When we stop a VM for more than 30 seconds and then resume it, by qemu
monitor command "stop" and "cont", Linux on VM will complain of "soft
lockup - CPU#x stuck for xxs!" as below:
[ 2783.809517] watchdog: BUG: soft lockup - CPU#3 stuck for 2395s!
[ 2783.809559] watchdog: BUG: soft lockup - CPU#2 stuck for 2395s!
[ 2783.809561] watchdog: BUG: soft lockup - CPU#1 stuck for 2395s!
[ 2783.809563] Modules linked in...
This is because Guest Linux uses generic timer virtual counter as
a software watchdog, and CNTVCT_EL0 does not stop when VM is stopped
by qemu.
This patch is to fix this issue by saving the value of CNTVCT_EL0 when
stopping and restoring it when resuming.
Cc: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Heyi Guo <guoh...@huawei.com>
---
target/arm/kvm.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 79a79f0..73b9ecb 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -39,11 +39,77 @@ static bool cap_has_inject_serror_esr;
static ARMHostCPUFeatures arm_host_cpu_features;
+static int get_vcpu_timer_tick(CPUState *cs, uint64_t *tick_at_pause)
+{
+ int err;
+ struct kvm_one_reg reg;
+
+ reg.id = KVM_REG_ARM_TIMER_CNT;
+ reg.addr = (uintptr_t) tick_at_pause;
+
+ err = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, ®);
+ return err;
+}
+
+static int set_vcpu_timer_tick(CPUState *cs, uint64_t tick_at_pause)
+{
+ int err;
+ struct kvm_one_reg reg;
+
+ reg.id = KVM_REG_ARM_TIMER_CNT;
+ reg.addr = (uintptr_t) &tick_at_pause;
+
+ err = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
+ return err;
+}
+
+static void arch_timer_change_state_handler(void *opaque, int running,
+ RunState state)
+{
+ static uint64_t hw_ticks_at_paused;
+ static RunState pre_state = RUN_STATE__MAX;
+ int err;
+ CPUState *cs = (CPUState *)opaque;
+
+ switch (state) {
+ case RUN_STATE_PAUSED:
+ err = get_vcpu_timer_tick(cs, &hw_ticks_at_paused);
+ if (err) {
+ error_report("Get vcpu timer tick failed: %d", err);
+ }
+ break;
+ case RUN_STATE_RUNNING:
+ if (pre_state == RUN_STATE_PAUSED) {
+ err = set_vcpu_timer_tick(cs, hw_ticks_at_paused);
+ if (err) {
+ error_report("Resume vcpu timer tick failed: %d", err);
+ }
+ }
+ break;
+ default:
+ break;
+ }
+
+ pre_state = state;
+}
+
int kvm_arm_vcpu_init(CPUState *cs)
{
ARMCPU *cpu = ARM_CPU(cs);
struct kvm_vcpu_init init;
+ /*
+ * Only add change state handler for arch timer once, for KVM will help to
+ * synchronize virtual timer of all VCPUs.
+ */
+ static bool arch_timer_change_state_handler_added;
+
+
+ if (!arch_timer_change_state_handler_added) {
+ qemu_add_vm_change_state_handler(arch_timer_change_state_handler, cs);
+ arch_timer_change_state_handler_added = true;
+ }
+
init.target = cpu->kvm_target;
memcpy(init.features, cpu->kvm_init_features, sizeof(init.features));
--
1.8.3.1
