On 5/18/20 1:15 PM, Makarand Sonare wrote:
From: Peter Shier <pshier@xxxxxxxxxx>
Add new field to hold preemption timer expiration deadline
appended to struct kvm_vmx_nested_state_data. 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>
Change-Id: I6446aba5a547afa667f0ef4620b1b76115bf3753
---
Documentation/virt/kvm/api.rst | 4 ++
arch/x86/include/uapi/asm/kvm.h | 2 +
arch/x86/kvm/vmx/nested.c | 61 ++++++++++++++++++++++++---
arch/x86/kvm/vmx/vmx.h | 1 +
arch/x86/kvm/x86.c | 3 +-
include/uapi/linux/kvm.h | 1 +
tools/arch/x86/include/uapi/asm/kvm.h | 2 +
7 files changed, 67 insertions(+), 7 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index d871dacb984e9..b410815772970 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4326,6 +4326,9 @@ Errors:
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
#define KVM_STATE_NESTED_EVMCS 0x00000004
+ /* Available with KVM_CAP_NESTED_STATE_PREEMPTION_TIMER */
+ #define KVM_STATE_NESTED_PREEMPTION_TIMER 0x00000010
+
#define KVM_STATE_NESTED_FORMAT_VMX 0
#define KVM_STATE_NESTED_FORMAT_SVM 1
@@ -4346,6 +4349,7 @@ Errors:
struct kvm_vmx_nested_state_data {
__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
__u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+ __u64 preemption_timer_deadline;
};
This ioctl copies the vcpu's nested virtualization state from the kernel to
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 3f3f780c8c650..20d5832bab215 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -391,6 +391,7 @@ struct kvm_sync_regs {
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
#define KVM_STATE_NESTED_EVMCS 0x00000004
#define KVM_STATE_NESTED_MTF_PENDING 0x00000008
+#define KVM_STATE_NESTED_PREEMPTION_TIMER 0x00000010
#define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_SMM_VMXON 0x00000002
@@ -400,6 +401,7 @@ struct kvm_sync_regs {
struct kvm_vmx_nested_state_data {
__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
__u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+ __u64 preemption_timer_deadline;
};
struct kvm_vmx_nested_state_hdr {
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 51ebb60e1533a..badb82a39ac04 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2092,9 +2092,9 @@ 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 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 +3353,24 @@ 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;
+ u64 l1_tsc_value = kvm_read_l1_tsc(vcpu, rdtsc());
+
+ if (from_vmentry) {
+ timer_value = vmcs12->vmx_preemption_timer_value;
+ vmx->nested.preemption_timer_deadline = timer_value +
+ (l1_tsc_value >> VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE);
+ } else {
+ if ((l1_tsc_value >> VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE) >
+ vmx->nested.preemption_timer_deadline)
+ timer_value = 0;
+ else
+ timer_value = vmx->nested.preemption_timer_deadline -
+ (l1_tsc_value >> VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE);
A couple of code optimizations can be done here:
1. The inside if-else can be simplified by initializing 'timer_value' at
the place where you have defined it:
} else {
+ if (!((l1_tsc_value >>
VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE) >
+ vmx->nested.preemption_timer_deadline))
+ timer_value = vmx->nested.preemption_timer_deadline -
+ (l1_tsc_value >>
VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE);
+ }
2. You can apply the right-shift operation on 'l1_tsc_value' right where
you have defined it:
u64 l1_tsc_value = kvm_read_l1_tsc(vcpu, rdtsc()) >>
VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE
+ }
+ vmx_start_preemption_timer(vcpu, timer_value);
+ }
/*
* Note no nested_vmx_succeed or nested_vmx_fail here. At this point
@@ -3962,9 +3978,11 @@ 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)
+ !vmx->nested.nested_run_pending) {
+ if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
vmcs12->vmx_preemption_timer_value =
vmx_get_preemption_timer_value(vcpu);
+ }
/*
* In some cases (usually, nested EPT), L2 is allowed to change its
@@ -5939,6 +5957,13 @@ 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)) {
+ kvm_state.flags |=
+ KVM_STATE_NESTED_PREEMPTION_TIMER;
+ kvm_state.size = offsetof(struct kvm_nested_state, data.vmx) +
'size' is reset here instead of accumulating all previous sizes. Is that
what is intended ?
+ offsetofend(struct kvm_vmx_nested_state_data, preemption_timer_deadline);
+ }
}
}
@@ -5970,6 +5995,9 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
BUILD_BUG_ON(sizeof(user_vmx_nested_state->vmcs12) < VMCS12_SIZE);
BUILD_BUG_ON(sizeof(user_vmx_nested_state->shadow_vmcs12) < VMCS12_SIZE);
+ BUILD_BUG_ON(sizeof(user_vmx_nested_state->preemption_timer_deadline)
+ != sizeof(vmx->nested.preemption_timer_deadline));
+
/*
* Copy over the full allocated size of vmcs12 rather than just the size
@@ -5985,6 +6013,12 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
return -EFAULT;
}
+ if (kvm_state.flags & KVM_STATE_NESTED_PREEMPTION_TIMER) {
+ if (put_user(vmx->nested.preemption_timer_deadline,
+ &user_vmx_nested_state->preemption_timer_deadline))
+ return -EFAULT;
+ }
+
out:
return kvm_state.size;
}
@@ -6056,7 +6090,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
*/
if (is_smm(vcpu) ?
(kvm_state->flags &
- (KVM_STATE_NESTED_GUEST_MODE | KVM_STATE_NESTED_RUN_PENDING))
+ (KVM_STATE_NESTED_GUEST_MODE | KVM_STATE_NESTED_RUN_PENDING |
+ KVM_STATE_NESTED_PREEMPTION_TIMER))
: kvm_state->hdr.vmx.smm.flags)
return -EINVAL;
@@ -6146,6 +6181,20 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
goto error_guest_mode;
}
+ if (kvm_state->flags & KVM_STATE_NESTED_PREEMPTION_TIMER) {
+
+ if (kvm_state->size <
+ offsetof(struct kvm_nested_state, data.vmx) +
+ offsetofend(struct kvm_vmx_nested_state_data, preemption_timer_deadline))
+ goto error_guest_mode;
+
+ if (get_user(vmx->nested.preemption_timer_deadline,
+ &user_vmx_nested_state->preemption_timer_deadline)) {
+ ret = -EFAULT;
+ goto error_guest_mode;
+ }
+ }
+
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..db697400755fb 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -169,6 +169,7 @@ struct nested_vmx {
u16 posted_intr_nv;
struct hrtimer preemption_timer;
+ u64 preemption_timer_deadline;
bool preemption_timer_expired;
/* to migrate it to L2 if VM_ENTRY_LOAD_DEBUG_CONTROLS is off */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 471fccf7f8501..ba9e62ffbb4cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3418,6 +3418,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_MSR_PLATFORM_INFO:
case KVM_CAP_EXCEPTION_PAYLOAD:
case KVM_CAP_SET_GUEST_DEBUG:
+ case KVM_CAP_NESTED_STATE_PREEMPTION_TIMER:
r = 1;
break;
case KVM_CAP_SYNC_REGS:
@@ -4626,7 +4627,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
if (kvm_state.flags &
~(KVM_STATE_NESTED_RUN_PENDING | KVM_STATE_NESTED_GUEST_MODE
- | KVM_STATE_NESTED_EVMCS))
+ | KVM_STATE_NESTED_EVMCS | KVM_STATE_NESTED_PREEMPTION_TIMER))
break;
/* nested_run_pending implies guest_mode. */
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index ac9eba0289d1b..0868dce12a715 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1018,6 +1018,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_S390_PROTECTED 180
#define KVM_CAP_PPC_SECURE_GUEST 181
#define KVM_CAP_HALT_POLL 182
+#define KVM_CAP_NESTED_STATE_PREEMPTION_TIMER 183
#ifdef KVM_CAP_IRQ_ROUTING
diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 3f3f780c8c650..60701178b9cc1 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -391,6 +391,8 @@ struct kvm_sync_regs {
#define KVM_STATE_NESTED_RUN_PENDING 0x00000002
#define KVM_STATE_NESTED_EVMCS 0x00000004
#define KVM_STATE_NESTED_MTF_PENDING 0x00000008
+/* Available with KVM_CAP_NESTED_STATE_PREEMPTION_TIMER */
+#define KVM_STATE_NESTED_PREEMPTION_TIMER 0x00000010
#define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001
#define KVM_STATE_NESTED_SMM_VMXON 0x00000002
