On 2011-02-07 14:40, Glauber Costa wrote:
> On Mon, 2011-02-07 at 13:36 +0100, Jan Kiszka wrote:
>> On 2011-02-07 13:27, Glauber Costa wrote:
>>> On Mon, 2011-02-07 at 12:19 +0100, Jan Kiszka wrote:
>>>> 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@xxxxxxxxxxx>
>>>> CC: Glauber Costa <glommer@xxxxxxxxxx>
>>>> ---
>>>> Makefile.target | 4 +-
>>>> hw/kvmclock.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>> hw/kvmclock.h | 14 ++++++
>>>> hw/pc_piix.c | 31 +++++++++++---
>>>> 4 files changed, 165 insertions(+), 9 deletions(-)
>>>> create mode 100644 hw/kvmclock.c
>>>> create mode 100644 hw/kvmclock.h
>>>>
>>>> diff --git a/Makefile.target b/Makefile.target
>>>> index b0ba95f..30232fa 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 += vmmouse.o vmport.o hpet.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@xxxxxxxxxxx>
>>>> + *
>>>> + * 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@xxxxxxxxxxx>
>>>> + *
>>>> + * 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 7b74473..9bc4659 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)
>>>>
>>> What exactly is your motivation to that ? I think mid/long-term
>>> we should be making machine initialization more common among
>>> architectures, not introducing more arch specific, or even worse, kvm
>>> specific parameters here.
>>>
>>> I'd like to understand what do we gain from that, since opting kvmclock
>>> in our out is done by cpuid anyway - no need for a specific machine.
>>
>> Is that really the case? I thought we were already shipping versions
>> where that CPU feature was enabled by default. If not, I'll happily drop
>> that admittedly clumsy approach above.
>
> Yes, AFAIK, kvmclock is enabled by default, disabled by cpuid-leaf, as
> in
> -cpu kvm64,-kvmclock
>
> So your test for cpuid bit before starting kvmclock should already cover
> it.
>
No, just the contrary: As kvmclock was always enabled in older versions
and the compat machines also expose it, we cannot rely on the flag to
enable this new (and therefore 0.15-only) vmstate.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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