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[PATCH v2] target/i386: always create kvmclock device
From: |
Vitaly Kuznetsov |
Subject: |
[PATCH v2] target/i386: always create kvmclock device |
Date: |
Tue, 22 Sep 2020 17:19:34 +0200 |
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.damhet@blade-group.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@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 64283358f91d..30cf53393ee1 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -328,11 +328,14 @@ 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 81d0888930d1..fd0b84109154 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -119,7 +119,7 @@ static void microvm_devices_init(MicrovmMachineState *mms)
ioapic_init_gsi(gsi_state, "machine");
- kvmclock_create();
+ kvmclock_create(true);
for (i = 0; i < VIRTIO_NUM_TRANSPORTS; i++) {
sysbus_create_simple("virtio-mmio",
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index d11daacc23cf..0e036ef9c15f 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1956,6 +1956,7 @@ 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 32b1453e6a82..1a68338c737b 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 0cb9c18cd44d..0dd59bd765b1 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -185,7 +185,7 @@ 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) {
@@ -366,10 +366,13 @@ 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 fe52e165b27c..6b22671434b9 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -118,6 +118,9 @@ typedef 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;
} PCMachineClass;
#define TYPE_PC_MACHINE "generic-pc-machine"
diff --git a/include/hw/kvm/clock.h b/include/hw/kvm/clock.h
index 81c66b230207..7994071c4fee 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 4a8b3a41c1bc..20b31b65307b 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 064b8798a26c..0fce4e51d2d6 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);
--
2.25.4
- [PATCH v2] target/i386: always create kvmclock device,
Vitaly Kuznetsov <=