KVM: x86: make Hyper-V PV TLB flush use tlb_flush_guest()

Hyper-V PV TLB flush mechanism does TLB flush on behalf of the guest
so doing tlb_flush_all() is an overkill, switch to using tlb_flush_guest()
(just like KVM PV TLB flush mechanism) instead. Introduce
KVM_REQ_HV_TLB_FLUSH to support the change.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -83,6 +83,8 @@
 #define KVM_REQ_GET_VMCS12_PAGES	KVM_ARCH_REQ(24)
 #define KVM_REQ_APICV_UPDATE \
 	KVM_ARCH_REQ_FLAGS(25, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_HV_TLB_FLUSH \
+	KVM_ARCH_REQ_FLAGS(26, KVM_REQUEST_NO_WAKEUP)
 
 #define CR0_RESERVED_BITS                                               \
 	(~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \

arch/x86/kvm/hyperv.c

@@ -1425,8 +1425,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 	 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't
 	 * analyze it here, flush TLB regardless of the specified address space.
 	 */
-	kvm_make_vcpus_request_mask(kvm,
-				    KVM_REQ_TLB_FLUSH | KVM_REQUEST_NO_WAKEUP,
+	kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH,
 				    vcpu_mask, &hv_vcpu->tlb_flush);
 
 ret_success:

arch/x86/kvm/x86.c

@@ -2696,6 +2696,12 @@ static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa)
 	kvm_x86_ops.tlb_flush(vcpu, invalidate_gpa);
 }
 
+static void kvm_vcpu_flush_tlb_guest(struct kvm_vcpu *vcpu)
+{
+	++vcpu->stat.tlb_flush;
+	kvm_x86_ops.tlb_flush_guest(vcpu);
+}
+
 static void record_steal_time(struct kvm_vcpu *vcpu)
 {
 	struct kvm_host_map map;
@@ -2719,7 +2725,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
 	trace_kvm_pv_tlb_flush(vcpu->vcpu_id,
 		st->preempted & KVM_VCPU_FLUSH_TLB);
 	if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB)
-		kvm_x86_ops.tlb_flush_guest(vcpu);
+		kvm_vcpu_flush_tlb_guest(vcpu);
 
 	vcpu->arch.st.preempted = 0;
 
@@ -8218,6 +8224,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			kvm_mmu_load_pgd(vcpu);
 		if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu))
 			kvm_vcpu_flush_tlb(vcpu, true);
+		if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
+			kvm_vcpu_flush_tlb_guest(vcpu);
 		if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) {
 			vcpu->run->exit_reason = KVM_EXIT_TPR_ACCESS;
 			r = 0;