From: Ilias Stamatis <ilstam@xxxxxxxxxx>
Calculating the current TSC offset is done differently when nested TSC
scaling is used.
Signed-off-by: Ilias Stamatis <ilstam@xxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 49241423b854..df7dc0e4c903 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1797,10 +1797,16 @@ static void setup_msrs(struct vcpu_vmx *vmx)
vmx_update_msr_bitmap(&vmx->vcpu);
}
-static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
+/*
+ * This function receives the requested offset for L1 as an argument but it
+ * actually writes the "current" tsc offset to the VMCS and returns it. The
+ * current offset might be different in case an L2 guest is currently running
+ * and its VMCS02 is loaded.
+ */
+static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 l1_offset)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
- u64 g_tsc_offset = 0;
+ u64 cur_offset = l1_offset;
/*
* We're here if L1 chose not to trap WRMSR to TSC. According
@@ -1809,11 +1815,19 @@ static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
* to the newly set TSC to get L2's TSC.
*/
if (is_guest_mode(vcpu) &&
- (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING))
- g_tsc_offset = vmcs12->tsc_offset;
+ (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)) {
+ if (vmcs12->secondary_vm_exec_control & SECONDARY_EXEC_TSC_SCALING) {
+ cur_offset = kvm_compute_02_tsc_offset(
+ l1_offset,
+ vmcs12->tsc_multiplier,
+ vmcs12->tsc_offset);
+ } else {
+ cur_offset = l1_offset + vmcs12->tsc_offset;
+ }
+ }
- vmcs_write64(TSC_OFFSET, offset + g_tsc_offset);
- return offset + g_tsc_offset;
+ vmcs_write64(TSC_OFFSET, cur_offset);
+ return cur_offset;
}
/*
--
2.17.1
