[PATCH 37/37] kvm: x86: Introduce kvmclock device to save/restore its state

Marcelo Tosatti
2011-02-14T15:25:12Z

If kvmclock is used, which implies the kernel supports it, register a
kvmclock device with the sysbus. Its main purpose is to save and restore
the kernel state on migration, but this will also allow to visualize it
one day.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
CC: Glauber Costa <glommer@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
Makefile.target | 4 +-
hw/kvmclock.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
hw/kvmclock.h | 14 ++++++
hw/pc_piix.c | 32 +++++++++++---
4 files changed, 166 insertions(+), 9 deletions(-)
create mode 100644 hw/kvmclock.c
create mode 100644 hw/kvmclock.h

diff --git a/Makefile.target b/Makefile.target
index a6c30dd..5a0fd40 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -37,7 +37,7 @@ ifndef CONFIG_HAIKU
LIBS+=-lm
endif

-kvm.o kvm-all.o vhost.o vhost_net.o: QEMU_CFLAGS+=$(KVM_CFLAGS)
+kvm.o kvm-all.o vhost.o vhost_net.o kvmclock.o: QEMU_CFLAGS+=$(KVM_CFLAGS)

config-target.h: config-target.h-timestamp
config-target.h-timestamp: config-target.mak
@@ -218,7 +218,7 @@ obj-i386-y += cirrus_vga.o apic.o ioapic.o piix_pci.o
obj-i386-y += vmport.o applesmc.o
obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
obj-i386-y += debugcon.o multiboot.o
-obj-i386-y += pc_piix.o
+obj-i386-y += pc_piix.o kvmclock.o
obj-i386-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o

# shared objects
diff --git a/hw/kvmclock.c b/hw/kvmclock.c
new file mode 100644
index 0000000..b6ceddf
--- /dev/null
+++ b/hw/kvmclock.c
@@ -0,0 +1,125 @@
+/*
+ * QEMU KVM support, paravirtual clock device
+ *
+ * Copyright (C) 2011 Siemens AG
+ *
+ * Authors:
+ * Jan Kiszka <jan.kiszka@siemens.com>
+ *
+ * This work is licensed under the terms of the GNU GPL version 2.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "sysemu.h"
+#include "sysbus.h"
+#include "kvm.h"
+#include "kvmclock.h"
+
+#if defined(CONFIG_KVM_PARA) && defined(KVM_CAP_ADJUST_CLOCK)
+
+#include <linux/kvm.h>
+#include <linux/kvm_para.h>
+
+typedef struct KVMClockState {
+ SysBusDevice busdev;
+ uint64_t clock;
+ bool clock_valid;
+} KVMClockState;
+
+static void kvmclock_pre_save(void *opaque)
+{
+ KVMClockState *s = opaque;
+ struct kvm_clock_data data;
+ int ret;
+
+ if (s->clock_valid) {
+ return;
+ }
+ ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
+ if (ret < 0) {
+ fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
+ data.clock = 0;
+ }
+ s->clock = data.clock;
+ /*
+ * If the VM is stopped, declare the clock state valid to avoid re-reading
+ * it on next vmsave (which would return a different value). Will be reset
+ * when the VM is continued.
+ */
+ s->clock_valid = !vm_running;
+}
+
+static int kvmclock_post_load(void *opaque, int version_id)
+{
+ KVMClockState *s = opaque;
+ struct kvm_clock_data data;
+
+ data.clock = s->clock;
+ data.flags = 0;
+ return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
+}
+
+static void kvmclock_vm_state_change(void *opaque, int running, int reason)
+{
+ KVMClockState *s = opaque;
+
+ if (running) {
+ s->clock_valid = false;
+ }
+}
+
+static int kvmclock_init(SysBusDevice *dev)
+{
+ KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
+
+ qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
+ return 0;
+}
+
+static const VMStateDescription kvmclock_vmsd = {
+ .name = "kvmclock",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .minimum_version_id_old = 1,
+ .pre_save = kvmclock_pre_save,
+ .post_load = kvmclock_post_load,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT64(clock, KVMClockState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static SysBusDeviceInfo kvmclock_info = {
+ .qdev.name = "kvmclock",
+ .qdev.size = sizeof(KVMClockState),
+ .qdev.vmsd = &kvmclock_vmsd,
+ .qdev.no_user = 1,
+ .init = kvmclock_init,
+};
+
+/* Note: Must be called after VCPU initialization. */
+void kvmclock_create(void)
+{
+ if (kvm_enabled() &&
+ first_cpu->cpuid_kvm_features & (1ULL << KVM_FEATURE_CLOCKSOURCE)) {
+ sysbus_create_simple("kvmclock", -1, NULL);
+ }
+}
+
+static void kvmclock_register_device(void)
+{
+ if (kvm_enabled()) {
+ sysbus_register_withprop(&kvmclock_info);
+ }
+}
+
+device_init(kvmclock_register_device);
+
+#else /* !(CONFIG_KVM_PARA && KVM_CAP_ADJUST_CLOCK) */
+
+void kvmclock_create(void)
+{
+}
+#endif /* !(CONFIG_KVM_PARA && KVM_CAP_ADJUST_CLOCK) */
diff --git a/hw/kvmclock.h b/hw/kvmclock.h
new file mode 100644
index 0000000..7a83cbe
--- /dev/null
+++ b/hw/kvmclock.h
@@ -0,0 +1,14 @@
+/*
+ * QEMU KVM support, paravirtual clock device
+ *
+ * Copyright (C) 2011 Siemens AG
+ *
+ * Authors:
+ * Jan Kiszka <jan.kiszka@siemens.com>
+ *
+ * This work is licensed under the terms of the GNU GPL version 2.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+void kvmclock_create(void);
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index d0bd0cd..2918454 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -32,6 +32,7 @@
#include "boards.h"
#include "ide.h"
#include "kvm.h"
+#include "kvmclock.h"
#include "sysemu.h"
#include "sysbus.h"
#include "arch_init.h"
@@ -66,7 +67,8 @@ static void pc_init1(ram_addr_t ram_size,
const char *kernel_cmdline,
const char *initrd_filename,
const char *cpu_model,
- int pci_enabled)
+ int pci_enabled,
+ int kvmclock_enabled)
{
int i;
ram_addr_t below_4g_mem_size, above_4g_mem_size;
@@ -86,6 +88,10 @@ static void pc_init1(ram_addr_t ram_size,

pc_cpus_init(cpu_model);

+ if (kvmclock_enabled) {
+ kvmclock_create();
+ }
+
/* allocate ram and load rom/bios */
pc_memory_init(ram_size, kernel_filename, kernel_cmdline, initrd_filename,
&below_4g_mem_size, &above_4g_mem_size);
@@ -193,7 +199,19 @@ static void pc_init_pci(ram_addr_t ram_size,
{
pc_init1(ram_size, boot_device,
kernel_filename, kernel_cmdline,
- initrd_filename, cpu_model, 1);
+ initrd_filename, cpu_model, 1, 1);
+}
+
+static void pc_init_pci_no_kvmclock(ram_addr_t ram_size,
+ const char *boot_device,
+ const char *kernel_filename,
+ const char *kernel_cmdline,
+ const char *initrd_filename,
+ const char *cpu_model)
+{
+ pc_init1(ram_size, boot_device,
+ kernel_filename, kernel_cmdline,
+ initrd_filename, cpu_model, 1, 0);
}

static void pc_init_isa(ram_addr_t ram_size,
@@ -207,7 +225,7 @@ static void pc_init_isa(ram_addr_t ram_size,
cpu_model = "486";
pc_init1(ram_size, boot_device,
kernel_filename, kernel_cmdline,
- initrd_filename, cpu_model, 0);
+ initrd_filename, cpu_model, 0, 1);
}

static QEMUMachine pc_machine = {
@@ -222,7 +240,7 @@ static QEMUMachine pc_machine = {
static QEMUMachine pc_machine_v0_13 = {
.name = "pc-0.13",
.desc = "Standard PC",
- .init = pc_init_pci,
+ .init = pc_init_pci_no_kvmclock,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
{
@@ -249,7 +267,7 @@ static QEMUMachine pc_machine_v0_13 = {
static QEMUMachine pc_machine_v0_12 = {
.name = "pc-0.12",
.desc = "Standard PC",
- .init = pc_init_pci,
+ .init = pc_init_pci_no_kvmclock,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
{
@@ -280,7 +298,7 @@ static QEMUMachine pc_machine_v0_12 = {
static QEMUMachine pc_machine_v0_11 = {
.name = "pc-0.11",
.desc = "Standard PC, qemu 0.11",
- .init = pc_init_pci,
+ .init = pc_init_pci_no_kvmclock,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
{
@@ -319,7 +337,7 @@ static QEMUMachine pc_machine_v0_11 = {
static QEMUMachine pc_machine_v0_10 = {
.name = "pc-0.10",
.desc = "Standard PC, qemu 0.10",
- .init = pc_init_pci,
+ .init = pc_init_pci_no_kvmclock,
.max_cpus = 255,
.compat_props = (GlobalProperty[]) {
{
--
1.7.4