@@ -515,7 +515,7 @@ If set, force use of the performance counters for oprofile, rather than detectin
available support.
### cpufreq
-> `= none | {{ <boolean> | xen } { [:[powersave|performance|ondemand|userspace][,[<maxfreq>]][,[<minfreq>]]] } [,verbose]} | dom0-kernel | hwp[:[<hdc>][,verbose]]`
+> `= none | {{ <boolean> | xen } { [:[powersave|performance|ondemand|userspace][,[<maxfreq>]][,[<minfreq>]]] } [,verbose]} | dom0-kernel | hwp[:[<hdc>][,verbose]] | amd-cppc[:[verbose]]`
> Default: `xen`
@@ -526,7 +526,7 @@ choice of `dom0-kernel` is deprecated and not supported by all Dom0 kernels.
* `<maxfreq>` and `<minfreq>` are integers which represent max and min processor frequencies
respectively.
* `verbose` option can be included as a string or also as `verbose=<integer>`
- for `xen`. It is a boolean for `hwp`.
+ for `xen`. It is a boolean for `hwp` and `amd-cppc`.
* `hwp` selects Hardware-Controlled Performance States (HWP) on supported Intel
hardware. HWP is a Skylake+ feature which provides better CPU power
management. The default is disabled. If `hwp` is selected, but hardware
@@ -534,6 +534,9 @@ choice of `dom0-kernel` is deprecated and not supported by all Dom0 kernels.
* `<hdc>` is a boolean to enable Hardware Duty Cycling (HDC). HDC enables the
processor to autonomously force physical package components into idle state.
The default is enabled, but the option only applies when `hwp` is enabled.
+* `amd-cppc` selects ACPI Collaborative Performance and Power Control (CPPC)
+ on supported AMD hardware to provide finer grained frequency control
+ mechanism. The default is disabled.
There is also support for `;`-separated fallback options:
`cpufreq=hwp;xen,verbose`. This first tries `hwp` and falls back to `xen` if
@@ -1,4 +1,5 @@
obj-$(CONFIG_INTEL) += acpi.o
+obj-$(CONFIG_AMD) += amd-cppc.o
obj-y += cpufreq.o
obj-$(CONFIG_INTEL) += hwp.o
obj-$(CONFIG_AMD) += powernow.o
@@ -13,6 +13,7 @@
#include <xen/errno.h>
#include <xen/delay.h>
+#include <xen/domain.h>
#include <xen/param.h>
#include <xen/types.h>
@@ -514,5 +515,16 @@ acpi_cpufreq_driver = {
int __init acpi_cpufreq_register(void)
{
- return cpufreq_register_driver(&acpi_cpufreq_driver);
+ int ret;
+
+ ret = cpufreq_register_driver(&acpi_cpufreq_driver);
+ if ( ret )
+ return ret;
+ /*
+ * After cpufreq driver registeration, XEN_PROCESSOR_PM_CPPC
+ * and XEN_PROCESSOR_PM_PX shall become exclusive flags
+ */
+ xen_processor_pmbits &= ~XEN_PROCESSOR_PM_CPPC;
+
+ return ret;
}
new file mode 100644
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * amd-cppc.c - AMD Processor CPPC Frequency Driver
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc. All Rights Reserved.
+ *
+ * Author: Penny Zheng <penny.zheng@amd.com>
+ *
+ * AMD CPPC cpufreq driver introduces a new CPU performance scaling design
+ * for AMD processors using the ACPI Collaborative Performance and Power
+ * Control (CPPC) feature which provides finer grained frequency control range.
+ */
+
+#include <xen/domain.h>
+#include <xen/init.h>
+#include <xen/param.h>
+#include <acpi/cpufreq/cpufreq.h>
+
+static bool __init amd_cppc_handle_option(const char *s, const char *end)
+{
+ int ret;
+
+ ret = parse_boolean("verbose", s, end);
+ if ( ret >= 0 )
+ {
+ cpufreq_verbose = ret;
+ return true;
+ }
+
+ return false;
+}
+
+int __init amd_cppc_cmdline_parse(const char *s, const char *e)
+{
+ do
+ {
+ const char *end = strpbrk(s, ",;");
+
+ if ( !amd_cppc_handle_option(s, end) )
+ {
+ printk(XENLOG_WARNING
+ "cpufreq/amd-cppc: option '%.*s' not recognized\n",
+ (int)((end ?: e) - s), s);
+
+ return -EINVAL;
+ }
+
+ s = end ? end + 1 : NULL;
+ } while ( s && s < e );
+
+ return 0;
+}
+
+static const struct cpufreq_driver __initconst_cf_clobber
+amd_cppc_cpufreq_driver =
+{
+ .name = XEN_AMD_CPPC_DRIVER_NAME,
+};
+
+int __init amd_cppc_register_driver(void)
+{
+ int ret;
+
+ if ( !cpu_has_cppc )
+ {
+ xen_processor_pmbits &= ~XEN_PROCESSOR_PM_CPPC;
+ return -ENODEV;
+ }
+
+ ret = cpufreq_register_driver(&amd_cppc_cpufreq_driver);
+ if ( ret )
+ return ret;
+
+ /*
+ * After cpufreq driver registeration, XEN_PROCESSOR_PM_CPPC
+ * and XEN_PROCESSOR_PM_PX shall become exclusive flags
+ */
+ xen_processor_pmbits &= ~XEN_PROCESSOR_PM_PX;
+
+ return ret;
+}
@@ -148,6 +148,10 @@ static int __init cf_check cpufreq_driver_init(void)
case CPUFREQ_none:
ret = 0;
break;
+ default:
+ printk(XENLOG_WARNING
+ "Unsupported cpufreq driver for vendor Intel\n");
+ break;
}
if ( ret != -ENODEV )
@@ -157,7 +161,35 @@ static int __init cf_check cpufreq_driver_init(void)
case X86_VENDOR_AMD:
case X86_VENDOR_HYGON:
- ret = IS_ENABLED(CONFIG_AMD) ? powernow_register_driver() : -ENODEV;
+ if ( !IS_ENABLED(CONFIG_AMD) )
+ {
+ ret = -ENODEV;
+ break;
+ }
+ ret = -ENOENT;
+
+ for ( unsigned int i = 0; i < cpufreq_xen_cnt; i++ )
+ {
+ switch ( cpufreq_xen_opts[i] )
+ {
+ case CPUFREQ_xen:
+ ret = powernow_register_driver();
+ break;
+ case CPUFREQ_amd_cppc:
+ ret = amd_cppc_register_driver();
+ break;
+ case CPUFREQ_none:
+ ret = 0;
+ break;
+ default:
+ printk(XENLOG_WARNING
+ "Unsupported cpufreq driver for vendor AMD or Hygon\n");
+ break;
+ }
+
+ if ( ret != -ENODEV )
+ break;
+ }
break;
}
}
@@ -542,6 +542,9 @@ ret_t do_platform_op(
ret = -ENOSYS;
break;
}
+ /* Xen doesn't support mixed mode */
+ ASSERT((xen_processor_pmbits & XEN_PROCESSOR_PM_CPPC) == 0);
+
ret = set_px_pminfo(op->u.set_pminfo.id, &op->u.set_pminfo.u.perf);
break;
@@ -573,6 +576,14 @@ ret_t do_platform_op(
}
case XEN_PM_CPPC:
+ if ( !(xen_processor_pmbits & XEN_PROCESSOR_PM_CPPC) )
+ {
+ ret = -EOPNOTSUPP;
+ break;
+ }
+ /* Xen doesn't support mixed mode */
+ ASSERT((xen_processor_pmbits & XEN_PROCESSOR_PM_PX) == 0);
+
ret = set_cppc_pminfo(op->u.set_pminfo.id,
&op->u.set_pminfo.u.cppc_data);
break;
@@ -65,7 +65,7 @@ LIST_HEAD_READ_MOSTLY(cpufreq_governor_list);
/* set xen as default cpufreq */
enum cpufreq_controller cpufreq_controller = FREQCTL_xen;
-enum cpufreq_xen_opt __initdata cpufreq_xen_opts[2] = { CPUFREQ_xen,
+enum cpufreq_xen_opt __initdata cpufreq_xen_opts[3] = { CPUFREQ_xen,
CPUFREQ_none };
unsigned int __initdata cpufreq_xen_cnt = 1;
@@ -90,7 +90,8 @@ static int __init handle_cpufreq_cmdline(enum cpufreq_xen_opt option)
if ( cpufreq_opts_contain(option) )
{
- const char *cpufreq_opts_str[] = { "CPUFREQ_xen", "CPUFREQ_hwp" };
+ const char *cpufreq_opts_str[] = { "CPUFREQ_xen", "CPUFREQ_hwp",
+ "CPUFREQ_amd_cppc" };
printk(XENLOG_WARNING
"Duplicate cpufreq driver option: %s",
@@ -102,6 +103,9 @@ static int __init handle_cpufreq_cmdline(enum cpufreq_xen_opt option)
cpufreq_xen_opts[cpufreq_xen_cnt++] = option;
switch ( option )
{
+ case CPUFREQ_amd_cppc:
+ xen_processor_pmbits |= XEN_PROCESSOR_PM_CPPC;
+ break;
case CPUFREQ_hwp:
case CPUFREQ_xen:
xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
@@ -168,6 +172,13 @@ static int __init cf_check setup_cpufreq_option(const char *str)
if ( arg[0] && arg[1] )
ret = hwp_cmdline_parse(arg + 1, end);
}
+ else if ( IS_ENABLED(CONFIG_AMD) && choice < 0 &&
+ !cmdline_strcmp(str, "amd-cppc") )
+ {
+ ret = handle_cpufreq_cmdline(CPUFREQ_amd_cppc);
+ if ( arg[0] && arg[1] )
+ ret = amd_cppc_cmdline_parse(arg + 1, end);
+ }
else
ret = -EINVAL;
@@ -28,8 +28,9 @@ enum cpufreq_xen_opt {
CPUFREQ_none,
CPUFREQ_xen,
CPUFREQ_hwp,
+ CPUFREQ_amd_cppc,
};
-extern enum cpufreq_xen_opt cpufreq_xen_opts[2];
+extern enum cpufreq_xen_opt cpufreq_xen_opts[3];
extern unsigned int cpufreq_xen_cnt;
struct cpufreq_governor;
@@ -277,4 +278,7 @@ int set_hwp_para(struct cpufreq_policy *policy,
int acpi_cpufreq_register(void);
+int amd_cppc_cmdline_parse(const char *s, const char *e);
+int amd_cppc_register_driver(void);
+
#endif /* __XEN_CPUFREQ_PM_H__ */
@@ -5,6 +5,9 @@
#include <public/sysctl.h>
#include <xen/acpi.h>
+/* ability bits */
+#define XEN_PROCESSOR_PM_CPPC 8
+
#define XEN_CPPC_INIT 0x40000000U
#define XEN_PX_INIT 0x80000000U
@@ -423,6 +423,7 @@ struct xen_set_cppc_para {
uint32_t activity_window;
};
+#define XEN_AMD_CPPC_DRIVER_NAME "amd-cppc"
#define XEN_HWP_DRIVER_NAME "hwp"
/*
Users need to set "cpufreq=amd-cppc" in xen cmdline to enable amd-cppc driver, which selects ACPI Collaborative Performance and Power Control (CPPC) on supported AMD hardware to provide a finer grained frequency control mechanism. `verbose` option can also be included to support verbose print. When users setting "cpufreq=amd-cppc", a new amd-cppc driver shall be registered and used. All hooks for amd-cppc driver are missing until commit "xen/x86: introduce a new amd cppc driver for cpufreq scaling" Xen is not expected to support both or mixed mode (CPPC & legacy PSS, _PCT, _PPC) operations, so only one cpufreq driver gets registerd, either amd-cppc or legacy P-states driver, which is reflected and asserted by the incompatible flags XEN_PROCESSOR_PM_PX and XEN_PROCESSOR_PM_CPPC. Signed-off-by: Penny Zheng <Penny.Zheng@amd.com> --- v1 -> v2: - Obey to alphabetic sorting and also strict it with CONFIG_AMD - Remove unnecessary empty comment line - Use __initconst_cf_clobber for pre-filled structure cpufreq_driver - Make new switch-case code apply to Hygon CPUs too - Change ENOSYS with EOPNOTSUPP - Blanks around binary operator - Change all amd_/-pstate defined values to amd_/-cppc --- v2 -> v3 - refactor too long lines - Make sure XEN_PROCESSOR_PM_PX and XEN_PROCESSOR_PM_CPPC incompatible flags after cpufreq register registrantion --- v3 -> v4: - introduce XEN_PROCESSOR_PM_CPPC in xen internal header - complement "Hygon" in log message - remove unnecessary if() - grow cpufreq_xen_opts[] array --- docs/misc/xen-command-line.pandoc | 7 +- xen/arch/x86/acpi/cpufreq/Makefile | 1 + xen/arch/x86/acpi/cpufreq/acpi.c | 14 +++- xen/arch/x86/acpi/cpufreq/amd-cppc.c | 81 +++++++++++++++++++++++ xen/arch/x86/acpi/cpufreq/cpufreq.c | 34 +++++++++- xen/arch/x86/platform_hypercall.c | 11 +++ xen/drivers/cpufreq/cpufreq.c | 15 ++++- xen/include/acpi/cpufreq/cpufreq.h | 6 +- xen/include/acpi/cpufreq/processor_perf.h | 3 + xen/include/public/sysctl.h | 1 + 10 files changed, 166 insertions(+), 7 deletions(-) create mode 100644 xen/arch/x86/acpi/cpufreq/amd-cppc.c