qubes-linux-kernel/patches.xen/pvops-0010-CPUFREQ-xen-governor-for-Xen-hypervisor-frequency-sc.patch

From 20e7a07fa0f8a0dbe30a0f732686d78849d29d96 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Fri, 3 Feb 2012 16:03:20 -0500
Subject: [CPUFREQ] xen: governor for Xen hypervisor frequency scaling.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This CPU freq governor leaves the frequency decision to the Xen hypervisor.

To do that the driver parses the Power Management data and uploads said
information to the Xen hypervisor. Then the Xen hypervisor can select the
proper Cx and Pxx states for the initial domain and all other domains.

To upload the information, this CPU frequency driver reads Power Management (PM)
(_Pxx and _Cx) which are populated in the 'struct acpi_processor' structure.
It simply reads the contents of that structure and pass it up the Xen hypervisor.
For that to work we depend on the appropriate CPU frequency scaling driver
to do the heavy-lifting - so that the contents is correct.

The CPU frequency governor it has been loaded also sets up a timer
to check if the ACPI IDs count is different from the APIC ID count - which
can happen if the user choose to use dom0_max_vcpu argument. In such a case
a backup of the PM structure is used and uploaded to the hypervisor.

[v1-v2: Initial RFC implementations that were posted]
[v3: Changed the name to passthru suggested by Pasi Kärkkäinen <pasik@iki.fi>]
[v4: Added vCPU != pCPU support - aka dom0_max_vcpus support]
[v5: Cleaned up the driver, fix bug under Athlon XP]
[v6: Changed the driver to a CPU frequency governor]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/Kconfig       |   15 ++
 drivers/xen/Makefile      |    2 +-
 drivers/xen/cpufreq_xen.c |  445 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 461 insertions(+), 1 deletions(-)
 create mode 100644 drivers/xen/cpufreq_xen.c

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index a1ced52..28ba371 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -178,4 +178,19 @@ config XEN_PRIVCMD
 	depends on XEN
 	default m
 
+config CPU_FREQ_GOV_XEN
+	tristate "'xen' governor for hypervisor scaling"
+	depends on XEN && X86 && ACPI_PROCESSOR && CPU_FREQ
+	default m
+	help
+          This cpufreq governor leaves the frequency decision to the Xen hypervisor.
+
+	  To do that the driver parses the Power Management data and uploads said
+	  information to the Xen hypervisor. Then the Xen hypervisor can select the
+          proper Cx and Pxx states.
+
+          To compile this driver as a module, choose M here: the
+          module will be called cpufreq_xen.  If you do not know what to choose,
+          select M here.
+
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index aa31337..5802220 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -20,7 +20,7 @@ obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
 obj-$(CONFIG_XEN_DOM0)			+= pci.o acpi.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)		+= xen-privcmd.o
-
+obj-$(CONFIG_CPU_FREQ_GOV_XEN)		+= cpufreq_xen.o
 xen-evtchn-y				:= evtchn.o
 xen-gntdev-y				:= gntdev.o
 xen-gntalloc-y				:= gntalloc.o
diff --git a/drivers/xen/cpufreq_xen.c b/drivers/xen/cpufreq_xen.c
new file mode 100644
index 0000000..1b709bf
--- /dev/null
+++ b/drivers/xen/cpufreq_xen.c
@@ -0,0 +1,445 @@
+/*
+ * Copyright 2012 by Oracle Inc
+ * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+ *
+ * This code borrows ideas from https://lkml.org/lkml/2011/11/30/249
+ * so many thanks go to Kevin Tian <kevin.tian@intel.com>
+ * and Yu Ke <ke.yu@intel.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/cpumask.h>
+#include <linux/cpufreq.h>
+#include <linux/freezer.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+#include <acpi/processor.h>
+
+#include <xen/interface/platform.h>
+#include <asm/xen/hypercall.h>
+
+#define DRV_NAME "cpufreq-xen"
+
+static int no_hypercall;
+MODULE_PARM_DESC(off, "Inhibit the hypercall.");
+module_param_named(off, no_hypercall, int, 0400);
+
+/*
+ * Mutex to protect the acpi_ids_done.
+ */
+static DEFINE_MUTEX(acpi_ids_mutex);
+/*
+ * Don't think convert this to cpumask_var_t or use cpumask_bit - as those
+ * shrink to nr_cpu_bits (which is dependent on possible_cpu), which can be
+ * less than what we want to put in.
+ */
+#define NR_ACPI_CPUS	NR_CPUS
+#define MAX_ACPI_BITS	(BITS_TO_LONGS(NR_ACPI_CPUS))
+static unsigned long *acpi_ids_done;
+/*
+ * Again, don't convert to cpumask - as we are reading the raw ACPI CPU ids
+ * which can go beyond what we presently see.
+ */
+static unsigned long *acpi_id_present;
+
+/*
+ * Pertient data for the timer to be launched to check if the # of
+ * ACPI CPU ids is different from the one we have processed.
+ */
+#define DELAY_TIMER	msecs_to_jiffies(5000 /* 5 sec */)
+static struct acpi_processor *pr_backup;
+static struct delayed_work work;
+
+static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
+{
+	struct xen_platform_op op = {
+		.cmd			= XENPF_set_processor_pminfo,
+		.interface_version	= XENPF_INTERFACE_VERSION,
+		.u.set_pminfo.id	= _pr->acpi_id,
+		.u.set_pminfo.type	= XEN_PM_CX,
+	};
+	struct xen_processor_cx *dst_cx, *dst_cx_states = NULL;
+	struct acpi_processor_cx *cx;
+	int i, ok, ret = 0;
+
+	dst_cx_states = kcalloc(_pr->power.count,
+				sizeof(struct xen_processor_cx), GFP_KERNEL);
+	if (!dst_cx_states)
+		return -ENOMEM;
+
+	for (ok = 0, i = 1; i <= _pr->power.count; i++) {
+		cx = &_pr->power.states[i];
+		if (!cx->valid)
+			continue;
+
+		dst_cx = &(dst_cx_states[ok++]);
+
+		dst_cx->reg.space_id = ACPI_ADR_SPACE_SYSTEM_IO;
+		if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
+			dst_cx->reg.bit_width = 8;
+			dst_cx->reg.bit_offset = 0;
+			dst_cx->reg.access_size = 1;
+		} else {
+			dst_cx->reg.space_id = ACPI_ADR_SPACE_FIXED_HARDWARE;
+			if (cx->entry_method == ACPI_CSTATE_FFH) {
+				/* NATIVE_CSTATE_BEYOND_HALT */
+				dst_cx->reg.bit_offset = 2;
+				dst_cx->reg.bit_width = 1; /* VENDOR_INTEL */
+			}
+			dst_cx->reg.access_size = 0;
+		}
+		dst_cx->reg.address = cx->address;
+
+		dst_cx->type = cx->type;
+		dst_cx->latency = cx->latency;
+		dst_cx->power = cx->power;
+
+		dst_cx->dpcnt = 0;
+		set_xen_guest_handle(dst_cx->dp, NULL);
+#ifdef DEBUG
+		pr_debug(DRV_NAME ": CX: ID:%d [C%d:%s] entry:%d\n",
+			_pr->acpi_id, cx->type, cx->desc, cx->entry_method);
+#endif
+	}
+	if (!ok) {
+		pr_err(DRV_NAME ": No _Cx for CPU %d\n", _pr->acpi_id);
+		kfree(dst_cx_states);
+		return -EINVAL;
+	}
+	op.u.set_pminfo.power.count = ok;
+	op.u.set_pminfo.power.flags.bm_control = _pr->flags.bm_control;
+	op.u.set_pminfo.power.flags.bm_check = _pr->flags.bm_check;
+	op.u.set_pminfo.power.flags.has_cst = _pr->flags.has_cst;
+	op.u.set_pminfo.power.flags.power_setup_done =
+		_pr->flags.power_setup_done;
+
+	set_xen_guest_handle(op.u.set_pminfo.power.states, dst_cx_states);
+
+	if (!no_hypercall)
+		ret = HYPERVISOR_dom0_op(&op);
+
+	if (ret)
+		pr_err(DRV_NAME "(CX): Hypervisor error (%d) for ACPI ID: %d\n",
+		       ret, _pr->acpi_id);
+
+	kfree(dst_cx_states);
+
+	return ret;
+}
+static struct xen_processor_px *
+xen_copy_pss_data(struct acpi_processor *_pr,
+		  struct xen_processor_performance *dst_perf)
+{
+	struct xen_processor_px *dst_states = NULL;
+	int i;
+
+	BUILD_BUG_ON(sizeof(struct xen_processor_px) !=
+		     sizeof(struct acpi_processor_px));
+
+	dst_states = kcalloc(_pr->performance->state_count,
+			     sizeof(struct xen_processor_px), GFP_KERNEL);
+	if (!dst_states)
+		return ERR_PTR(-ENOMEM);
+
+	dst_perf->state_count = _pr->performance->state_count;
+	for (i = 0; i < _pr->performance->state_count; i++) {
+		/* Fortunatly for us, they are both the same size */
+		memcpy(&(dst_states[i]), &(_pr->performance->states[i]),
+		       sizeof(struct acpi_processor_px));
+	}
+	return dst_states;
+}
+static int xen_copy_psd_data(struct acpi_processor *_pr,
+			     struct xen_processor_performance *dst)
+{
+	BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
+		     sizeof(struct acpi_psd_package));
+
+	if (_pr->performance->shared_type != CPUFREQ_SHARED_TYPE_NONE) {
+		dst->shared_type = _pr->performance->shared_type;
+
+		memcpy(&(dst->domain_info), &(_pr->performance->domain_info),
+		       sizeof(struct acpi_psd_package));
+	} else {
+		if ((&cpu_data(0))->x86_vendor != X86_VENDOR_AMD)
+			return -EINVAL;
+
+		/* On AMD, the powernow-k8 is loaded before acpi_cpufreq
+		 * meaning that acpi_processor_preregister_performance never
+		 * gets called which would parse the _PSD. The only relevant
+		 * information from _PSD we need is whether it is HW_ALL or any
+		 * other type. AMD K8 >= are SW_ALL or SW_ANY, AMD K7<= HW_ANY.
+		 * This driver checks at the start whether it is K8 so it
+		 * if we get here it can only be K8.
+		 */
+		dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+		dst->domain_info.coord_type = DOMAIN_COORD_TYPE_SW_ANY;
+		dst->domain_info.num_processors = num_online_cpus();
+	}
+	return 0;
+}
+static int xen_copy_pct_data(struct acpi_pct_register *pct,
+			     struct xen_pct_register *dst_pct)
+{
+	/* It would be nice if you could just do 'memcpy(pct, dst_pct') but
+	 * sadly the Xen structure did not have the proper padding so the
+	 * descriptor field takes two (dst_pct) bytes instead of one (pct).
+	 */
+	dst_pct->descriptor = pct->descriptor;
+	dst_pct->length = pct->length;
+	dst_pct->space_id = pct->space_id;
+	dst_pct->bit_width = pct->bit_width;
+	dst_pct->bit_offset = pct->bit_offset;
+	dst_pct->reserved = pct->reserved;
+	dst_pct->address = pct->address;
+	return 0;
+}
+static int push_pxx_to_hypervisor(struct acpi_processor *_pr)
+{
+	int ret = 0;
+	struct xen_platform_op op = {
+		.cmd			= XENPF_set_processor_pminfo,
+		.interface_version	= XENPF_INTERFACE_VERSION,
+		.u.set_pminfo.id	= _pr->acpi_id,
+		.u.set_pminfo.type	= XEN_PM_PX,
+	};
+	struct xen_processor_performance *dst_perf;
+	struct xen_processor_px *dst_states = NULL;
+
+	dst_perf = &op.u.set_pminfo.perf;
+
+	dst_perf->platform_limit = _pr->performance_platform_limit;
+	dst_perf->flags |= XEN_PX_PPC;
+	xen_copy_pct_data(&(_pr->performance->control_register),
+			  &dst_perf->control_register);
+	xen_copy_pct_data(&(_pr->performance->status_register),
+			  &dst_perf->status_register);
+	dst_perf->flags |= XEN_PX_PCT;
+	dst_states = xen_copy_pss_data(_pr, dst_perf);
+	if (!IS_ERR_OR_NULL(dst_states)) {
+		set_xen_guest_handle(dst_perf->states, dst_states);
+		dst_perf->flags |= XEN_PX_PSS;
+	}
+	if (!xen_copy_psd_data(_pr, dst_perf))
+		dst_perf->flags |= XEN_PX_PSD;
+
+	if (!no_hypercall)
+		ret = HYPERVISOR_dom0_op(&op);
+
+	if (ret)
+		pr_err(DRV_NAME "(_PXX): Hypervisor error (%d) for ACPI ID %d\n",
+		       ret, _pr->acpi_id);
+
+	if (!IS_ERR_OR_NULL(dst_states))
+		kfree(dst_states);
+
+	return ret;
+}
+static int upload_pm_data(struct acpi_processor *_pr)
+{
+	int err = 0;
+
+	if (__test_and_set_bit(_pr->acpi_id, acpi_ids_done))
+		return -EBUSY;
+
+	if (_pr->flags.power)
+		err = push_cxx_to_hypervisor(_pr);
+
+	if (_pr->performance && _pr->performance->states)
+		err |= push_pxx_to_hypervisor(_pr);
+
+	return err;
+}
+static acpi_status
+read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+	u32 acpi_id;
+	acpi_status status;
+	acpi_object_type acpi_type;
+	unsigned long long tmp;
+	union acpi_object object = { 0 };
+	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
+
+	status = acpi_get_type(handle, &acpi_type);
+	if (ACPI_FAILURE(status))
+		return AE_OK;
+
+	switch (acpi_type) {
+	case ACPI_TYPE_PROCESSOR:
+		status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
+		if (ACPI_FAILURE(status))
+			return AE_OK;
+		acpi_id = object.processor.proc_id;
+		break;
+	case ACPI_TYPE_DEVICE:
+		status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
+		if (ACPI_FAILURE(status))
+			return AE_OK;
+		acpi_id = tmp;
+		break;
+	default:
+		return AE_OK;
+	}
+	if (acpi_id > NR_ACPI_CPUS) {
+		WARN_ONCE(1, "There are %d ACPI processors, but kernel can only do %d!\n",
+		     acpi_id, NR_ACPI_CPUS);
+		return AE_OK;
+	}
+	__set_bit(acpi_id, acpi_id_present);
+
+	return AE_OK;
+}
+static unsigned int more_acpi_ids(void)
+{
+	unsigned int n = 0;
+
+	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+			    ACPI_UINT32_MAX,
+			    read_acpi_id, NULL, NULL, NULL);
+	acpi_get_devices("ACPI0007", read_acpi_id, NULL, NULL);
+
+	mutex_lock(&acpi_ids_mutex);
+	if (!bitmap_equal(acpi_id_present, acpi_ids_done, MAX_ACPI_BITS))
+		n = bitmap_weight(acpi_id_present, MAX_ACPI_BITS);
+	mutex_unlock(&acpi_ids_mutex);
+
+	return n;
+}
+static void do_check_acpi_id_timer(struct work_struct *_work)
+{
+	/* All online CPUs have been processed at this stage. Now verify
+	 * whether in fact "online CPUs" == physical CPUs.
+	 */
+	acpi_id_present = kcalloc(MAX_ACPI_BITS, sizeof(unsigned long), GFP_KERNEL);
+	if (!acpi_id_present)
+		return;
+	memset(acpi_id_present, 0, MAX_ACPI_BITS * sizeof(unsigned long));
+
+	if (more_acpi_ids()) {
+		int cpu;
+		if (!pr_backup) {
+			schedule_delayed_work(&work, DELAY_TIMER);
+			return;
+		}
+		for_each_set_bit(cpu, acpi_id_present, MAX_ACPI_BITS) {
+			pr_backup->acpi_id = cpu;
+			mutex_lock(&acpi_ids_mutex);
+			(void)upload_pm_data(pr_backup);
+			mutex_unlock(&acpi_ids_mutex);
+		}
+	}
+	kfree(acpi_id_present);
+	acpi_id_present = NULL;
+}
+
+static int cpufreq_governor_xen(struct cpufreq_policy *policy,
+				unsigned int event)
+{
+	struct acpi_processor *_pr;
+
+	switch (event) {
+	case CPUFREQ_GOV_START:
+	case CPUFREQ_GOV_LIMITS:
+		/* Set it to max and let the hypervisor take over */
+		__cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
+
+		_pr = per_cpu(processors, policy->cpu /* APIC ID */);
+		if (!_pr)
+			break;
+
+		mutex_lock(&acpi_ids_mutex);
+		if (!pr_backup) {
+			pr_backup = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
+			memcpy(pr_backup, _pr, sizeof(struct acpi_processor));
+
+			INIT_DELAYED_WORK_DEFERRABLE(&work, do_check_acpi_id_timer);
+			schedule_delayed_work(&work, DELAY_TIMER);
+		}
+		(void)upload_pm_data(_pr);
+		mutex_unlock(&acpi_ids_mutex);
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+static struct cpufreq_governor cpufreq_gov_xen = {
+	.name		= "xen",
+	.governor	= cpufreq_governor_xen,
+	.owner		= THIS_MODULE,
+};
+static int __init check_prereq(void)
+{
+	struct cpuinfo_x86 *c = &cpu_data(0);
+
+	if (!xen_initial_domain())
+		return -ENODEV;
+
+	if (!acpi_gbl_FADT.smi_command)
+		return -ENODEV;
+
+	if (c->x86_vendor == X86_VENDOR_INTEL) {
+		if (!cpu_has(c, X86_FEATURE_EST))
+			return -ENODEV;
+
+		return 0;
+	}
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		u32 hi = 0, lo = 0;
+		/* Copied from powernow-k8.h, can't include ../cpufreq/powernow
+		 * as we get compile warnings for the static functions.
+		 */
+#define MSR_PSTATE_CUR_LIMIT    0xc0010061 /* pstate current limit MSR */
+		rdmsr(MSR_PSTATE_CUR_LIMIT, lo, hi);
+
+		/* If the MSR cannot provide the data, the powernow-k8
+		 * won't process the data properly either.
+		 */
+		if (hi || lo)
+			return 0;
+	}
+	return -ENODEV;
+}
+
+static int __init xen_processor_passthru_init(void)
+{
+	int rc = check_prereq();
+
+	if (rc)
+		return rc;
+
+	acpi_ids_done = kcalloc(MAX_ACPI_BITS, sizeof(unsigned long), GFP_KERNEL);
+	if (!acpi_ids_done)
+		return -ENOMEM;
+	memset(acpi_ids_done, 0, MAX_ACPI_BITS * sizeof(unsigned long));
+
+	return cpufreq_register_governor(&cpufreq_gov_xen);
+}
+static void __exit xen_processor_passthru_exit(void)
+{
+	cpufreq_unregister_governor(&cpufreq_gov_xen);
+	cancel_delayed_work_sync(&work);
+	kfree(acpi_ids_done);
+	kfree(pr_backup);
+}
+
+MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
+MODULE_DESCRIPTION("CPUfreq policy governor 'xen' which uploads PM data to Xen hypervisor");
+MODULE_LICENSE("GPL");
+
+late_initcall(xen_processor_passthru_init);
+module_exit(xen_processor_passthru_exit);
-- 
1.7.6.4