[PATCH 06/11] KVM: nVMX: Force MSR bitmap refresh if runtime eVMCS controls are modified

[Paolo Bonzini]

From: Sean Christopherson <seanjc@xxxxxxxxxx>

Force a refresh of the vmcs02 MSR bitmap during nested VM-Enter if the
runtime eVMCS controls (pin, primary, secondary, etc.) are being updated.
If L1 isn't intercepting TPR writes, runs L2 with TPR virtualization, and
then runs the same L2 with TPR virtualization disabled, KVM will fail to
refresh msr_bitmap02 and leave TPR in passthrough mode even though TPR
virtualization is disabled.  I.e. failure to refresh the bitmap lets L2 (or
L1 by proxy) read and write L0's TPR.

Fixes: 502d2bf5f2fd ("KVM: nVMX: Implement Enlightened MSR Bitmap feature")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 40c1a5f6fa8a..b25216862740 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1754,6 +1754,9 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
 static void copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx, u32 hv_clean_fields)
 {
 #ifdef CONFIG_KVM_HYPERV
+	const u64 runtime_controls = HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_GRP1 |
+				     HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_GRP2 |
+				     HV_VMX_ENLIGHTENED_CLEAN_FIELD_CONTROL_PROC;
 	struct vmcs12 *vmcs12 = vmx->nested.cached_vmcs12;
 	struct hv_enlightened_vmcs *evmcs = nested_vmx_evmcs(vmx);
 	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(&vmx->vcpu);
@@ -1762,6 +1765,9 @@ static void copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx, u32 hv_clean_fields
 	vmcs12->tpr_threshold = evmcs->tpr_threshold;
 	vmcs12->guest_rip = evmcs->guest_rip;
 
+	if ((hv_clean_fields & runtime_controls) != runtime_controls)
+		vmx->nested.force_msr_bitmap_recalc = true;
+
 	if (unlikely(!(hv_clean_fields &
 		       HV_VMX_ENLIGHTENED_CLEAN_FIELD_ENLIGHTENMENTSCONTROL))) {
 		hv_vcpu->nested.pa_page_gpa = evmcs->partition_assist_page;
-- 
2.52.0