>> +
>> +static struct platform_driver amd_3d_vcache_driver = {
>> +	.driver = {
>> +		.name = "amd_x3d_vcache",
>> +		.dev_groups = amd_x3d_groups,
>> +		.acpi_match_table = amd_x3d_acpi_ids,
>> +		.pm = pm_sleep_ptr(&amd_x3d_pm),
>> +	},
>> +	.probe = amd_x3d_probe,
>> +};
>> +module_platform_driver(amd_3d_vcache_driver);
>> +
>> +MODULE_DESCRIPTION("AMD 3D V-Cache Performance Optimizer Driver");
>> +MODULE_LICENSE("GPL");
>>