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Subject[PATCH 3/3] xen/processor-passthru: Provide an driver that passes struct acpi_processor data to the hypervisor.
Date
The ACPI processor processes the _Pxx and the _Cx state information
which are populated in the 'struct acpi_processor' per-cpu structure.
We read the contents of that structure and pass it up the Xen hypervisor.

The ACPI processor along with the CPU freq driver does all the heavy-lifting
for us (filtering, calling ACPI functions, etc) so that the contents is correct.
After we are done parsing the information, we wait in case of hotplug CPUs
get loaded and then pass that information 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]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/xen/Kconfig | 14 +
drivers/xen/Makefile | 2 +-
drivers/xen/processor-passthru.c | 492 ++++++++++++++++++++++++++++++++++++++
3 files changed, 507 insertions(+), 1 deletions(-)
create mode 100644 drivers/xen/processor-passthru.c

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index a1ced52..af5e062 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -178,4 +178,18 @@ config XEN_PRIVCMD
depends on XEN
default m

+config XEN_PROCESSOR_PASSTHRU
+ tristate "Processor passthrough driver for Xen"
+ depends on XEN
+ depends on ACPI_PROCESSOR
+ depends on X86
+ depends on CPU_FREQ
+ help
+ This driver parses the processor structure and passes the information
+ to the Xen hypervisor. It is used to allow the Xen hypervisor to have the
+ full power management data and be able to select proper Cx and Pxx states.
+
+ The driver should be loaded after acpi processor and cpufreq drivers have
+ been loaded. If you do not know what to choose, select M here.
+
endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index aa31337..ce235e7a 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
obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
obj-$(CONFIG_XEN_PRIVCMD) += xen-privcmd.o
-
+obj-$(CONFIG_XEN_PROCESSOR_PASSTHRU) += processor-passthru.o
xen-evtchn-y := evtchn.o
xen-gntdev-y := gntdev.o
xen-gntalloc-y := gntalloc.o
diff --git a/drivers/xen/processor-passthru.c b/drivers/xen/processor-passthru.c
new file mode 100644
index 0000000..e4dff42
--- /dev/null
+++ b/drivers/xen/processor-passthru.c
@@ -0,0 +1,492 @@
+/*
+ * 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/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 "xen-processor-thru"
+MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
+MODULE_DESCRIPTION("ACPI Power Management driver to pass Cx and Pxx data to Xen hypervisor");
+MODULE_LICENSE("GPL");
+
+
+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;
+
+
+#define POLL_TIMER msecs_to_jiffies(5000 /* 5 sec */)
+static struct task_struct *xen_processor_thread;
+
+static int xen_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 *xen_cx, *xen_cx_states = NULL;
+ struct acpi_processor_cx *cx;
+ int i, ok, ret = 0;
+
+ xen_cx_states = kcalloc(_pr->power.count,
+ sizeof(struct xen_processor_cx), GFP_KERNEL);
+ if (!xen_cx_states)
+ return -ENOMEM;
+
+ for (ok = 0, i = 1; i <= _pr->power.count; i++) {
+ cx = &_pr->power.states[i];
+ if (!cx->valid)
+ continue;
+
+ xen_cx = &(xen_cx_states[ok++]);
+
+ xen_cx->reg.space_id = ACPI_ADR_SPACE_SYSTEM_IO;
+ if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
+ xen_cx->reg.bit_width = 8;
+ xen_cx->reg.bit_offset = 0;
+ xen_cx->reg.access_size = 1;
+ } else {
+ xen_cx->reg.space_id = ACPI_ADR_SPACE_FIXED_HARDWARE;
+ if (cx->entry_method == ACPI_CSTATE_FFH) {
+ /* NATIVE_CSTATE_BEYOND_HALT */
+ xen_cx->reg.bit_offset = 2;
+ xen_cx->reg.bit_width = 1; /* VENDOR_INTEL */
+ }
+ xen_cx->reg.access_size = 0;
+ }
+ xen_cx->reg.address = cx->address;
+
+ xen_cx->type = cx->type;
+ xen_cx->latency = cx->latency;
+ xen_cx->power = cx->power;
+
+ xen_cx->dpcnt = 0;
+ set_xen_guest_handle(xen_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 available Cx info for cpu %d\n", _pr->acpi_id);
+ kfree(xen_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, xen_cx_states);
+
+ if (!no_hypercall)
+ ret = HYPERVISOR_dom0_op(&op);
+
+ if (ret)
+ pr_err(DRV_NAME "(CX): Hypervisor returned (%d) for ACPI ID: %d\n",
+ ret, _pr->acpi_id);
+
+ kfree(xen_cx_states);
+
+ return ret;
+}
+static struct xen_processor_px *xen_copy_pss_data(struct acpi_processor *_pr,
+ struct xen_processor_performance *xen_perf)
+{
+ struct xen_processor_px *xen_states = NULL;
+ int i;
+
+ BUILD_BUG_ON(sizeof(struct xen_processor_px) !=
+ sizeof(struct acpi_processor_px));
+
+ xen_states = kcalloc(_pr->performance->state_count,
+ sizeof(struct xen_processor_px), GFP_KERNEL);
+ if (!xen_states)
+ return ERR_PTR(-ENOMEM);
+
+ xen_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(&(xen_states[i]), &(_pr->performance->states[i]),
+ sizeof(struct acpi_processor_px));
+ }
+ return xen_states;
+}
+static int xen_copy_psd_data(struct acpi_processor *_pr,
+ struct xen_processor_performance *xen_perf)
+{
+ BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
+ sizeof(struct acpi_psd_package));
+
+ if (_pr->performance->shared_type != CPUFREQ_SHARED_TYPE_NONE) {
+ xen_perf->shared_type = _pr->performance->shared_type;
+
+ memcpy(&(xen_perf->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.
+ */
+ xen_perf->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+ xen_perf->domain_info.coord_type = DOMAIN_COORD_TYPE_SW_ANY;
+ xen_perf->domain_info.num_processors = num_online_cpus();
+ }
+ return 0;
+}
+static int xen_copy_pct_data(struct acpi_pct_register *pct,
+ struct xen_pct_register *_pct)
+{
+ /* It would be nice if you could just do 'memcpy(pct, _pct') but
+ * sadly the Xen structure did not have the proper padding
+ * so the descriptor field takes two (_pct) bytes instead of one (pct).
+ */
+ _pct->descriptor = pct->descriptor;
+ _pct->length = pct->length;
+ _pct->space_id = pct->space_id;
+ _pct->bit_width = pct->bit_width;
+ _pct->bit_offset = pct->bit_offset;
+ _pct->reserved = pct->reserved;
+ _pct->address = pct->address;
+ return 0;
+}
+static int xen_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 *xen_perf;
+ struct xen_processor_px *xen_states = NULL;
+
+ xen_perf = &op.u.set_pminfo.perf;
+
+ xen_perf->platform_limit = _pr->performance_platform_limit;
+ xen_perf->flags |= XEN_PX_PPC;
+ xen_copy_pct_data(&(_pr->performance->control_register),
+ &xen_perf->control_register);
+ xen_copy_pct_data(&(_pr->performance->status_register),
+ &xen_perf->status_register);
+ xen_perf->flags |= XEN_PX_PCT;
+ xen_states = xen_copy_pss_data(_pr, xen_perf);
+ if (!IS_ERR_OR_NULL(xen_states)) {
+ set_xen_guest_handle(xen_perf->states, xen_states);
+ xen_perf->flags |= XEN_PX_PSS;
+ }
+ if (!xen_copy_psd_data(_pr, xen_perf))
+ xen_perf->flags |= XEN_PX_PSD;
+
+ if (!no_hypercall)
+ ret = HYPERVISOR_dom0_op(&op);
+
+ if (ret)
+ pr_err(DRV_NAME "(_PXX): Hypervisor returned (%d) for ACPI ID %d\n",
+ ret, _pr->acpi_id);
+
+ if (!IS_ERR_OR_NULL(xen_states))
+ kfree(xen_states);
+
+ return ret;
+}
+/*
+ * We read out the struct acpi_processor, and serialize access
+ * so that there is only one caller. This is so that we won't
+ * race with the CPU hotplug code (xen_cpu_soft_notify).
+ */
+static int xen_process_data(struct acpi_processor *_pr)
+{
+ int err = 0;
+
+ mutex_lock(&acpi_ids_mutex);
+ if (__test_and_set_bit(_pr->acpi_id, acpi_ids_done)) {
+ mutex_unlock(&acpi_ids_mutex);
+ return -EBUSY;
+ }
+ if (_pr->flags.power)
+ err = xen_push_cxx_to_hypervisor(_pr);
+
+ if (_pr->performance && _pr->performance->states)
+ err |= xen_push_pxx_to_hypervisor(_pr);
+
+ mutex_unlock(&acpi_ids_mutex);
+ return err;
+}
+static acpi_status
+xen_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 xen_acpi_ids_more(void)
+{
+ unsigned int n = 0;
+
+ acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+ ACPI_UINT32_MAX,
+ xen_read_acpi_id, NULL, NULL, NULL);
+ acpi_get_devices("ACPI0007", xen_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 int xen_processor_check(void)
+{
+ struct cpufreq_policy *policy;
+ struct acpi_processor *pr_backup = NULL;
+ int cpu, err = 0;
+
+ cpu = get_cpu();
+ put_cpu();
+ policy = cpufreq_cpu_get(cpu);
+ if (!policy)
+ return -EBUSY;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu) {
+ struct acpi_processor *_pr;
+
+ _pr = per_cpu(processors, cpu /* APIC ID */);
+ if (!_pr)
+ continue;
+
+ if (!pr_backup) {
+ pr_backup = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
+ memcpy(pr_backup, _pr, sizeof(struct acpi_processor));
+ }
+ (void)xen_process_data(_pr);
+ }
+ put_online_cpus();
+
+ cpufreq_cpu_put(policy);
+
+ /* 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) {
+ err = -ENOMEM;
+ goto err_out;
+ }
+ memset(acpi_id_present, 0, MAX_ACPI_BITS * sizeof(unsigned long));
+
+ if (xen_acpi_ids_more() && pr_backup) {
+ for_each_set_bit(cpu, acpi_id_present, MAX_ACPI_BITS) {
+ pr_backup->acpi_id = cpu;
+ /* We will get -EBUSY if it has been programmed already. */
+ (void)xen_process_data(pr_backup);
+ }
+ }
+ kfree(acpi_id_present);
+ acpi_id_present = NULL;
+err_out:
+ kfree(pr_backup);
+ pr_backup = NULL;
+ return err;
+}
+/*
+ * The purpose of this timer/thread is to wait for the ACPI processor
+ * and CPUfreq drivers to load up and parse the Pxx and Cxx information
+ * before we attempt to read it.
+ */
+static void xen_processor_timeout(unsigned long arg)
+{
+ wake_up_process((struct task_struct *)arg);
+}
+static int xen_processor_thread_func(void *dummy)
+{
+ struct timer_list timer;
+ int err = 0;
+
+ setup_deferrable_timer_on_stack(&timer, xen_processor_timeout,
+ (unsigned long)current);
+ do {
+ __set_current_state(TASK_INTERRUPTIBLE);
+ mod_timer(&timer, jiffies + POLL_TIMER);
+ schedule();
+ err = xen_processor_check();
+ if (err != -EBUSY)
+ break;
+ } while (!kthread_should_stop());
+
+ if (err)
+ pr_err(DRV_NAME ": Failed to upload data (%d)!\n", err);
+ del_timer_sync(&timer);
+ destroy_timer_on_stack(&timer);
+ return 0;
+}
+
+static int xen_cpu_soft_notify(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct acpi_processor *_pr = per_cpu(processors, cpu);
+
+ if (action == CPU_ONLINE && _pr)
+ (void)xen_process_data(_pr);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block xen_cpu_notifier = {
+ .notifier_call = xen_cpu_soft_notify,
+ .priority = -1, /* Be the last one */
+};
+
+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));
+ xen_processor_thread = kthread_run(xen_processor_thread_func, NULL, DRV_NAME);
+ if (IS_ERR(xen_processor_thread)) {
+ pr_err(DRV_NAME ": Failed to create thread. Aborting.\n");
+ return -ENOMEM;
+ }
+ register_hotcpu_notifier(&xen_cpu_notifier);
+ return 0;
+}
+static void __exit xen_processor_passthru_exit(void)
+{
+ unregister_hotcpu_notifier(&xen_cpu_notifier);
+ if (xen_processor_thread)
+ kthread_stop(xen_processor_thread);
+ kfree(acpi_ids_done);
+}
+late_initcall(xen_processor_passthru_init);
+module_exit(xen_processor_passthru_exit);
--
1.7.9.48.g85da4d
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