KVM: nVMX: hyper-v: Cache VP assist page in 'struct kvm_vcpu_hv'

In preparation to enabling L2 TLB flush, cache VP assist page in
'struct kvm_vcpu_hv'. While on it, rename nested_enlightened_vmentry()
to nested_get_evmptr() and make it return eVMCS GPA directly.

No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-26-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -669,6 +669,8 @@ struct kvm_vcpu_hv {
 	/* Preallocated buffer for handling hypercalls passing sparse vCPU set */
 	u64 sparse_banks[HV_MAX_SPARSE_VCPU_BANKS];
 
+	struct hv_vp_assist_page vp_assist_page;
+
 	struct {
 		u64 pa_page_gpa;
 		u64 vm_id;

arch/x86/kvm/hyperv.c

@@ -900,13 +900,15 @@ bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_hv_assist_page_enabled);
 
-bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu,
-			    struct hv_vp_assist_page *assist_page)
+bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu)
 {
-	if (!kvm_hv_assist_page_enabled(vcpu))
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+
+	if (!hv_vcpu || !kvm_hv_assist_page_enabled(vcpu))
 		return false;
+
 	return !kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.pv_eoi.data,
-				      assist_page, sizeof(*assist_page));
+				      &hv_vcpu->vp_assist_page, sizeof(struct hv_vp_assist_page));
 }
 EXPORT_SYMBOL_GPL(kvm_hv_get_assist_page);
 

arch/x86/kvm/hyperv.h

@@ -108,8 +108,7 @@ int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages);
 void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu);
 
 bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu);
-bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu,
-			    struct hv_vp_assist_page *assist_page);
+bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu);
 
 static inline struct kvm_vcpu_hv_stimer *to_hv_stimer(struct kvm_vcpu *vcpu,
 						      int timer_index)

arch/x86/kvm/vmx/hyperv.c

@@ -321,24 +321,17 @@ const struct evmcs_field vmcs_field_to_evmcs_1[] = {
 };
 const unsigned int nr_evmcs_1_fields = ARRAY_SIZE(vmcs_field_to_evmcs_1);
 
-bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa)
+u64 nested_get_evmptr(struct kvm_vcpu *vcpu)
 {
-	struct hv_vp_assist_page assist_page;
-
-	*evmcs_gpa = -1ull;
-
-	if (unlikely(!kvm_hv_get_assist_page(vcpu, &assist_page)))
-		return false;
-
-	if (unlikely(!assist_page.enlighten_vmentry))
-		return false;
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
 
-	if (unlikely(!evmptr_is_valid(assist_page.current_nested_vmcs)))
-		return false;
+	if (unlikely(!kvm_hv_get_assist_page(vcpu)))
+		return EVMPTR_INVALID;
 
-	*evmcs_gpa = assist_page.current_nested_vmcs;
+	if (unlikely(!hv_vcpu->vp_assist_page.enlighten_vmentry))
+		return EVMPTR_INVALID;
 
-	return true;
+	return hv_vcpu->vp_assist_page.current_nested_vmcs;
 }
 
 uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu)

arch/x86/kvm/vmx/hyperv.h

@@ -237,7 +237,7 @@ enum nested_evmptrld_status {
 	EVMPTRLD_ERROR,
 };
 
-bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa);
+u64 nested_get_evmptr(struct kvm_vcpu *vcpu);
 uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu);
 int nested_enable_evmcs(struct kvm_vcpu *vcpu,
 			uint16_t *vmcs_version);

arch/x86/kvm/vmx/nested.c

@@ -1992,7 +1992,8 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld(
 	if (likely(!guest_cpuid_has_evmcs(vcpu)))
 		return EVMPTRLD_DISABLED;
 
-	if (!nested_enlightened_vmentry(vcpu, &evmcs_gpa)) {
+	evmcs_gpa = nested_get_evmptr(vcpu);
+	if (!evmptr_is_valid(evmcs_gpa)) {
 		nested_release_evmcs(vcpu);
 		return EVMPTRLD_DISABLED;
 	}
@@ -5221,7 +5222,6 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u32 zero = 0;
 	gpa_t vmptr;
-	u64 evmcs_gpa;
 	int r;
 
 	if (!nested_vmx_check_permission(vcpu))
@@ -5247,7 +5247,7 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
 	 * vmx->nested.hv_evmcs but this shouldn't be a problem.
 	 */
 	if (likely(!guest_cpuid_has_evmcs(vcpu) ||
-		   !nested_enlightened_vmentry(vcpu, &evmcs_gpa))) {
+		   !evmptr_is_valid(nested_get_evmptr(vcpu)))) {
 		if (vmptr == vmx->nested.current_vmptr)
 			nested_release_vmcs12(vcpu);