When kvm-adjvtime is enabled the guest's cntvct[_el0] won't count
the time when the VM is stopped. That time is skipped by updating
cntvoff[_el2] on each transition to vm_running using the current
QEMU_CLOCK_VIRTUAL time. QEMU_CLOCK_VIRTUAL only ticks when the VM
is running.
This patch only provides the implementation. A subsequent patch
will provide the CPU property allowing the feature to be enabled.
Reported-by: Bijan Mottahedeh <bijan.mottahe...@oracle.com>
Suggested-by: Bijan Mottahedeh <bijan.mottahe...@oracle.com>
Signed-off-by: Andrew Jones <drjo...@redhat.com>
---
target/arm/cpu.h | 3 +++
target/arm/kvm.c | 20 ++++++++++++++++++++
target/arm/kvm32.c | 15 +++++++++++++++
target/arm/kvm64.c | 15 +++++++++++++++
target/arm/kvm_arm.h | 12 ++++++++++++
5 files changed, 65 insertions(+)
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 5b9c3e4cd73d..923bd5e6384d 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -821,6 +821,9 @@ struct ARMCPU {
/* KVM init features for this CPU */
uint32_t kvm_init_features[7];
+ /* KVM CPU features */
+ bool kvm_adjvtime;
+
/* Uniprocessor system with MP extensions */
bool mp_is_up;
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 7a540d9591f9..f79b9b8ef57a 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -571,6 +571,26 @@ int kvm_arm_sync_mpstate_to_qemu(ARMCPU *cpu)
return 0;
}
+void kvm_arm_set_virtual_time(CPUState *cs)
+{
+ uint64_t cnt;
+ struct kvm_one_reg reg = {
+ .id = KVM_REG_ARM_TIMER_CNT,
+ .addr = (uintptr_t)&cnt,
+ };
+ int ret;
+
+ cnt = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
+ cpu_get_host_tick_frequency(),
+ NANOSECONDS_PER_SECOND);
+
+ ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
+ if (ret) {
+ error_report("Failed to set KVM_REG_ARM_TIMER_CNT");
+ abort();
+ }
+}
+
int kvm_put_vcpu_events(ARMCPU *cpu)
{
CPUARMState *env = &cpu->env;
diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
index 32bf8d6757c4..79c6013066a9 100644
--- a/target/arm/kvm32.c
+++ b/target/arm/kvm32.c
@@ -16,6 +16,7 @@
#include "qemu-common.h"
#include "cpu.h"
#include "qemu/timer.h"
+#include "sysemu/runstate.h"
#include "sysemu/kvm.h"
#include "kvm_arm.h"
#include "internals.h"
@@ -183,6 +184,18 @@ int kvm_arm_cpreg_level(uint64_t regidx)
return KVM_PUT_RUNTIME_STATE;
}
+static void kvm_arm_vm_state_change(void *opaque, int running, RunState state)
+{
+ CPUState *cs = opaque;
+ ARMCPU *cpu = ARM_CPU(cs);
+
+ if (running) {
+ if (cpu->kvm_adjvtime) {
+ kvm_arm_set_virtual_time(cs);
+ }
+ }
+}
+
#define ARM_CPU_ID_MPIDR 0, 0, 0, 5
int kvm_arch_init_vcpu(CPUState *cs)
@@ -198,6 +211,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
return -EINVAL;
}
+ qemu_add_vm_change_state_handler(kvm_arm_vm_state_change, cs);
+
/* Determine init features for this CPU */
memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
if (cpu->start_powered_off) {
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 5cafcb7d36dd..494cf7f8a5cd 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -23,6 +23,7 @@
#include "qemu/host-utils.h"
#include "qemu/main-loop.h"
#include "exec/gdbstub.h"
+#include "sysemu/runstate.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_int.h"
#include "kvm_arm.h"
@@ -720,6 +721,18 @@ static int kvm_arm_sve_set_vls(CPUState *cs)
return kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
}
+static void kvm_arm_vm_state_change(void *opaque, int running, RunState state)
+{
+ CPUState *cs = opaque;
+ ARMCPU *cpu = ARM_CPU(cs);
+
+ if (running) {
+ if (cpu->kvm_adjvtime) {
+ kvm_arm_set_virtual_time(cs);
+ }
+ }
+}
+
#define ARM_CPU_ID_MPIDR 3, 0, 0, 0, 5
int kvm_arch_init_vcpu(CPUState *cs)
@@ -735,6 +748,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
return -EINVAL;
}
+ qemu_add_vm_change_state_handler(kvm_arm_vm_state_change, cs);
+
/* Determine init features for this CPU */
memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
if (cpu->start_powered_off) {
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index a1cc6513f72b..d506c4e84be6 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -232,6 +232,16 @@ void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map);
*/
void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
+/**
+ * void kvm_arm_set_virtual_time:
+ * @cs: CPUState
+ *
+ * Sets the guest's virtual counter offset to the difference of the host's
+ * current time and QEMU's QEMU_CLOCK_VIRTUAL time. This allows the
+ * guest's virtual counter to only reflect VM running time.
+ */
+void kvm_arm_set_virtual_time(CPUState *cs);
+
/**
* kvm_arm_aarch32_supported:
* @cs: CPUState
@@ -323,6 +333,8 @@ static inline int kvm_arm_vgic_probe(void)
return 0;
}
+static inline void kvm_arm_set_virtual_time(CPUState *cs) {}
+
static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq) {}
static inline void kvm_arm_pmu_init(CPUState *cs) {}
--
2.20.1
