[PATCH/RFC 4/4]Modify KVM to use the "account modifiers"

Laurent Vivier
2007-08-16T15:59:44Z

[-- Attachment #1: Type: text/plain, Size: 339 bytes --]

[PATCH 4/4] Modify KVM to use the "account modifiers". KVM can now measure time
consumed by a Virtual Machine on a per-cpu basis and modify kernel statistics to
report this value.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
--
------------- Laurent.Vivier@bull.net --------------
"Software is hard" - Donald Knuth

[-- Attachment #2: kvm_accounting_modifiers --]
[-- Type: text/plain, Size: 5907 bytes --]

Index: kvm/drivers/kvm/kvm.h
===================================================================
--- kvm.orig/drivers/kvm/kvm.h 2007-08-16 16:21:42.000000000 +0200
+++ kvm/drivers/kvm/kvm.h 2007-08-16 16:27:00.000000000 +0200
@@ -408,6 +408,10 @@
struct file *filp;
struct kvm_io_bus mmio_bus;
struct kvm_io_bus pio_bus;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ struct account_modifier account_modifier;
+ ktime_t vtime[NR_CPUS];
+#endif
};

struct descriptor_table {
@@ -589,6 +593,20 @@

int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);

+#ifdef CONFIG_ACCOUNT_MODIFIERS
+static inline ktime_t kvm_guest_enter(void)
+{
+ return ktime_get();
+}
+
+static inline void kvm_guest_exit(struct kvm *kvm, ktime_t enter)
+{
+ ktime_t delta = ktime_sub(ktime_get(), enter);
+ kvm->vtime[smp_processor_id()] =
+ ktime_add(kvm->vtime[smp_processor_id()], delta);
+}
+#endif
+
static inline int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
u32 error_code)
{
Index: kvm/drivers/kvm/kvm_main.c
===================================================================
--- kvm.orig/drivers/kvm/kvm_main.c 2007-08-16 16:21:42.000000000 +0200
+++ kvm/drivers/kvm/kvm_main.c 2007-08-16 16:40:28.000000000 +0200
@@ -33,6 +33,7 @@
#include <linux/file.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
+#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
@@ -57,6 +58,9 @@
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

static __read_mostly struct preempt_ops kvm_preempt_ops;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+static __read_mostly struct account_ops kvm_account_ops;
+#endif

#define STAT_OFFSET(x) offsetof(struct kvm_vcpu, stat.x)

@@ -285,6 +289,42 @@
}
EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);

+#ifdef CONFIG_ACCOUNT_MODIFIERS
+static inline
+struct kvm *account_modifier_to_kvm(struct account_modifier *am)
+{
+ return container_of(am, struct kvm, account_modifier);
+}
+
+static cputime_t kvm_account_system_modifier(struct account_modifier *modifier,
+ struct task_struct *curr,
+ int hardirq_offset,
+ cputime_t cputime)
+{
+ struct kvm *kvm = account_modifier_to_kvm(modifier);
+ ktime_t kmsec = ktime_set(0, NSEC_PER_MSEC);
+ cputime_t cmsec = msecs_to_cputime(1);
+ ktime_t vtime = kvm->vtime[smp_processor_id()];
+
+ while ((ktime_to_ns(vtime) >= NSEC_PER_MSEC) &&
+ (cputime_to_msecs(cputime) >= 1)) {
+ kvm->vtime[smp_processor_id()] = ktime_sub(vtime, kmsec);
+
+ curr->utime = cputime_add(curr->utime, cmsec);
+ curr->gtime = cputime_add(curr->gtime, cmsec);
+
+ kstat_this_cpu.cpustat.guest = cputime64_add(kstat_this_cpu.cpustat.guest,
+ cputime_to_cputime64(cmsec));
+ kstat_this_cpu.cpustat.user = cputime64_add(kstat_this_cpu.cpustat.user,
+ cputime_to_cputime64(cmsec));
+
+ cputime = cputime_sub(cputime, cmsec);
+ }
+
+ return cputime;
+}
+#endif
+
static struct kvm *kvm_create_vm(void)
{
struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
@@ -299,6 +339,15 @@
spin_lock(&kvm_lock);
list_add(&kvm->vm_list, &vm_list);
spin_unlock(&kvm_lock);
+
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ kvm_account_ops.user_time = NULL;
+ kvm_account_ops.system_time = kvm_account_system_modifier;
+
+ account_modifier_init(&kvm->account_modifier, &kvm_account_ops);
+ account_modifier_register(&kvm->account_modifier);
+#endif
+
return kvm;
}

@@ -376,6 +425,9 @@
spin_lock(&kvm_lock);
list_del(&kvm->vm_list);
spin_unlock(&kvm_lock);
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ account_modifier_unregister(&kvm->account_modifier);
+#endif
kvm_io_bus_destroy(&kvm->pio_bus);
kvm_io_bus_destroy(&kvm->mmio_bus);
kvm_free_vcpus(kvm);
Index: kvm/drivers/kvm/svm.c
===================================================================
--- kvm.orig/drivers/kvm/svm.c 2007-08-16 16:21:42.000000000 +0200
+++ kvm/drivers/kvm/svm.c 2007-08-16 16:29:41.000000000 +0200
@@ -1392,6 +1392,9 @@
u16 gs_selector;
u16 ldt_selector;
int r;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ ktime_t now;
+#endif

again:
r = kvm_mmu_reload(vcpu);
@@ -1404,6 +1407,9 @@
clgi();

vcpu->guest_mode = 1;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ now = kvm_guest_enter();
+#endif
if (vcpu->requests)
if (test_and_clear_bit(KVM_TLB_FLUSH, &vcpu->requests))
svm_flush_tlb(vcpu);
@@ -1536,6 +1542,9 @@
#endif
: "cc", "memory" );

+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ kvm_guest_exit(vcpu->kvm, now);
+#endif
vcpu->guest_mode = 0;

if (vcpu->fpu_active) {
Index: kvm/drivers/kvm/vmx.c
===================================================================
--- kvm.orig/drivers/kvm/vmx.c 2007-08-16 16:21:42.000000000 +0200
+++ kvm/drivers/kvm/vmx.c 2007-08-16 16:30:24.000000000 +0200
@@ -2052,6 +2052,9 @@
struct vcpu_vmx *vmx = to_vmx(vcpu);
u8 fail;
int r;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ ktime_t now;
+#endif

preempted:
if (vcpu->guest_debug.enabled)
@@ -2078,6 +2081,9 @@
local_irq_disable();

vcpu->guest_mode = 1;
+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ now = kvm_guest_enter();
+#endif
if (vcpu->requests)
if (test_and_clear_bit(KVM_TLB_FLUSH, &vcpu->requests))
vmx_flush_tlb(vcpu);
@@ -2198,6 +2204,9 @@
[cr2]"i"(offsetof(struct kvm_vcpu, cr2))
: "cc", "memory" );

+#ifdef CONFIG_ACCOUNT_MODIFIERS
+ kvm_guest_exit(vcpu->kvm, now);
+#endif
vcpu->guest_mode = 0;
local_irq_enable();

Index: kvm/drivers/kvm/Kconfig
===================================================================
--- kvm.orig/drivers/kvm/Kconfig 2007-08-16 16:21:42.000000000 +0200
+++ kvm/drivers/kvm/Kconfig 2007-08-16 16:21:44.000000000 +0200
@@ -41,4 +41,10 @@
Provides support for KVM on AMD processors equipped with the AMD-V
(SVM) extensions.

+config ACCOUNT_MODIFIERS
+ bool "Virtual Machine accounting support"
+ depends on KVM
+ ---help---
+ Allows to account CPU time used by the Virtual Machines.
+
endif # VIRTUALIZATION