Message-Id: <1277112703.2096.511.camel@ymzhang.sh.intel.com>
Date:	Mon, 21 Jun 2010 17:31:43 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	LKML <linux-kernel@...r.kernel.org>, kvm@...r.kernel.org,
	Avi Kivity <avi@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Fr??d??ric Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Lin Ming <ming.m.lin@...el.com>,
	Sheng Yang <sheng@...ux.intel.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	oerg Roedel <joro@...tes.org>,
	Jes Sorensen <Jes.Sorensen@...hat.com>,
	Gleb Natapov <gleb@...hat.com>,
	Zachary Amsden <zamsden@...hat.com>, zhiteng.huang@...el.com,
	tim.c.chen@...el.com
Subject: [PATCH V2 3/5] ara virt interface of perf to support kvm guest os
 statistics collection in guest os

The 3rd patch is to implement para virt perf at host kernel.

Signed-off-by: Zhang Yanmin <yanmin_zhang@...ux.intel.com>

---

--- linux-2.6_tip0620/arch/x86/include/asm/kvm_para.h	2010-06-21 15:19:38.992999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/include/asm/kvm_para.h	2010-06-21 15:21:39.308999849 +0800
@@ -2,6 +2,7 @@
 #define _ASM_X86_KVM_PARA_H
 
 #include <linux/types.h>
+#include <linux/list.h>
 #include <asm/hyperv.h>
 
 /* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
@@ -19,7 +20,8 @@
 /* This indicates that the new set of kvmclock msrs
  * are available. The use of 0x11 and 0x12 is deprecated
  */
-#define KVM_FEATURE_CLOCKSOURCE2        3
+#define KVM_FEATURE_CLOCKSOURCE2	3
+#define KVM_FEATURE_PV_PERF		4
 
 /* The last 8 bits are used to indicate how to interpret the flags field
  * in pvclock structure. If no bits are set, all flags are ignored.
@@ -33,7 +35,14 @@
 #define MSR_KVM_WALL_CLOCK_NEW  0x4b564d00
 #define MSR_KVM_SYSTEM_TIME_NEW 0x4b564d01
 
-#define KVM_MAX_MMU_OP_BATCH           32
+#define KVM_MAX_MMU_OP_BATCH		32
+
+/* Operations for KVM_PERF_OP */
+#define KVM_PERF_OP_OPEN		1
+#define KVM_PERF_OP_CLOSE		2
+#define KVM_PERF_OP_ENABLE		3
+#define KVM_PERF_OP_DISABLE		4
+#define KVM_PERF_OP_READ		5
 
 /* Operations for KVM_HC_MMU_OP */
 #define KVM_MMU_OP_WRITE_PTE            1
@@ -64,6 +73,85 @@ struct kvm_mmu_op_release_pt {
 #ifdef __KERNEL__
 #include <asm/processor.h>
 
+/*
+ * data communication area about perf_event between
+ * Host kernel and guest kernel
+ */
+struct guest_perf_event {
+	u64 count;
+	atomic_t overflows;
+};
+
+/*
+ * In host kernel, perf_event->host_perf_shadow points to
+ * host_perf_shadow which records some information
+ * about the guest.
+ */
+struct host_perf_shadow {
+	/* guest perf_event id passed from guest os */
+	int id;
+	/*
+	 * Host kernel saves data into data member counter firstly.
+	 * kvm will get data from this counter and calls kvm functions
+	 * to copy or add data back to guets os before entering guest os
+	 * next time
+	 */
+	struct guest_perf_event counter;
+	/* guest_event_addr is gpa_t pointing to guest os guest_perf_event*/
+	__u64 guest_event_addr;
+
+	/*
+	 * Link to  of kvm.kvm_arch.shadow_hash_table
+	 */
+	struct list_head shadow_entry;
+	struct kvm_vcpu *vcpu;
+
+	struct perf_event *host_event;
+	/*
+	 * Below counter is to prevent malicious guest os to try to
+	 * close/enable event at the same time.
+	 */
+	atomic_t ref_counter;
+};
+
+/*
+ * In guest kernel, perf_event->guest_shadow points to
+ * guest_perf_shadow which records some information
+ * about the guest.
+ */
+struct guest_perf_shadow {
+	/* guest perf_event id passed from guest os */
+	int id;
+	/*
+	 * Host kernel kvm saves data into data member counter
+	 */
+	struct guest_perf_event counter;
+};
+
+/*
+ * guest_perf_attr is used when guest calls hypercall to
+ * open a new perf_event at host side. Mostly, it's a copy of
+ * perf_event_attr and deletes something not used by host kernel.
+ */
+struct guest_perf_attr {
+	__u32			type;
+	__u64			config;
+	__u64			sample_period;
+	__u64			sample_type;
+	__u64			read_format;
+	__u64			flags;
+	__u32			bp_type;
+	__u64			bp_addr;
+	__u64			bp_len;
+};
+
+struct guest_perf_event_param {
+	__u64 attr_addr;
+	__u64 guest_event_addr;
+	/* In case there is an alignment issue, we put id as the last one */
+	int id;
+};
+
 extern void kvmclock_init(void);
 
 
--- linux-2.6_tip0620/arch/x86/include/asm/kvm_host.h	2010-06-21 15:19:39.019999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/include/asm/kvm_host.h	2010-06-21 15:21:39.308999849 +0800
@@ -24,6 +24,7 @@
 #include <asm/desc.h>
 #include <asm/mtrr.h>
 #include <asm/msr-index.h>
+#include <asm/perf_event.h>
 
 #define KVM_MAX_VCPUS 64
 #define KVM_MEMORY_SLOTS 32
@@ -360,6 +361,18 @@ struct kvm_vcpu_arch {
 
 	/* fields used by HYPER-V emulation */
 	u64 hv_vapic;
+
+	/*
+	 * Fields used by PARAVIRT perf interface:
+	 *
+	 * kvm checks overflow_events before entering guest os,
+	 * and copy data back to guest os.
+	 * event_mutex is to avoid a race between NMI perf event overflow
+	 * handler, event close, and enable/disable.
+	 */
+	struct mutex event_mutex;
+	int overflows;
+	struct perf_event *overflow_events[X86_PMC_IDX_MAX];
 };
 
 struct kvm_mem_alias {
@@ -377,6 +390,9 @@ struct kvm_mem_aliases {
 	int naliases;
 };
 
+#define KVM_PARAVIRT_PERF_EVENT_ENTRY_BITS	(10)
+#define KVM_PARAVIRT_PERF_EVENT_ENTRY_NUM	(1<<KVM_PARAVIRT_PERF_EVENT_ENTRY_BITS)
+
 struct kvm_arch {
 	struct kvm_mem_aliases *aliases;
 
@@ -415,6 +431,15 @@ struct kvm_arch {
 	/* fields used by HYPER-V emulation */
 	u64 hv_guest_os_id;
 	u64 hv_hypercall;
+
+	/*
+	 * fields used by PARAVIRT perf interface:
+	 * Used to organize all host perf_events representing guest
+	 * perf_event on a specific kvm instance
+	 */
+	atomic_t kvm_pv_event_num;
+	spinlock_t shadow_lock;
+	struct list_head *shadow_hash_table;
 };
 
 struct kvm_vm_stat {
@@ -561,6 +586,9 @@ int emulator_write_phys(struct kvm_vcpu 
 			  const void *val, int bytes);
 int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
 		  gpa_t addr, unsigned long *ret);
+int kvm_pv_perf_op(struct kvm_vcpu *vcpu, int op_code, unsigned long a1,
+		   unsigned long a2, unsigned long *result);
+
 u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
 
 extern bool tdp_enabled;
--- linux-2.6_tip0620/include/linux/kvm_para.h	2010-06-21 15:19:53.309999849 +0800
+++ linux-2.6_tip0620perfkvm/include/linux/kvm_para.h	2010-06-21 15:21:39.312999849 +0800
@@ -17,6 +17,7 @@
 
 #define KVM_HC_VAPIC_POLL_IRQ		1
 #define KVM_HC_MMU_OP			2
+#define KVM_PERF_OP			3
 
 /*
  * hypercalls use architecture specific
--- linux-2.6_tip0620/arch/x86/kvm/vmx.c	2010-06-21 15:19:39.322999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/kvm/vmx.c	2010-06-21 15:21:39.310999849 +0800
@@ -3647,6 +3647,7 @@ static int vmx_handle_exit(struct kvm_vc
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u32 exit_reason = vmx->exit_reason;
 	u32 vectoring_info = vmx->idt_vectoring_info;
+	int ret;
 
 	trace_kvm_exit(exit_reason, vcpu);
 
@@ -3694,12 +3695,17 @@ static int vmx_handle_exit(struct kvm_vc
 
 	if (exit_reason < kvm_vmx_max_exit_handlers
 	    && kvm_vmx_exit_handlers[exit_reason])
-		return kvm_vmx_exit_handlers[exit_reason](vcpu);
+		ret = kvm_vmx_exit_handlers[exit_reason](vcpu);
 	else {
 		vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
 		vcpu->run->hw.hardware_exit_reason = exit_reason;
+		ret = 0;
 	}
-	return 0;
+
+	/* sync paravirt perf event to guest */
+	kvm_sync_events_to_guest(vcpu);
+
+	return ret;
 }
 
 static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
--- linux-2.6_tip0620/arch/x86/kvm/x86.c	2010-06-21 15:19:39.315999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/kvm/x86.c	2010-06-21 16:49:58.182999849 +0800
@@ -6,12 +6,14 @@
  * Copyright (C) 2006 Qumranet, Inc.
  * Copyright (C) 2008 Qumranet, Inc.
  * Copyright IBM Corporation, 2008
+ * Copyright Intel Corporation, 2010
  *
  * Authors:
  *   Avi Kivity   <avi@...ranet.com>
  *   Yaniv Kamay  <yaniv@...ranet.com>
  *   Amit Shah    <amit.shah@...ranet.com>
  *   Ben-Ami Yassour <benami@...ibm.com>
+ *   Yanmin Zhang <yanmin.zhang@...el.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -1618,6 +1620,7 @@ int kvm_dev_ioctl_check_extension(long e
 	case KVM_CAP_PCI_SEGMENT:
 	case KVM_CAP_DEBUGREGS:
 	case KVM_CAP_X86_ROBUST_SINGLESTEP:
+	case KVM_CAP_PV_PERF:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
@@ -1993,7 +1996,9 @@ static void do_cpuid_ent(struct kvm_cpui
 		entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
 			     (1 << KVM_FEATURE_NOP_IO_DELAY) |
 			     (1 << KVM_FEATURE_CLOCKSOURCE2) |
+			     (1 << KVM_FEATURE_PV_PERF) |
 			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
+
 		entry->ebx = 0;
 		entry->ecx = 0;
 		entry->edx = 0;
@@ -4052,10 +4057,21 @@ static unsigned long kvm_get_guest_ip(vo
 	return ip;
 }
 
+int kvm_notify_event_overflow(void)
+{
+	if (percpu_read(current_vcpu)) {
+		kvm_inject_nmi(percpu_read(current_vcpu));
+		return 0;
+	}
+
+	return -1;
+}
+
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.is_in_guest		= kvm_is_in_guest,
 	.is_user_mode		= kvm_is_user_mode,
 	.get_guest_ip		= kvm_get_guest_ip,
+	.copy_event_to_shadow	= kvm_copy_event_to_shadow,
 };
 
 void kvm_before_handle_nmi(struct kvm_vcpu *vcpu)
@@ -4138,15 +4154,6 @@ int kvm_emulate_halt(struct kvm_vcpu *vc
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_halt);
 
-static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
-			   unsigned long a1)
-{
-	if (is_long_mode(vcpu))
-		return a0;
-	else
-		return a0 | ((gpa_t)a1 << 32);
-}
-
 int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
 	u64 param, ingpa, outgpa, ret;
@@ -4245,6 +4252,9 @@ int kvm_emulate_hypercall(struct kvm_vcp
 	case KVM_HC_MMU_OP:
 		r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
 		break;
+	case KVM_PERF_OP:
+		r = kvm_pv_perf_op(vcpu, a0, a1, a2, &ret);
+		break;
 	default:
 		ret = -KVM_ENOSYS;
 		break;
@@ -5334,6 +5344,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *
 	}
 	vcpu->arch.mcg_cap = KVM_MAX_MCE_BANKS;
 
+	mutex_init(&vcpu->arch.event_mutex);
+
 	return 0;
 fail_free_lapic:
 	kvm_free_lapic(vcpu);
@@ -5360,6 +5372,8 @@ void kvm_arch_vcpu_uninit(struct kvm_vcp
 struct  kvm *kvm_arch_create_vm(void)
 {
 	struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
+	struct list_head *hash_table;
+	int i;
 
 	if (!kvm)
 		return ERR_PTR(-ENOMEM);
@@ -5369,6 +5383,18 @@ struct  kvm *kvm_arch_create_vm(void)
 		kfree(kvm);
 		return ERR_PTR(-ENOMEM);
 	}
+	hash_table = kmalloc(sizeof(struct list_head) *
+			KVM_PARAVIRT_PERF_EVENT_ENTRY_NUM,
+			GFP_KERNEL);
+	if (!hash_table) {
+		kfree(kvm->arch.aliases);
+		kfree(kvm);
+		return ERR_PTR(-ENOMEM);
+	}
+	for (i = 0; i < KVM_PARAVIRT_PERF_EVENT_ENTRY_NUM; i++)
+		INIT_LIST_HEAD(&hash_table[i]);
+	kvm->arch.shadow_hash_table = hash_table;
+	spin_lock_init(&kvm->arch.shadow_lock);
 
 	INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
 	INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
@@ -5416,6 +5442,8 @@ void kvm_arch_sync_events(struct kvm *kv
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
+	kvm_remove_all_perf_events(kvm);
+
 	kvm_iommu_unmap_guest(kvm);
 	kvm_free_pit(kvm);
 	kfree(kvm->arch.vpic);
@@ -5427,6 +5455,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm
 	if (kvm->arch.ept_identity_pagetable)
 		put_page(kvm->arch.ept_identity_pagetable);
 	cleanup_srcu_struct(&kvm->srcu);
+	kfree(kvm->arch.shadow_hash_table);
 	kfree(kvm->arch.aliases);
 	kfree(kvm);
 }
--- linux-2.6_tip0620/arch/x86/kvm/x86.h	2010-06-21 15:19:39.311999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/kvm/x86.h	2010-06-21 15:21:39.312999849 +0800
@@ -72,7 +72,20 @@ static inline struct kvm_mem_aliases *kv
 			|| lockdep_is_held(&kvm->slots_lock));
 }
 
+static inline gpa_t hc_gpa(struct kvm_vcpu *vcpu, unsigned long a0,
+			   unsigned long a1)
+{
+	if (is_long_mode(vcpu))
+		return a0;
+	else
+		return a0 | ((gpa_t)a1 << 32);
+}
+
 void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
 void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
+int kvm_notify_event_overflow(void);
+void kvm_copy_event_to_shadow(struct perf_event *event, int overflows);
+void kvm_sync_events_to_guest(struct kvm_vcpu *vcpu);
+void kvm_remove_all_perf_events(struct kvm *kvm);
 
 #endif
--- linux-2.6_tip0620/arch/x86/kvm/Makefile	2010-06-21 15:19:39.311999849 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/kvm/Makefile	2010-06-21 15:21:39.310999849 +0800
@@ -11,7 +11,7 @@ kvm-y			+= $(addprefix ../../../virt/kvm
 kvm-$(CONFIG_IOMMU_API)	+= $(addprefix ../../../virt/kvm/, iommu.o)
 
 kvm-y			+= x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
-			   i8254.o timer.o
+			   i8254.o timer.o kvmperf_event.o
 kvm-intel-y		+= vmx.o
 kvm-amd-y		+= svm.o
 
--- linux-2.6_tip0620/arch/x86/kvm/kvmperf_event.c	1970-01-01 08:00:00.000000000 +0800
+++ linux-2.6_tip0620perfkvm/arch/x86/kvm/kvmperf_event.c	2010-06-21 16:49:29.509999849 +0800
@@ -0,0 +1,471 @@
+/*
+ * Performance events x86 kvm para architecture code
+ *
+ * Copyright (C) 2010 Intel Inc.
+ *     Zhang Yanmin <yanmin.zhang@...el.com>
+ *
+ *  For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/perf_event.h>
+#include <linux/capability.h>
+#include <linux/notifier.h>
+#include <linux/hardirq.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/kdebug.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/cpu.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/file.h>
+#include <linux/syscalls.h>
+#include <linux/init.h>
+#include <linux/hash.h>
+
+#include <asm/apic.h>
+#include <asm/stacktrace.h>
+#include <asm/nmi.h>
+#include <asm/compat.h>
+
+#include "x86.h"
+
+#define KVM_MAX_PARAVIRT_PERF_EVENT		(1024)
+
+static inline u32 shadow_hash_id(int id)
+{
+	u32 hash_value = id;
+
+	hash_value = hash_32(hash_value, KVM_PARAVIRT_PERF_EVENT_ENTRY_BITS);
+	return hash_value;
+}
+
+static int kvm_add_host_event(struct kvm_vcpu *vcpu,
+		struct host_perf_shadow *host_shadow)
+{
+	long unsigned flags;
+	u32 index = shadow_hash_id(host_shadow->id);
+	struct kvm_arch *arch = &vcpu->kvm->arch;
+	struct list_head *head = &arch->shadow_hash_table[index];
+	struct list_head *pos;
+	struct host_perf_shadow *tmp;
+
+	spin_lock_irqsave(&arch->shadow_lock, flags);
+	list_for_each(pos, head) {
+		tmp = container_of(pos, struct host_perf_shadow, shadow_entry);
+		WARN(tmp->id == host_shadow->id, "%s called when there is an"
+			" item with the same id [%d] in hash table,",
+			__func__, host_shadow->id);
+	}
+	list_add(&host_shadow->shadow_entry, head);
+	spin_unlock_irqrestore(&arch->shadow_lock, flags);
+	return 0;
+}
+
+static struct perf_event *
+kvm_find_get_host_event(struct kvm_vcpu *vcpu, int id, int need_delete)
+{
+	long unsigned flags;
+	u32 index = shadow_hash_id(id);
+	struct kvm_arch *arch = &vcpu->kvm->arch;
+	struct list_head *head = &arch->shadow_hash_table[index];
+	struct list_head *pos;
+	struct host_perf_shadow *tmp = NULL;
+	int found = 0;
+
+	spin_lock_irqsave(&arch->shadow_lock, flags);
+	list_for_each(pos, head) {
+		tmp = container_of(pos, struct host_perf_shadow, shadow_entry);
+		if (tmp->id == id) {
+			found = 1;
+			if (need_delete)
+				list_del_init(&tmp->shadow_entry);
+			else
+				atomic_inc(&tmp->ref_counter);
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&arch->shadow_lock, flags);
+
+	if (found)
+		return tmp->host_event;
+	else
+		return NULL;
+}
+
+static void kvm_vcpu_add_event_overflow_ref(struct perf_event *event)
+{
+	struct host_perf_shadow *host_shadow = event->host_perf_shadow;
+	struct kvm_vcpu *vcpu = host_shadow->vcpu;
+	int ret;
+
+	/*
+	 * Use trylock as it's in NMI handler. We don't care
+	 * too much to lose reporting once of one event to guets os,
+	 * because host saves overflows counter in host_perf_shadow.
+	 * Next time when a new overflow of the event happens and if
+	 * there is no contention, host could push overflows to guest
+	 * and guest could process also saved overflows.
+	 */
+	ret = mutex_trylock(&vcpu->arch.event_mutex);
+	if (!ret)
+		return;
+	if (vcpu->arch.overflows < X86_PMC_IDX_MAX) {
+		vcpu->arch.overflow_events[vcpu->arch.overflows] = event;
+		vcpu->arch.overflows++;
+	}
+	mutex_unlock(&vcpu->arch.event_mutex);
+}
+
+static int kvm_vcpu_remove_event_overflow_ref(struct host_perf_shadow *shadow)
+{
+	struct kvm_vcpu *vcpu = shadow->vcpu;
+	int i;
+
+	if (!vcpu || !vcpu->arch.overflows)
+		return -1;
+
+	mutex_lock(&vcpu->arch.event_mutex);
+	for (i = 0; i < vcpu->arch.overflows; i++) {
+		if (vcpu->arch.overflow_events[i] == shadow->host_event)
+			vcpu->arch.overflow_events[i] = NULL;
+	}
+	mutex_unlock(&vcpu->arch.event_mutex);
+	return 0;
+}
+
+void kvm_copy_event_to_shadow(struct perf_event *event, int overflows)
+{
+	struct host_perf_shadow *shadow = event->host_perf_shadow;
+
+	shadow->counter.count = local64_read(&event->count);
+	atomic_add(overflows, &shadow->counter.overflows);
+	kvm_vcpu_add_event_overflow_ref(event);
+	/* Inject NMI to guest os */
+	kvm_notify_event_overflow();
+}
+
+static void kvm_perf_event_overflow(struct perf_event *event, int nmi,
+		struct perf_sample_data *data, struct pt_regs *regs)
+{
+	BUG_ON(event->host_perf_shadow == NULL);
+	kvm_copy_event_to_shadow(event, 1);
+}
+
+static void kvm_put_host_event(struct perf_event *host_event)
+{
+	struct host_perf_shadow *shadow = host_event->host_perf_shadow;
+	if (!atomic_dec_return(&shadow->ref_counter)) {
+		/*
+		 * detach it in case guest os doesn't disables it
+		 * before closing
+		 */
+		perf_event_detach(host_event);
+		kvm_vcpu_remove_event_overflow_ref(shadow);
+
+		perf_event_release_kernel(host_event);
+		kfree(shadow);
+		atomic_dec(&shadow->vcpu->kvm->arch.kvm_pv_event_num);
+	}
+}
+
+static void kvm_copy_event_to_guest(struct kvm_vcpu *vcpu,
+			struct perf_event *host_event)
+{
+	struct host_perf_shadow *shadow = host_event->host_perf_shadow;
+	struct guest_perf_event counter;
+	int ret;
+	s32 overflows;
+
+	ret = kvm_read_guest(vcpu->kvm, shadow->guest_event_addr,
+				&counter, sizeof(counter));
+	if (ret < 0)
+		return;
+
+again:
+	overflows = atomic_read(&shadow->counter.overflows);
+	if (atomic_cmpxchg(&shadow->counter.overflows, overflows, 0) !=
+			overflows)
+		goto again;
+
+	counter.count = shadow->counter.count;
+	atomic_add(overflows, &counter.overflows);
+
+	kvm_write_guest(vcpu->kvm,
+			shadow->guest_event_addr,
+			&counter,
+			sizeof(counter));
+	return;
+}
+
+/*
+ * called by KVM to copy both perf_event->count and overflows to guest
+ * after host NMI handler detects guest perf_event overflows
+ */
+void kvm_sync_events_to_guest(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	if (vcpu->arch.overflows == 0)
+		return;
+
+	mutex_lock(&vcpu->arch.event_mutex);
+	for (i = 0; i < vcpu->arch.overflows; i++) {
+		if (vcpu->arch.overflow_events[i]) {
+			kvm_copy_event_to_guest(vcpu,
+				vcpu->arch.overflow_events[i]);
+		}
+	}
+	vcpu->arch.overflows = 0;
+	mutex_unlock(&vcpu->arch.event_mutex);
+}
+EXPORT_SYMBOL_GPL(kvm_sync_events_to_guest);
+
+/* Just copy perf_event->count to guest. Don't copy overflows to guest */
+static void
+kvm_copy_count_to_guest(struct kvm_vcpu *vcpu, struct perf_event *host_event)
+{
+	struct host_perf_shadow *shadow = host_event->host_perf_shadow;
+
+	shadow->counter.count = local64_read(&host_event->count);
+	kvm_write_guest(vcpu->kvm,
+			shadow->guest_event_addr,
+			&shadow->counter.count,
+			sizeof(shadow->counter.count));
+	return;
+}
+
+static int
+kvm_pv_perf_op_open(struct kvm_vcpu *vcpu, gpa_t addr)
+{
+	int ret = 0;
+	struct perf_event *host_event = NULL;
+	struct host_perf_shadow *shadow = NULL;
+	struct guest_perf_event_param param;
+	struct guest_perf_attr *guest_attr = NULL;
+	struct perf_event_attr *attr = NULL;
+	int next_count;
+
+	next_count = atomic_read(&vcpu->kvm->arch.kvm_pv_event_num);
+	if (next_count >= KVM_MAX_PARAVIRT_PERF_EVENT) {
+		WARN_ONCE(1, "guest os wants to open more than %d events\n",
+			KVM_MAX_PARAVIRT_PERF_EVENT);
+		return -ENOENT;
+	}
+	atomic_inc(&vcpu->kvm->arch.kvm_pv_event_num);
+
+	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+	if (!attr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	guest_attr = kzalloc(sizeof(*guest_attr), GFP_KERNEL);
+	if (!attr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = kvm_read_guest(vcpu->kvm, addr, &param, sizeof(param));
+	if (ret < 0)
+		goto out;
+
+	host_event = kvm_find_get_host_event(vcpu, param.id, 0);
+	if (host_event) {
+		kvm_put_host_event(host_event);
+		return -EEXIST;
+	}
+
+	ret = kvm_read_guest(vcpu->kvm, param.attr_addr,
+			     guest_attr, sizeof(*guest_attr));
+	if (ret < 0)
+		goto out;
+
+	attr->type = guest_attr->type;
+	attr->config = guest_attr->config;
+	attr->sample_period = guest_attr->sample_period;
+	attr->read_format = guest_attr->read_format;
+	attr->flags = guest_attr->flags;
+	attr->bp_type = guest_attr->bp_type;
+	attr->bp_addr = guest_attr->bp_addr;
+	attr->bp_len = guest_attr->bp_len;
+	/*
+	 * By default, we disable the host event. Later on, guets os
+	 * triggers a perf_event_attach to enable it
+	 */
+	attr->disabled = 1;
+	attr->inherit = 0;
+	attr->enable_on_exec = 0;
+	/*
+	 * We don't support exclude mode of user and kernel for guest os,
+	 * which mean we always collect both user and kernel for guest os
+	 */
+	attr->exclude_user = 0;
+	attr->exclude_kernel = 0;
+
+	shadow = kzalloc(sizeof(*shadow), GFP_KERNEL);
+	if (!shadow) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	shadow->id = param.id;
+	shadow->guest_event_addr = param.guest_event_addr;
+	shadow->vcpu = vcpu;
+	INIT_LIST_HEAD(&shadow->shadow_entry);
+
+	/* We always create a cpu context host perf event */
+	host_event = perf_event_create_kernel_counter(attr, -1,
+				current->pid, kvm_perf_event_overflow);
+
+	if (IS_ERR(host_event)) {
+		host_event = NULL;
+		ret = -1;
+		goto out;
+	}
+	host_event->host_perf_shadow = shadow;
+	shadow->host_event = host_event;
+	atomic_set(&shadow->ref_counter, 1);
+	kvm_add_host_event(vcpu, shadow);
+
+out:
+	if (!host_event)
+		kfree(shadow);
+
+	kfree(attr);
+	kfree(guest_attr);
+
+	if (ret)
+		atomic_dec(&vcpu->kvm->arch.kvm_pv_event_num);
+
+	return ret;
+}
+
+static int kvm_pv_perf_op_close(struct kvm_vcpu *vcpu, int id)
+{
+	struct perf_event *host_event;
+
+	/* Find and delete the event from the hashtable */
+	host_event = kvm_find_get_host_event(vcpu, id, 1);
+	if (!host_event)
+		return -1;
+	kvm_put_host_event(host_event);
+	return 0;
+}
+
+static int kvm_pv_perf_op_enable(struct kvm_vcpu *vcpu, int id)
+{
+	struct perf_event *event;
+	struct host_perf_shadow *shadow;
+
+	event = kvm_find_get_host_event(vcpu, id, 0);
+	if (!event)
+		return -1;
+
+	shadow = event->host_perf_shadow;
+	if (shadow->vcpu != vcpu) {
+		kvm_vcpu_remove_event_overflow_ref(event->host_perf_shadow);
+		shadow->vcpu = vcpu;
+	}
+
+	perf_event_attach(event);
+	kvm_put_host_event(event);
+
+	return 0;
+}
+
+static int kvm_pv_perf_op_disable(struct kvm_vcpu *vcpu, int id)
+{
+	struct perf_event *host_event = kvm_find_get_host_event(vcpu, id, 0);
+	if (!host_event)
+		return -1;
+	perf_event_detach(host_event);
+	/* We sync count to guest as we delay the guest count update */
+	kvm_copy_count_to_guest(vcpu, host_event);
+	kvm_put_host_event(host_event);
+
+	return 0;
+}
+
+static int kvm_pv_perf_op_read(struct kvm_vcpu *vcpu, int id)
+{
+	u64 enabled, running;
+	struct perf_event *host_event = kvm_find_get_host_event(vcpu, id, 0);
+
+	if (!host_event)
+		return -1;
+	if (host_event->state == PERF_EVENT_STATE_ACTIVE)
+		perf_event_read_value(host_event, &enabled, &running);
+	kvm_copy_count_to_guest(vcpu, host_event);
+	kvm_put_host_event(host_event);
+	return 0;
+}
+
+int kvm_pv_perf_op(struct kvm_vcpu *vcpu, int op_code, unsigned long a1,
+		unsigned long a2, unsigned long *result)
+{
+	unsigned long ret;
+	gpa_t addr;
+	int id;
+
+	switch (op_code) {
+	case KVM_PERF_OP_OPEN:
+		addr = hc_gpa(vcpu, a1, a2);
+		ret = (unsigned long) kvm_pv_perf_op_open(vcpu, addr);
+		break;
+	case KVM_PERF_OP_CLOSE:
+		id = (int) a1;
+		ret = kvm_pv_perf_op_close(vcpu, id);
+		break;
+	case KVM_PERF_OP_ENABLE:
+		id = (int) a1;
+		ret = kvm_pv_perf_op_enable(vcpu, id);
+		break;
+	case KVM_PERF_OP_DISABLE:
+		id = (int) a1;
+		ret = kvm_pv_perf_op_disable(vcpu, id);
+		break;
+	case KVM_PERF_OP_READ:
+		id = (int) a1;
+		ret = kvm_pv_perf_op_read(vcpu, id);
+		break;
+	default:
+		ret = -KVM_ENOSYS;
+	}
+
+	*result = ret;
+	return 0;
+}
+
+void kvm_remove_all_perf_events(struct kvm *kvm)
+{
+	long unsigned flags;
+	struct kvm_arch *arch = &kvm->arch;
+	LIST_HEAD(total_events);
+	struct list_head *head;
+	struct list_head *pos, *next;
+	struct host_perf_shadow *tmp;
+	int i;
+
+	spin_lock_irqsave(&arch->shadow_lock, flags);
+	for (i = 0; i < KVM_PARAVIRT_PERF_EVENT_ENTRY_NUM; i++) {
+		head = &arch->shadow_hash_table[i];
+		list_for_each_safe(pos, next, head) {
+			tmp = container_of(pos, struct host_perf_shadow,
+					shadow_entry);
+			list_del(&tmp->shadow_entry);
+			list_add(&tmp->shadow_entry, &total_events);
+		}
+	}
+	spin_unlock_irqrestore(&arch->shadow_lock, flags);
+	head = &total_events;
+	list_for_each_safe(pos, next, head) {
+		tmp = container_of(pos, struct host_perf_shadow, shadow_entry);
+		list_del(&tmp->shadow_entry);
+		kvm_put_host_event(tmp->host_event);
+	}
+
+	return;
+}
+
--- linux-2.6_tip0620/include/linux/kvm.h	2010-06-21 15:19:52.605999849 +0800
+++ linux-2.6_tip0620perfkvm/include/linux/kvm.h	2010-06-21 15:21:39.312999849 +0800
@@ -524,6 +524,7 @@ struct kvm_enable_cap {
 #define KVM_CAP_PPC_OSI 52
 #define KVM_CAP_PPC_UNSET_IRQ 53
 #define KVM_CAP_ENABLE_CAP 54
+#define KVM_CAP_PV_PERF 57
 
 #ifdef KVM_CAP_IRQ_ROUTING
 


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