4 files changed, 29 insertions, 4 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b31a3417a405..6ab4241c27cb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -630,6 +630,7 @@ struct kvm_x86_ops {
         void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
         u64 (*compute_tsc_offset)(struct kvm_vcpu *vcpu, u64 target_tsc);
+        u64 (*read_l1_tsc)(struct kvm_vcpu *vcpu);
 
         void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f043168a5ab1..590d1d2d620b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2910,6 +2910,13 @@ static int cr8_write_interception(struct vcpu_svm *svm)
         return 0;
 }
 
+u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu)
+{
+        struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu));
+        return vmcb->control.tsc_offset +
+                svm_scale_tsc(vcpu, native_read_tsc());
+}
+
 static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
@@ -4201,6 +4208,7 @@ static struct kvm_x86_ops svm_x86_ops = {
         .write_tsc_offset = svm_write_tsc_offset,
         .adjust_tsc_offset = svm_adjust_tsc_offset,
         .compute_tsc_offset = svm_compute_tsc_offset,
+        .read_l1_tsc = svm_read_l1_tsc,
 
         .set_tdp_cr3 = set_tdp_cr3,
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 03df703c8f20..97b64543d4ed 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1748,6 +1748,21 @@ static u64 guest_read_tsc(void)
 }
 
 /*
+ * Like guest_read_tsc, but always returns L1's notion of the timestamp
+ * counter, even if a nested guest (L2) is currently running.
+ */
+u64 vmx_read_l1_tsc(struct kvm_vcpu *vcpu)
+{
+        u64 host_tsc, tsc_offset;
+
+        rdtscll(host_tsc);
+        tsc_offset = is_guest_mode(vcpu) ?
+                to_vmx(vcpu)->nested.vmcs01_tsc_offset :
+                vmcs_read64(TSC_OFFSET);
+        return host_tsc + tsc_offset;
+}
+
+/*
  * Empty call-back. Needs to be implemented when VMX enables the SET_TSC_KHZ
  * ioctl. In this case the call-back should update internal vmx state to make
  * the changes effective.
@@ -7010,6 +7025,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
         .write_tsc_offset = vmx_write_tsc_offset,
         .adjust_tsc_offset = vmx_adjust_tsc_offset,
         .compute_tsc_offset = vmx_compute_tsc_offset,
+        .read_l1_tsc = vmx_read_l1_tsc,
 
         .set_tdp_cr3 = vmx_set_cr3,
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ea8f9f03e923..6b37f18a1663 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1098,7 +1098,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 
         /* Keep irq disabled to prevent changes to the clock */
         local_irq_save(flags);
-        kvm_get_msr(v, MSR_IA32_TSC, &tsc_timestamp);
+        tsc_timestamp = kvm_x86_ops->read_l1_tsc(v);
         kernel_ns = get_kernel_ns();
         this_tsc_khz = vcpu_tsc_khz(v);
         if (unlikely(this_tsc_khz == 0)) {
@@ -2218,7 +2218,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
                 s64 tsc_delta;
                 u64 tsc;
 
-                kvm_get_msr(vcpu, MSR_IA32_TSC, &tsc);
+                tsc = kvm_x86_ops->read_l1_tsc(vcpu);
                 tsc_delta = !vcpu->arch.last_guest_tsc ? 0 :
                              tsc - vcpu->arch.last_guest_tsc;
 
@@ -2242,7 +2242,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
         kvm_x86_ops->vcpu_put(vcpu);
         kvm_put_guest_fpu(vcpu);
-        kvm_get_msr(vcpu, MSR_IA32_TSC, &vcpu->arch.last_guest_tsc);
+        vcpu->arch.last_guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu);
 }
 
 static int is_efer_nx(void)
@@ -5729,7 +5729,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
         if (hw_breakpoint_active())
                 hw_breakpoint_restore();
 
-        kvm_get_msr(vcpu, MSR_IA32_TSC, &vcpu->arch.last_guest_tsc);
+        vcpu->arch.last_guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu);
 
         vcpu->mode = OUTSIDE_GUEST_MODE;
         smp_wmb();