4 files changed, 597 insertions, 1 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index a1ced521cf74..648bcd4195c5 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -178,4 +178,21 @@ config XEN_PRIVCMD
         depends on XEN
         default m
 
+config XEN_ACPI_PROCESSOR
+        tristate "Xen ACPI processor"
+        depends on XEN && X86 && ACPI_PROCESSOR
+        default y if (X86_ACPI_CPUFREQ = y || X86_POWERNOW_K8 = y)
+        default m if (X86_ACPI_CPUFREQ = m || X86_POWERNOW_K8 = m)
+        help
+          This ACPI processor uploads Power Management information 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. It also registers itslef as the SMM so that
+          other drivers (such as ACPI cpufreq scaling driver) will not load.
+
+          To compile this driver as a module, choose M here: the
+          module will be called xen_acpi_processor  If you do not know what to choose,
+          select M here. If the CPUFREQ drivers are built in, select Y here.
+
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index aa31337192cc..9adc5be57b13 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_ACPI_PROCESSOR)        += xen-acpi-processor.o
 xen-evtchn-y                            := evtchn.o
 xen-gntdev-y                            := gntdev.o
 xen-gntalloc-y                          := gntalloc.o
diff --git a/drivers/xen/xen-acpi-processor.c b/drivers/xen/xen-acpi-processor.c
new file mode 100644
index 000000000000..5c2be963aa18
--- /dev/null
+++ b/drivers/xen/xen-acpi-processor.c
@@ -0,0 +1,562 @@
+/*
+ * 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 "xen-acpi-processor: "
+
+static int no_hypercall;
+MODULE_PARM_DESC(off, "Inhibit the hypercall.");
+module_param_named(off, no_hypercall, int, 0400);
+
+/*
+ * Note: Do not convert the acpi_id* below 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. Instead use the 'nr_acpi_bits'
+ * which is dynamically computed based on the MADT or x2APIC table.
+ */
+static unsigned int nr_acpi_bits;
+/* Mutex to protect the acpi_ids_done - for CPU hotplug use. */
+static DEFINE_MUTEX(acpi_ids_mutex);
+/* Which ACPI ID we have processed from 'struct acpi_processor'. */
+static unsigned long *acpi_ids_done;
+/* Which ACPI ID exist in the SSDT/DSDT processor definitions. */
+static unsigned long __initdata *acpi_id_present;
+/* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
+static unsigned long __initdata *acpi_id_cst_present;
+
+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;
+        unsigned int i, ok;
+        int 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);
+        }
+        if (!ok) {
+                pr_debug(DRV_NAME "No _Cx for ACPI CPU %u\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_debug("ACPI CPU%u - C-states uploaded.\n", _pr->acpi_id);
+                for (i = 1; i <= _pr->power.count; i++) {
+                        cx = &_pr->power.states[i];
+                        if (!cx->valid)
+                                continue;
+                        pr_debug("     C%d: %s %d uS\n",
+                                 cx->type, cx->desc, (u32)cx->latency);
+                }
+        } else
+                pr_err(DRV_NAME "(CX): Hypervisor error (%d) for ACPI CPU%u\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;
+        unsigned 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)
+{
+        struct acpi_psd_package *pdomain;
+
+        BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
+                     sizeof(struct acpi_psd_package));
+
+        /* This information is enumerated only if acpi_processor_preregister_performance
+         * has been called.
+         */
+        dst->shared_type = _pr->performance->shared_type;
+
+        pdomain = &(_pr->performance->domain_info);
+
+        /* 'acpi_processor_preregister_performance' does not parse if the
+         * num_processors <= 1, but Xen still requires it. Do it manually here.
+         */
+        if (pdomain->num_processors <= 1) {
+                if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
+                        dst->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+                else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
+                        dst->shared_type = CPUFREQ_SHARED_TYPE_HW;
+                else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
+                        dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+
+        }
+        memcpy(&(dst->domain_info), pdomain, sizeof(struct acpi_psd_package));
+        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 (dst_perf->flags != (XEN_PX_PSD | XEN_PX_PSS | XEN_PX_PCT | XEN_PX_PPC)) {
+                pr_warn(DRV_NAME "ACPI CPU%u missing some P-state data (%x), skipping.\n",
+                        _pr->acpi_id, dst_perf->flags);
+                ret = -ENODEV;
+                goto err_free;
+        }
+
+        if (!no_hypercall)
+                ret = HYPERVISOR_dom0_op(&op);
+
+        if (!ret) {
+                struct acpi_processor_performance *perf;
+                unsigned int i;
+
+                perf = _pr->performance;
+                pr_debug("ACPI CPU%u - P-states uploaded.\n", _pr->acpi_id);
+                for (i = 0; i < perf->state_count; i++) {
+                        pr_debug("     %cP%d: %d MHz, %d mW, %d uS\n",
+                        (i == perf->state ? '*' : ' '), i,
+                        (u32) perf->states[i].core_frequency,
+                        (u32) perf->states[i].power,
+                        (u32) perf->states[i].transition_latency);
+                }
+        } else if (ret != -EINVAL)
+                /* EINVAL means the ACPI ID is incorrect - meaning the ACPI
+                 * table is referencing a non-existing CPU - which can happen
+                 * with broken ACPI tables. */
+                pr_warn(DRV_NAME "(_PXX): Hypervisor error (%d) for ACPI CPU%u\n",
+                       ret, _pr->acpi_id);
+err_free:
+        if (!IS_ERR_OR_NULL(dst_states))
+                kfree(dst_states);
+
+        return ret;
+}
+static int upload_pm_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 = push_cxx_to_hypervisor(_pr);
+
+        if (_pr->performance && _pr->performance->states)
+                err |= push_pxx_to_hypervisor(_pr);
+
+        mutex_unlock(&acpi_ids_mutex);
+        return err;
+}
+static unsigned int __init get_max_acpi_id(void)
+{
+        struct xenpf_pcpuinfo *info;
+        struct xen_platform_op op = {
+                .cmd = XENPF_get_cpuinfo,
+                .interface_version = XENPF_INTERFACE_VERSION,
+        };
+        int ret = 0;
+        unsigned int i, last_cpu, max_acpi_id = 0;
+
+        info = &op.u.pcpu_info;
+        info->xen_cpuid = 0;
+
+        ret = HYPERVISOR_dom0_op(&op);
+        if (ret)
+                return NR_CPUS;
+
+        /* The max_present is the same irregardless of the xen_cpuid */
+        last_cpu = op.u.pcpu_info.max_present;
+        for (i = 0; i <= last_cpu; i++) {
+                info->xen_cpuid = i;
+                ret = HYPERVISOR_dom0_op(&op);
+                if (ret)
+                        continue;
+                max_acpi_id = max(info->acpi_id, max_acpi_id);
+        }
+        max_acpi_id *= 2; /* Slack for CPU hotplug support. */
+        pr_debug(DRV_NAME "Max ACPI ID: %u\n", max_acpi_id);
+        return max_acpi_id;
+}
+/*
+ * The read_acpi_id and check_acpi_ids are there to support the Xen
+ * oddity of virtual CPUs != physical CPUs in the initial domain.
+ * The user can supply 'xen_max_vcpus=X' on the Xen hypervisor line
+ * which will band the amount of CPUs the initial domain can see.
+ * In general that is OK, except it plays havoc with any of the
+ * for_each_[present|online]_cpu macros which are banded to the virtual
+ * CPU amount.
+ */
+static acpi_status __init
+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 };
+        acpi_io_address pblk = 0;
+
+        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;
+                pblk = object.processor.pblk_address;
+                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;
+        }
+        /* There are more ACPI Processor objects than in x2APIC or MADT.
+         * This can happen with incorrect ACPI SSDT declerations. */
+        if (acpi_id > nr_acpi_bits) {
+                pr_debug(DRV_NAME "We only have %u, trying to set %u\n",
+                         nr_acpi_bits, acpi_id);
+                return AE_OK;
+        }
+        /* OK, There is a ACPI Processor object */
+        __set_bit(acpi_id, acpi_id_present);
+
+        pr_debug(DRV_NAME "ACPI CPU%u w/ PBLK:0x%lx\n", acpi_id,
+                 (unsigned long)pblk);
+
+        status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
+        if (ACPI_FAILURE(status)) {
+                if (!pblk)
+                        return AE_OK;
+        }
+        /* .. and it has a C-state */
+        __set_bit(acpi_id, acpi_id_cst_present);
+
+        return AE_OK;
+}
+static int __init check_acpi_ids(struct acpi_processor *pr_backup)
+{
+
+        if (!pr_backup)
+                return -ENODEV;
+
+        /* All online CPUs have been processed at this stage. Now verify
+         * whether in fact "online CPUs" == physical CPUs.
+         */
+        acpi_id_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
+        if (!acpi_id_present)
+                return -ENOMEM;
+
+        acpi_id_cst_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
+        if (!acpi_id_cst_present) {
+                kfree(acpi_id_present);
+                return -ENOMEM;
+        }
+
+        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);
+
+        if (!bitmap_equal(acpi_id_present, acpi_ids_done, nr_acpi_bits)) {
+                unsigned int i;
+                for_each_set_bit(i, acpi_id_present, nr_acpi_bits) {
+                        pr_backup->acpi_id = i;
+                        /* Mask out C-states if there are no _CST or PBLK */
+                        pr_backup->flags.power = test_bit(i, acpi_id_cst_present);
+                        (void)upload_pm_data(pr_backup);
+                }
+        }
+        kfree(acpi_id_present);
+        acpi_id_present = NULL;
+        kfree(acpi_id_cst_present);
+        acpi_id_cst_present = NULL;
+        return 0;
+}
+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) {
+                /* Copied from powernow-k8.h, can't include ../cpufreq/powernow
+                 * as we get compile warnings for the static functions.
+                 */
+#define CPUID_FREQ_VOLT_CAPABILITIES    0x80000007
+#define USE_HW_PSTATE                   0x00000080
+                u32 eax, ebx, ecx, edx;
+                cpuid(CPUID_FREQ_VOLT_CAPABILITIES, &eax, &ebx, &ecx, &edx);
+                if ((edx & USE_HW_PSTATE) != USE_HW_PSTATE)
+                        return -ENODEV;
+                return 0;
+        }
+        return -ENODEV;
+}
+/* acpi_perf_data is a pointer to percpu data. */
+static struct acpi_processor_performance __percpu *acpi_perf_data;
+
+static void free_acpi_perf_data(void)
+{
+        unsigned int i;
+
+        /* Freeing a NULL pointer is OK, and alloc_percpu zeroes. */
+        for_each_possible_cpu(i)
+                free_cpumask_var(per_cpu_ptr(acpi_perf_data, i)
+                                 ->shared_cpu_map);
+        free_percpu(acpi_perf_data);
+}
+
+static int __init xen_acpi_processor_init(void)
+{
+        struct acpi_processor *pr_backup = NULL;
+        unsigned int i;
+        int rc = check_prereq();
+
+        if (rc)
+                return rc;
+
+        nr_acpi_bits = get_max_acpi_id() + 1;
+        acpi_ids_done = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
+        if (!acpi_ids_done)
+                return -ENOMEM;
+
+        acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
+        if (!acpi_perf_data) {
+                pr_debug(DRV_NAME "Memory allocation error for acpi_perf_data.\n");
+                kfree(acpi_ids_done);
+                return -ENOMEM;
+        }
+        for_each_possible_cpu(i) {
+                if (!zalloc_cpumask_var_node(
+                        &per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
+                        GFP_KERNEL, cpu_to_node(i))) {
+                        rc = -ENOMEM;
+                        goto err_out;
+                }
+        }
+
+        /* Do initialization in ACPI core. It is OK to fail here. */
+        (void)acpi_processor_preregister_performance(acpi_perf_data);
+
+        for_each_possible_cpu(i) {
+                struct acpi_processor_performance *perf;
+
+                perf = per_cpu_ptr(acpi_perf_data, i);
+                rc = acpi_processor_register_performance(perf, i);
+                if (WARN_ON(rc))
+                        goto err_out;
+        }
+        rc = acpi_processor_notify_smm(THIS_MODULE);
+        if (WARN_ON(rc))
+                goto err_unregister;
+
+        for_each_possible_cpu(i) {
+                struct acpi_processor *_pr;
+                _pr = per_cpu(processors, i /* 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)upload_pm_data(_pr);
+        }
+        rc = check_acpi_ids(pr_backup);
+        if (rc)
+                goto err_unregister;
+
+        kfree(pr_backup);
+
+        return 0;
+err_unregister:
+        for_each_possible_cpu(i) {
+                struct acpi_processor_performance *perf;
+                perf = per_cpu_ptr(acpi_perf_data, i);
+                acpi_processor_unregister_performance(perf, i);
+        }
+err_out:
+        /* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
+        free_acpi_perf_data();
+        kfree(acpi_ids_done);
+        return rc;
+}
+static void __exit xen_acpi_processor_exit(void)
+{
+        int i;
+
+        kfree(acpi_ids_done);
+        for_each_possible_cpu(i) {
+                struct acpi_processor_performance *perf;
+                perf = per_cpu_ptr(acpi_perf_data, i);
+                acpi_processor_unregister_performance(perf, i);
+        }
+        free_acpi_perf_data();
+}
+
+MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
+MODULE_DESCRIPTION("Xen ACPI Processor P-states (and Cx) driver which uploads PM data to Xen hypervisor");
+MODULE_LICENSE("GPL");
+
+/* We want to be loaded before the CPU freq scaling drivers are loaded.
+ * They are loaded in late_initcall. */
+device_initcall(xen_acpi_processor_init);
+module_exit(xen_acpi_processor_exit);
diff --git a/include/xen/interface/platform.h b/include/xen/interface/platform.h
index 861b359b44aa..486653f0dd8f 100644
--- a/include/xen/interface/platform.h
+++ b/include/xen/interface/platform.h
@@ -298,6 +298,22 @@ struct xenpf_set_processor_pminfo {
 };
 DEFINE_GUEST_HANDLE_STRUCT(xenpf_set_processor_pminfo);
 
+#define XENPF_get_cpuinfo 55
+struct xenpf_pcpuinfo {
+        /* IN */
+        uint32_t xen_cpuid;
+        /* OUT */
+        /* The maxium cpu_id that is present */
+        uint32_t max_present;
+#define XEN_PCPU_FLAGS_ONLINE   1
+        /* Correponding xen_cpuid is not present*/
+#define XEN_PCPU_FLAGS_INVALID  2
+        uint32_t flags;
+        uint32_t apic_id;
+        uint32_t acpi_id;
+};
+DEFINE_GUEST_HANDLE_STRUCT(xenpf_pcpuinfo);
+
 struct xen_platform_op {
         uint32_t cmd;
         uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
@@ -313,6 +329,7 @@ struct xen_platform_op {
                 struct xenpf_change_freq       change_freq;
                 struct xenpf_getidletime       getidletime;
                 struct xenpf_set_processor_pminfo set_pminfo;
+                struct xenpf_pcpuinfo          pcpu_info;
                 uint8_t                        pad[128];
         } u;
 };