From: Peter Shier <pshier@xxxxxxxxxx>
Add new field to hold preemption timer expiration deadline
appended to struct kvm_vmx_nested_state_hdr. This is to prevent
the first VM-Enter after migration from incorrectly restarting the timer
with the full timer value instead of partially decayed timer value.
KVM_SET_NESTED_STATE restarts timer using migrated state regardless
of whether L1 sets VM_EXIT_SAVE_VMX_PREEMPTION_TIMER.
Fixes: cf8b84f48a593 ("kvm: nVMX: Prepare for checkpointing L2 state")
Signed-off-by: Peter Shier <pshier@xxxxxxxxxx>
Signed-off-by: Makarand Sonare <makarandsonare@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 4 +++
arch/x86/include/uapi/asm/kvm.h | 4 +++
arch/x86/kvm/vmx/nested.c | 55 ++++++++++++++++++++++++++++-----
arch/x86/kvm/vmx/vmx.h | 2 ++
4 files changed, 57 insertions(+), 8 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index d871dacb984e9..31d6402cb6532 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4334,9 +4334,13 @@ Errors:
#define KVM_STATE_NESTED_VMX_SMM_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_VMX_SMM_VMXON 0x00000002
+#define KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE 0x00000001
+
struct kvm_vmx_nested_state_hdr {
+ __u32 flags;
__u64 vmxon_pa;
__u64 vmcs12_pa;
+ __u64 preemption_timer_deadline;
struct {
__u16 flags;
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 3f3f780c8c650..acc26eb880eec 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -397,14 +397,18 @@ struct kvm_sync_regs {
#define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000
+#define KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE 0x00000001
+
struct kvm_vmx_nested_state_data {
__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
__u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
};
struct kvm_vmx_nested_state_hdr {
+ __u32 flags;
__u64 vmxon_pa;
__u64 vmcs12_pa;
+ __u64 preemption_timer_deadline;
struct {
__u16 flags;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 51ebb60e1533a..00db8a04d3c87 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2092,9 +2092,29 @@ static enum hrtimer_restart vmx_preemption_timer_fn(struct hrtimer *timer)
return HRTIMER_NORESTART;
}
-static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu)
+static u64 vmx_calc_preemption_timer_value(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+ u64 timer_value = 0;
+
+ u64 l1_scaled_tsc = kvm_read_l1_tsc(vcpu, rdtsc()) >>
+ VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE;
+
+ if (!vmx->nested.has_preemption_timer_deadline) {
+ timer_value = vmcs12->vmx_preemption_timer_value;
+ vmx->nested.preemption_timer_deadline = timer_value +
+ l1_scaled_tsc;
+ vmx->nested.has_preemption_timer_deadline = true;
+ } else if (l1_scaled_tsc < vmx->nested.preemption_timer_deadline)
+ timer_value = vmx->nested.preemption_timer_deadline -
+ l1_scaled_tsc;
+ return timer_value;
+}
+
+static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu,
+ u64 preemption_timeout)
{
- u64 preemption_timeout = get_vmcs12(vcpu)->vmx_preemption_timer_value;
struct vcpu_vmx *vmx = to_vmx(vcpu);
/*
@@ -3353,8 +3373,10 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
* the timer.
*/
vmx->nested.preemption_timer_expired = false;
- if (nested_cpu_has_preemption_timer(vmcs12))
- vmx_start_preemption_timer(vcpu);
+ if (nested_cpu_has_preemption_timer(vmcs12)) {
+ u64 timer_value = vmx_calc_preemption_timer_value(vcpu);
+ vmx_start_preemption_timer(vcpu, timer_value);
+ }
/*
* Note no nested_vmx_succeed or nested_vmx_fail here. At this point
@@ -3462,6 +3484,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
* the nested entry.
*/
vmx->nested.nested_run_pending = 1;
+ vmx->nested.has_preemption_timer_deadline = false;
status = nested_vmx_enter_non_root_mode(vcpu, true);
if (unlikely(status != NVMX_VMENTRY_SUCCESS))
goto vmentry_failed;
@@ -3962,9 +3985,10 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
vmcs12->guest_activity_state = GUEST_ACTIVITY_ACTIVE;
if (nested_cpu_has_preemption_timer(vmcs12) &&
- vmcs12->vm_exit_controls & VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
- vmcs12->vmx_preemption_timer_value =
- vmx_get_preemption_timer_value(vcpu);
+ vmcs12->vm_exit_controls & VM_EXIT_SAVE_VMX_PREEMPTION_TIMER &&
+ !vmx->nested.nested_run_pending)
+ vmcs12->vmx_preemption_timer_value =
+ vmx_get_preemption_timer_value(vcpu);
/*
* In some cases (usually, nested EPT), L2 is allowed to change its
@@ -5896,8 +5920,10 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
.flags = 0,
.format = KVM_STATE_NESTED_FORMAT_VMX,
.size = sizeof(kvm_state),
+ .hdr.vmx.flags = 0,
.hdr.vmx.vmxon_pa = -1ull,
.hdr.vmx.vmcs12_pa = -1ull,
+ .hdr.vmx.preemption_timer_deadline = 0,
};
struct kvm_vmx_nested_state_data __user *user_vmx_nested_state =
&user_kvm_nested_state->data.vmx[0];
@@ -5939,6 +5965,14 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
if (vmx->nested.mtf_pending)
kvm_state.flags |= KVM_STATE_NESTED_MTF_PENDING;
+
+ if (nested_cpu_has_preemption_timer(vmcs12) &&
+ vmx->nested.has_preemption_timer_deadline) {
+ kvm_state.hdr.vmx.flags |=
+ KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE;
+ kvm_state.hdr.vmx.preemption_timer_deadline =
+ vmx->nested.preemption_timer_deadline;
+ }
}
}
@@ -5984,7 +6018,6 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
get_shadow_vmcs12(vcpu), VMCS12_SIZE))
return -EFAULT;
}
-
out:
return kvm_state.size;
}
@@ -6146,6 +6179,12 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
goto error_guest_mode;
}
+ if (kvm_state->hdr.vmx.flags & KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE) {
+ vmx->nested.has_preemption_timer_deadline = true;
+ vmx->nested.preemption_timer_deadline =
+ kvm_state->hdr.vmx.preemption_timer_deadline;
+ }
+
if (nested_vmx_check_controls(vcpu, vmcs12) ||
nested_vmx_check_host_state(vcpu, vmcs12) ||
nested_vmx_check_guest_state(vcpu, vmcs12, &ignored))
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 298ddef79d009..672c28f17e497 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -169,6 +169,8 @@ struct nested_vmx {
u16 posted_intr_nv;
struct hrtimer preemption_timer;
+ u64 preemption_timer_deadline;
+ bool has_preemption_timer_deadline;
bool preemption_timer_expired;
/* to migrate it to L2 if VM_ENTRY_LOAD_DEBUG_CONTROLS is off */
--
2.27.0.rc0.183.gde8f92d652-goog
