Implement Hyper-V L2 TLB flush for nSVM. The feature needs to be enabled
both in extended 'nested controls' in VMCB and partition assist page.
According to Hyper-V TLFS, synthetic vmexit to L1 is performed with
- HV_SVM_EXITCODE_ENL exit_code.
- HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH exit_info_1.
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/svm/hyperv.c | 7 +++++++
arch/x86/kvm/svm/hyperv.h | 19 +++++++++++++++++++
arch/x86/kvm/svm/nested.c | 27 +++++++++++++++++++++++++--
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/svm/hyperv.c b/arch/x86/kvm/svm/hyperv.c
index 911f51021af1..088f6429b24c 100644
--- a/arch/x86/kvm/svm/hyperv.c
+++ b/arch/x86/kvm/svm/hyperv.c
@@ -8,4 +8,11 @@
void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu)
{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ svm->vmcb->control.exit_code = HV_SVM_EXITCODE_ENL;
+ svm->vmcb->control.exit_code_hi = 0;
+ svm->vmcb->control.exit_info_1 = HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH;
+ svm->vmcb->control.exit_info_2 = 0;
+ nested_svm_vmexit(svm);
}
diff --git a/arch/x86/kvm/svm/hyperv.h b/arch/x86/kvm/svm/hyperv.h
index dd2e393f84a0..6ea78499e21b 100644
--- a/arch/x86/kvm/svm/hyperv.h
+++ b/arch/x86/kvm/svm/hyperv.h
@@ -33,6 +33,9 @@ struct hv_enlightenments {
*/
#define VMCB_HV_NESTED_ENLIGHTENMENTS VMCB_SW
+#define HV_SVM_EXITCODE_ENL 0xF0000000
+#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH (1)
+
static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -48,6 +51,22 @@ static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu)
hv_vcpu->nested.vp_id = hve->hv_vp_id;
}
+static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ struct hv_enlightenments *hve =
+ (struct hv_enlightenments *)svm->nested.ctl.reserved_sw;
+ struct hv_vp_assist_page assist_page;
+
+ if (unlikely(!kvm_hv_get_assist_page(vcpu, &assist_page)))
+ return false;
+
+ if (!hve->hv_enlightenments_control.nested_flush_hypercall)
+ return false;
+
+ return assist_page.nested_control.features.directhypercall;
+}
+
void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);
#endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b203e6cd75dc..083b95d85495 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -171,8 +171,12 @@ void recalc_intercepts(struct vcpu_svm *svm)
vmcb_clr_intercept(c, INTERCEPT_VINTR);
}
- /* We don't want to see VMMCALLs from a nested guest */
- vmcb_clr_intercept(c, INTERCEPT_VMMCALL);
+ /*
+ * We want to see VMMCALLs from a nested guest only when Hyper-V L2 TLB
+ * flush feature is enabled.
+ */
+ if (!nested_svm_l2_tlb_flush_enabled(&svm->vcpu))
+ vmcb_clr_intercept(c, INTERCEPT_VMMCALL);
for (i = 0; i < MAX_INTERCEPT; i++)
c->intercepts[i] |= g->intercepts[i];
@@ -489,6 +493,17 @@ static void nested_save_pending_event_to_vmcb12(struct vcpu_svm *svm,
static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
{
+ /*
+ * KVM_REQ_HV_TLB_FLUSH flushes entries from either L1's VP_ID or
+ * L2's VP_ID upon request from the guest. Make sure we check for
+ * pending entries for the case when the request got misplaced (e.g.
+ * a transition from L2->L1 happened while processing L2 TLB flush
+ * request or vice versa). kvm_hv_vcpu_flush_tlb() will not flush
+ * anything if there are no requests in the corresponding buffer.
+ */
+ if (to_hv_vcpu(vcpu))
+ kvm_make_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
+
/*
* TODO: optimize unconditional TLB flush/MMU sync. A partial list of
* things to fix before this can be conditional:
@@ -1409,6 +1424,7 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu)
int nested_svm_exit_special(struct vcpu_svm *svm)
{
u32 exit_code = svm->vmcb->control.exit_code;
+ struct kvm_vcpu *vcpu = &svm->vcpu;
switch (exit_code) {
case SVM_EXIT_INTR:
@@ -1427,6 +1443,13 @@ int nested_svm_exit_special(struct vcpu_svm *svm)
return NESTED_EXIT_HOST;
break;
}
+ case SVM_EXIT_VMMCALL:
+ /* Hyper-V L2 TLB flush hypercall is handled by L0 */
+ if (guest_hv_cpuid_has_l2_tlb_flush(vcpu) &&
+ nested_svm_l2_tlb_flush_enabled(vcpu) &&
+ kvm_hv_is_tlb_flush_hcall(vcpu))
+ return NESTED_EXIT_HOST;
+ break;
default:
break;
}
--
2.35.3
