Re: [PATCH v3 1/2] platform/x86/amd: amd_3d_vcache: Add AMD 3D V-Cache optimizer driver

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On 10/22/2024 2:05 AM, Armin Wolf wrote:
Am 21.10.24 um 18:58 schrieb 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@xxxxxxx>
Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
Co-developed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@xxxxxxx>
---
  MAINTAINERS                           |   7 ++
  drivers/platform/x86/amd/Kconfig      |  12 ++
  drivers/platform/x86/amd/Makefile     |   2 +
  drivers/platform/x86/amd/x3d_vcache.c | 174 ++++++++++++++++++++++++++
  4 files changed, 195 insertions(+)
  create mode 100644 drivers/platform/x86/amd/x3d_vcache.c

diff --git a/MAINTAINERS b/MAINTAINERS
index e9659a5a7fb3..11b829956499 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@xxxxxxx>
+R:    Mario Limonciello <mario.limonciello@xxxxxxx>
+L:    platform-driver-x86@xxxxxxxxxxxxxxx
+S:    Supported
+F:    drivers/platform/x86/amd/x3d_vcache.c
+
  AMD ADDRESS TRANSLATION LIBRARY (ATL)
  M:    Yazen Ghannam <Yazen.Ghannam@xxxxxxx>
  L:    linux-edac@xxxxxxxxxxxxxxx
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..833e7704e6f9
--- /dev/null
+++ b/drivers/platform/x86/amd/x3d_vcache.c
@@ -0,0 +1,174 @@
+// 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@xxxxxxx>
+ *          Perry Yuan <perry.yuan@xxxxxxx>
+ *          Mario Limonciello <mario.limonciello@xxxxxxx>
+ *
+ */
+
+#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);
+
+    ret = amd_x3d_mode_switch(data, ret);
+    if (ret < 0)
+        return ret;
+
+    return 0;

Please directly return the result of amd_x3d_mode_switch() here.

Also i think that maybe there exists a way to avoid locking data->lock twice
during resume, but i will leave that to you.

I will leave as it is.

Other than that:

Reviewed-by: Armin Wolf <W_Armin@xxxxxx>

Thanks for the feedback. I will re-spin a new version after looking for more feedback from others. Thanks, -- Basavaraj


+}
+
+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");





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