KVM: nVMX: Use vmx_segment_cache_clear() instead of open coded equivalent

In prepare_vmcs02_rare(), call vmx_segment_cache_clear() instead of
setting segment_cache.bitmask directly.  Using the helper minimizes the
chances of prepare_vmcs02_rare() doing the wrong thing in the future, e.g.
if KVM ends up doing more than just zero the bitmask when purging the
cache.

No functional change intended.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20240725175232.337266-2-mlevitsk@redhat.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/vmx/nested.c

@@ -2470,6 +2470,7 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 
 	if (!hv_evmcs || !(hv_evmcs->hv_clean_fields &
 			   HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2)) {
+
 		vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector);
 		vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector);
 		vmcs_write16(GUEST_SS_SELECTOR, vmcs12->guest_ss_selector);
@@ -2507,7 +2508,7 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 		vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base);
 		vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base);
 
-		vmx->segment_cache.bitmask = 0;
+		vmx_segment_cache_clear(vmx);
 	}
 
 	if (!hv_evmcs || !(hv_evmcs->hv_clean_fields &

arch/x86/kvm/vmx/vmx.c

@@ -525,10 +525,6 @@ static const struct kvm_vmx_segment_field {
 	VMX_SEGMENT_FIELD(LDTR),
 };
 
-static inline void vmx_segment_cache_clear(struct vcpu_vmx *vmx)
-{
-	vmx->segment_cache.bitmask = 0;
-}
 
 static unsigned long host_idt_base;
 

arch/x86/kvm/vmx/vmx.h

@@ -756,4 +756,9 @@ static inline bool vmx_can_use_ipiv(struct kvm_vcpu *vcpu)
 	return  lapic_in_kernel(vcpu) && enable_ipiv;
 }
 
+static inline void vmx_segment_cache_clear(struct vcpu_vmx *vmx)
+{
+	vmx->segment_cache.bitmask = 0;
+}
+
 #endif /* __KVM_X86_VMX_H */