From: Vitaly Kuznetsov <vkuzn...@redhat.com>
QEMU's kvmclock device is only created when KVM PV feature bits for
kvmclock (KVM_FEATURE_CLOCKSOURCE/KVM_FEATURE_CLOCKSOURCE2) are
exposed to the guest. With 'kvm=off' cpu flag the device is not
created and we don't call KVM_GET_CLOCK/KVM_SET_CLOCK upon migration.
It was reported that without these call at least Hyper-V TSC page
clocksouce (which can be enabled independently) gets broken after
migration.
Switch to creating kvmclock QEMU device unconditionally, it seems
to always make sense to call KVM_GET_CLOCK/KVM_SET_CLOCK on migration.
Use KVM_CAP_ADJUST_CLOCK check instead of CPUID feature bits.
Reported-by: Antoine Damhet <antoine.dam...@blade-group.com>
Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Message-Id: <20200922151934.899555-1-vkuzn...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/i386/kvm/clock.c | 7 +++++--
hw/i386/microvm.c | 2 +-
hw/i386/pc.c | 1 +
hw/i386/pc_piix.c | 7 +++++--
hw/i386/pc_q35.c | 5 ++++-
include/hw/i386/pc.h | 3 +++
include/hw/kvm/clock.h | 4 ++--
target/i386/kvm.c | 5 +++++
target/i386/kvm_i386.h | 1 +
9 files changed, 27 insertions(+), 8 deletions(-)
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 7b296ae192..24fe5091b6 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -329,11 +329,14 @@ static const TypeInfo kvmclock_info = {
};
/* Note: Must be called after VCPU initialization. */
-void kvmclock_create(void)
+void kvmclock_create(bool create_always)
{
X86CPU *cpu = X86_CPU(first_cpu);
- if (kvm_enabled() &&
+ if (!kvm_enabled() || !kvm_has_adjust_clock())
+ return;
+
+ if (create_always ||
cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
(1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
index 60d3272230..aedcae3426 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -125,7 +125,7 @@ static void microvm_devices_init(MicrovmMachineState *mms)
ioapic_init_gsi(gsi_state, "machine");
- kvmclock_create();
+ kvmclock_create(true);
mms->virtio_irq_base = x86_machine_is_acpi_enabled(x86ms) ? 16 : 5;
for (i = 0; i < VIRTIO_NUM_TRANSPORTS; i++) {
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 50e8317342..da2ebc3fa0 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1655,6 +1655,7 @@ static void pc_machine_class_init(ObjectClass *oc, void
*data)
pcmc->acpi_data_size = 0x20000 + 0x8000;
pcmc->linuxboot_dma_enabled = true;
pcmc->pvh_enabled = true;
+ pcmc->kvmclock_create_always = true;
assert(!mc->get_hotplug_handler);
mc->get_hotplug_handler = pc_get_hotplug_handler;
mc->hotplug_allowed = pc_hotplug_allowed;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 7d5aa6d1ba..3c2ae0612b 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -158,8 +158,8 @@ static void pc_init1(MachineState *machine,
x86_cpus_init(x86ms, pcmc->default_cpu_version);
- if (kvm_enabled() && pcmc->kvmclock_enabled) {
- kvmclock_create();
+ if (pcmc->kvmclock_enabled) {
+ kvmclock_create(pcmc->kvmclock_create_always);
}
if (pcmc->pci_enabled) {
@@ -440,11 +440,14 @@ DEFINE_I440FX_MACHINE(v5_2, "pc-i440fx-5.2", NULL,
static void pc_i440fx_5_1_machine_options(MachineClass *m)
{
+ PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
+
pc_i440fx_5_2_machine_options(m);
m->alias = NULL;
m->is_default = false;
compat_props_add(m->compat_props, hw_compat_5_1, hw_compat_5_1_len);
compat_props_add(m->compat_props, pc_compat_5_1, pc_compat_5_1_len);
+ pcmc->kvmclock_create_always = false;
}
DEFINE_I440FX_MACHINE(v5_1, "pc-i440fx-5.1", NULL,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index a4a37b26c5..b885c93aef 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -179,7 +179,7 @@ static void pc_q35_init(MachineState *machine)
x86_cpus_init(x86ms, pcmc->default_cpu_version);
- kvmclock_create();
+ kvmclock_create(pcmc->kvmclock_create_always);
/* pci enabled */
if (pcmc->pci_enabled) {
@@ -357,10 +357,13 @@ DEFINE_Q35_MACHINE(v5_2, "pc-q35-5.2", NULL,
static void pc_q35_5_1_machine_options(MachineClass *m)
{
+ PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
+
pc_q35_5_2_machine_options(m);
m->alias = NULL;
compat_props_add(m->compat_props, hw_compat_5_1, hw_compat_5_1_len);
compat_props_add(m->compat_props, pc_compat_5_1, pc_compat_5_1_len);
+ pcmc->kvmclock_create_always = false;
}
DEFINE_Q35_MACHINE(v5_1, "pc-q35-5.1", NULL,
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 8699029053..84639d0ebc 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -118,6 +118,9 @@ struct PCMachineClass {
/* use PVH to load kernels that support this feature */
bool pvh_enabled;
+
+ /* create kvmclock device even when KVM PV features are not exposed */
+ bool kvmclock_create_always;
};
#define TYPE_PC_MACHINE "generic-pc-machine"
diff --git a/include/hw/kvm/clock.h b/include/hw/kvm/clock.h
index 81c66b2302..7994071c4f 100644
--- a/include/hw/kvm/clock.h
+++ b/include/hw/kvm/clock.h
@@ -15,11 +15,11 @@
#ifdef CONFIG_KVM
-void kvmclock_create(void);
+void kvmclock_create(bool create_always);
#else /* CONFIG_KVM */
-static inline void kvmclock_create(void)
+static inline void kvmclock_create(bool create_always)
{
}
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index b327e8706f..4fc6e8b9d5 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -143,6 +143,11 @@ bool kvm_has_adjust_clock_stable(void)
return (ret == KVM_CLOCK_TSC_STABLE);
}
+bool kvm_has_adjust_clock(void)
+{
+ return kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
+}
+
bool kvm_has_exception_payload(void)
{
return has_exception_payload;
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 064b8798a2..0fce4e51d2 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -34,6 +34,7 @@
bool kvm_allows_irq0_override(void);
bool kvm_has_smm(void);
+bool kvm_has_adjust_clock(void);
bool kvm_has_adjust_clock_stable(void);
bool kvm_has_exception_payload(void);
void kvm_synchronize_all_tsc(void);
--
2.26.2
