Date:	Fri, 16 Apr 2010 15:34:35 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	Avi Kivity <avi@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Sheng Yang <sheng@...ux.intel.com>,
	Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	oerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
	Jes Sorensen <Jes.Sorensen@...hat.com>,
	linux-kernel@...r.kernel.org, Zachary Amsden <zamsden@...hat.com>,
	Gleb Natapov <gleb@...hat.com>, tim.c.chen@...el.com,
	zhiteng.huang@...el.com,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: [PATCH V4 1/2] perf & kvm: Enhance perf to collect KVM guest os
 statistics from host side

Below is the kernel patch to enable perf to collect guest os statistics.

Joerg,

Would you like to add support on svm? I don't know the exact point to trigger
NMI to host with svm.

See below code with vmx:
 
+		kvm_before_handle_nmi(&vmx->vcpu);
 		asm("int $2");
+		kvm_after_handle_nmi(&vmx->vcpu);

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

---

diff -Nraup --exclude=tools linux-2.6_tip0413/arch/x86/include/asm/perf_event.h linux-2.6_tip0413_perfkvm/arch/x86/include/asm/perf_event.h
--- linux-2.6_tip0413/arch/x86/include/asm/perf_event.h	2010-04-14 11:11:03.992966568 +0800
+++ linux-2.6_tip0413_perfkvm/arch/x86/include/asm/perf_event.h	2010-04-14 11:13:17.261881591 +0800
@@ -135,17 +135,10 @@ extern void perf_events_lapic_init(void)
  */
 #define PERF_EFLAGS_EXACT	(1UL << 3)
 
-#define perf_misc_flags(regs)				\
-({	int misc = 0;					\
-	if (user_mode(regs))				\
-		misc |= PERF_RECORD_MISC_USER;		\
-	else						\
-		misc |= PERF_RECORD_MISC_KERNEL;	\
-	if (regs->flags & PERF_EFLAGS_EXACT)		\
-		misc |= PERF_RECORD_MISC_EXACT;		\
-	misc; })
-
-#define perf_instruction_pointer(regs)	((regs)->ip)
+struct pt_regs;
+extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
+extern unsigned long perf_misc_flags(struct pt_regs *regs);
+#define perf_misc_flags(regs)	perf_misc_flags(regs)
 
 #else
 static inline void init_hw_perf_events(void)		{ }
diff -Nraup --exclude=tools linux-2.6_tip0413/arch/x86/kernel/cpu/perf_event.c linux-2.6_tip0413_perfkvm/arch/x86/kernel/cpu/perf_event.c
--- linux-2.6_tip0413/arch/x86/kernel/cpu/perf_event.c	2010-04-14 11:11:04.825028810 +0800
+++ linux-2.6_tip0413_perfkvm/arch/x86/kernel/cpu/perf_event.c	2010-04-14 17:02:12.198063684 +0800
@@ -1720,6 +1720,11 @@ struct perf_callchain_entry *perf_callch
 {
 	struct perf_callchain_entry *entry;
 
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+		/* TODO: We don't support guest os callchain now */
+		return NULL;
+	}
+
 	if (in_nmi())
 		entry = &__get_cpu_var(pmc_nmi_entry);
 	else
@@ -1743,3 +1748,30 @@ void perf_arch_fetch_caller_regs(struct 
 	regs->cs = __KERNEL_CS;
 	local_save_flags(regs->flags);
 }
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	unsigned long ip;
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+		ip = perf_guest_cbs->get_guest_ip();
+	else
+		ip = instruction_pointer(regs);
+	return ip;
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	int misc = 0;
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+		misc |= perf_guest_cbs->is_user_mode() ?
+			PERF_RECORD_MISC_GUEST_USER :
+			PERF_RECORD_MISC_GUEST_KERNEL;
+	} else
+		misc |= user_mode(regs) ? PERF_RECORD_MISC_USER :
+			PERF_RECORD_MISC_KERNEL;
+	if (regs->flags & PERF_EFLAGS_EXACT)
+		misc |= PERF_RECORD_MISC_EXACT;
+
+	return misc;
+}
+
diff -Nraup --exclude=tools linux-2.6_tip0413/arch/x86/kvm/vmx.c linux-2.6_tip0413_perfkvm/arch/x86/kvm/vmx.c
--- linux-2.6_tip0413/arch/x86/kvm/vmx.c	2010-04-14 11:11:04.353024541 +0800
+++ linux-2.6_tip0413_perfkvm/arch/x86/kvm/vmx.c	2010-04-15 10:28:39.516891050 +0800
@@ -3654,8 +3654,11 @@ static void vmx_complete_interrupts(stru
 
 	/* We need to handle NMIs before interrupts are enabled */
 	if ((exit_intr_info & INTR_INFO_INTR_TYPE_MASK) == INTR_TYPE_NMI_INTR &&
-	    (exit_intr_info & INTR_INFO_VALID_MASK))
+	    (exit_intr_info & INTR_INFO_VALID_MASK)) {
+		kvm_before_handle_nmi(&vmx->vcpu);
 		asm("int $2");
+		kvm_after_handle_nmi(&vmx->vcpu);
+	}
 
 	idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
 
diff -Nraup --exclude=tools linux-2.6_tip0413/arch/x86/kvm/x86.c linux-2.6_tip0413_perfkvm/arch/x86/kvm/x86.c
--- linux-2.6_tip0413/arch/x86/kvm/x86.c	2010-04-14 11:11:04.341042024 +0800
+++ linux-2.6_tip0413_perfkvm/arch/x86/kvm/x86.c	2010-04-15 17:16:41.340064784 +0800
@@ -40,6 +40,7 @@
 #include <linux/user-return-notifier.h>
 #include <linux/srcu.h>
 #include <linux/slab.h>
+#include <linux/perf_event.h>
 #include <trace/events/kvm.h>
 #undef TRACE_INCLUDE_FILE
 #define CREATE_TRACE_POINTS
@@ -3765,6 +3766,47 @@ static void kvm_timer_init(void)
 	}
 }
 
+static DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
+
+static int kvm_is_in_guest(void)
+{
+	return percpu_read(current_vcpu) != NULL;
+}
+
+static int kvm_is_user_mode(void)
+{
+	int user_mode = 3;
+	if (percpu_read(current_vcpu))
+		user_mode = kvm_x86_ops->get_cpl(percpu_read(current_vcpu));
+	return user_mode != 0;
+}
+
+static unsigned long kvm_get_guest_ip(void)
+{
+	unsigned long ip = 0;
+	if (percpu_read(current_vcpu))
+		ip = kvm_rip_read(percpu_read(current_vcpu));
+	return ip;
+}
+
+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,
+};
+
+void kvm_before_handle_nmi(struct kvm_vcpu *vcpu)
+{
+	percpu_write(current_vcpu, vcpu);
+}
+EXPORT_SYMBOL_GPL(kvm_before_handle_nmi);
+
+void kvm_after_handle_nmi(struct kvm_vcpu *vcpu)
+{
+	percpu_write(current_vcpu, NULL);
+}
+EXPORT_SYMBOL_GPL(kvm_after_handle_nmi);
+
 int kvm_arch_init(void *opaque)
 {
 	int r;
@@ -3801,6 +3843,8 @@ int kvm_arch_init(void *opaque)
 
 	kvm_timer_init();
 
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+
 	return 0;
 
 out:
@@ -3809,6 +3853,8 @@ out:
 
 void kvm_arch_exit(void)
 {
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
 		cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
 					    CPUFREQ_TRANSITION_NOTIFIER);
diff -Nraup --exclude=tools linux-2.6_tip0413/arch/x86/kvm/x86.h linux-2.6_tip0413_perfkvm/arch/x86/kvm/x86.h
--- linux-2.6_tip0413/arch/x86/kvm/x86.h	2010-04-14 11:11:04.328996790 +0800
+++ linux-2.6_tip0413_perfkvm/arch/x86/kvm/x86.h	2010-04-15 10:27:57.116972433 +0800
@@ -65,4 +65,7 @@ static inline int is_paging(struct kvm_v
 	return kvm_read_cr0_bits(vcpu, X86_CR0_PG);
 }
 
+void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
+void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
+
 #endif
diff -Nraup --exclude=tools linux-2.6_tip0413/include/linux/perf_event.h linux-2.6_tip0413_perfkvm/include/linux/perf_event.h
--- linux-2.6_tip0413/include/linux/perf_event.h	2010-04-14 11:11:16.922212684 +0800
+++ linux-2.6_tip0413_perfkvm/include/linux/perf_event.h	2010-04-14 11:34:33.478072738 +0800
@@ -288,11 +288,13 @@ struct perf_event_mmap_page {
 	__u64	data_tail;		/* user-space written tail */
 };
 
-#define PERF_RECORD_MISC_CPUMODE_MASK		(3 << 0)
+#define PERF_RECORD_MISC_CPUMODE_MASK		(7 << 0)
 #define PERF_RECORD_MISC_CPUMODE_UNKNOWN	(0 << 0)
 #define PERF_RECORD_MISC_KERNEL			(1 << 0)
 #define PERF_RECORD_MISC_USER			(2 << 0)
 #define PERF_RECORD_MISC_HYPERVISOR		(3 << 0)
+#define PERF_RECORD_MISC_GUEST_KERNEL		(4 << 0)
+#define PERF_RECORD_MISC_GUEST_USER		(5 << 0)
 
 #define PERF_RECORD_MISC_EXACT			(1 << 14)
 /*
@@ -446,6 +448,12 @@ enum perf_callchain_context {
 # include <asm/perf_event.h>
 #endif
 
+struct perf_guest_info_callbacks {
+	int (*is_in_guest) (void);
+	int (*is_user_mode) (void);
+	unsigned long (*get_guest_ip) (void);
+};
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 #include <asm/hw_breakpoint.h>
 #endif
@@ -920,6 +928,12 @@ static inline void perf_event_mmap(struc
 		__perf_event_mmap(vma);
 }
 
+extern struct perf_guest_info_callbacks *perf_guest_cbs;
+extern int perf_register_guest_info_callbacks(
+		struct perf_guest_info_callbacks *);
+extern int perf_unregister_guest_info_callbacks(
+		struct perf_guest_info_callbacks *);
+
 extern void perf_event_comm(struct task_struct *tsk);
 extern void perf_event_fork(struct task_struct *tsk);
 
@@ -989,6 +1003,11 @@ perf_sw_event(u32 event_id, u64 nr, int 
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
+static inline int perf_register_guest_info_callbacks
+(struct perf_guest_info_callbacks *) {return 0; }
+static inline int perf_unregister_guest_info_callbacks
+(struct perf_guest_info_callbacks *) {return 0; }
+
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 static inline void perf_event_comm(struct task_struct *tsk)		{ }
 static inline void perf_event_fork(struct task_struct *tsk)		{ }
diff -Nraup --exclude=tools linux-2.6_tip0413/kernel/perf_event.c linux-2.6_tip0413_perfkvm/kernel/perf_event.c
--- linux-2.6_tip0413/kernel/perf_event.c	2010-04-14 11:12:04.090770764 +0800
+++ linux-2.6_tip0413_perfkvm/kernel/perf_event.c	2010-04-14 11:13:17.265859229 +0800
@@ -2797,6 +2797,27 @@ void perf_arch_fetch_caller_regs(struct 
 
 
 /*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	perf_guest_cbs = cbs;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	perf_guest_cbs = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+/*
  * Output
  */
 static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail,
@@ -3748,7 +3769,7 @@ void __perf_event_mmap(struct vm_area_st
 		.event_id  = {
 			.header = {
 				.type = PERF_RECORD_MMAP,
-				.misc = 0,
+				.misc = PERF_RECORD_MISC_USER,
 				/* .size */
 			},
 			/* .pid */


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