KVM: use __copy_to_user/__clear_user to write guest page

Simply use __copy_to_user/__clear_user to write guest page since we have
already verified the user address when the memslot is set
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/x86.c

@@ -1388,7 +1388,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 			return 1;
 		kvm_x86_ops->patch_hypercall(vcpu, instructions);
 		((unsigned char *)instructions)[3] = 0xc3; /* ret */
-		if (copy_to_user((void __user *)addr, instructions, 4))
+		if (__copy_to_user((void __user *)addr, instructions, 4))
 			return 1;
 		kvm->arch.hv_hypercall = data;
 		break;
@@ -1415,7 +1415,7 @@ static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 				  HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT);
 		if (kvm_is_error_hva(addr))
 			return 1;
-		if (clear_user((void __user *)addr, PAGE_SIZE))
+		if (__clear_user((void __user *)addr, PAGE_SIZE))
 			return 1;
 		vcpu->arch.hv_vapic = data;
 		break;

virt/kvm/kvm_main.c

@@ -1345,7 +1345,7 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
 	addr = gfn_to_hva(kvm, gfn);
 	if (kvm_is_error_hva(addr))
 		return -EFAULT;
-	r = copy_to_user((void __user *)addr + offset, data, len);
+	r = __copy_to_user((void __user *)addr + offset, data, len);
 	if (r)
 		return -EFAULT;
 	mark_page_dirty(kvm, gfn);
@@ -1405,7 +1405,7 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 	if (kvm_is_error_hva(ghc->hva))
 		return -EFAULT;
 
-	r = copy_to_user((void __user *)ghc->hva, data, len);
+	r = __copy_to_user((void __user *)ghc->hva, data, len);
 	if (r)
 		return -EFAULT;
 	mark_page_dirty_in_slot(kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT);