KVM: x86: hyper-v: Use guard() instead of mutex_lock() to simplify code

Use guard(mutex) instead of mutex_lock/mutex_unlock pair to simplify the
error handling when setting up the TSC page for a Hyper-V guest.

No functional change intended.

Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
Link: https://lore.kernel.org/r/20250901131604.646415-1-liaoyuanhong@vivo.com
[sean: tweak changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: LiaoYuanhong-vivo

arch/x86/kvm/hyperv.c

@@ -1168,15 +1168,15 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
 	BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
 	BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);
 
-	mutex_lock(&hv->hv_lock);
+	guard(mutex)(&hv->hv_lock);
 
 	if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
 	    hv->hv_tsc_page_status == HV_TSC_PAGE_SET ||
 	    hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET)
-		goto out_unlock;
+		return;
 
 	if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
-		goto out_unlock;
+		return;
 
 	gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
 	/*
@@ -1192,7 +1192,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
 			goto out_err;
 
 		hv->hv_tsc_page_status = HV_TSC_PAGE_SET;
-		goto out_unlock;
+		return;
 	}
 
 	/*
@@ -1228,12 +1228,10 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
 		goto out_err;
 
 	hv->hv_tsc_page_status = HV_TSC_PAGE_SET;
-	goto out_unlock;
+	return;
 
 out_err:
 	hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN;
-out_unlock:
-	mutex_unlock(&hv->hv_lock);
 }
 
 void kvm_hv_request_tsc_page_update(struct kvm *kvm)