KVM: x86: Use ERR_PTR_USR() to return -EFAULT as a __user pointer

Use ERR_PTR_USR() when returning -EFAULT from kvm_get_attr_addr(), sparse
complains about implicitly casting the kernel pointer from ERR_PTR() into
a __user pointer.

>> arch/x86/kvm/x86.c:4342:31: sparse: sparse: incorrect type in return expression
   (different address spaces) @@     expected void [noderef] __user * @@     got void * @@
   arch/x86/kvm/x86.c:4342:31: sparse:     expected void [noderef] __user *
   arch/x86/kvm/x86.c:4342:31: sparse:     got void *
>> arch/x86/kvm/x86.c:4342:31: sparse: sparse: incorrect type in return expression
   (different address spaces) @@     expected void [noderef] __user * @@     got void * @@
   arch/x86/kvm/x86.c:4342:31: sparse:     expected void [noderef] __user *
   arch/x86/kvm/x86.c:4342:31: sparse:     got void *

No functional change intended.

Fixes: 56f289a8 ("KVM: x86: Add a helper to retrieve userspace address from kvm_device_attr")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220202005157.2545816-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -90,6 +90,8 @@
 u64 __read_mostly kvm_mce_cap_supported = MCG_CTL_P | MCG_SER_P;
 EXPORT_SYMBOL_GPL(kvm_mce_cap_supported);
 
+#define  ERR_PTR_USR(e)  ((void __user *)ERR_PTR(e))
+
 #define emul_to_vcpu(ctxt) \
 	((struct kvm_vcpu *)(ctxt)->vcpu)
 
@@ -4340,7 +4342,7 @@ static inline void __user *kvm_get_attr_addr(struct kvm_device_attr *attr)
 	void __user *uaddr = (void __user*)(unsigned long)attr->addr;
 
 	if ((u64)(unsigned long)uaddr != attr->addr)
-		return ERR_PTR(-EFAULT);
+		return ERR_PTR_USR(-EFAULT);
 	return uaddr;
 }
 
@@ -11684,8 +11686,6 @@ void kvm_arch_sync_events(struct kvm *kvm)
 	kvm_free_pit(kvm);
 }
 
-#define  ERR_PTR_USR(e)  ((void __user *)ERR_PTR(e))
-
 /**
  * __x86_set_memory_region: Setup KVM internal memory slot
  *