ptp: fix error print of ptp_kvm on X86_64 platform

Commit a86ed2cfa13c5 ("ptp: Don't print an error if ptp_kvm is not supported")
fixes the error message print on ARM platform by only concerning about
the case that the error returned from kvm_arch_ptp_init() is not -EOPNOTSUPP.
Although the ARM platform returns -EOPNOTSUPP if ptp_kvm is not supported
while X86_64 platform returns -KVM_EOPNOTSUPP, both error codes share the
same value 95.

Actually kvm_arch_ptp_init() on X86_64 platform can return three kinds of
errors (-KVM_ENOSYS, -KVM_EOPNOTSUPP and -KVM_EFAULT). The problem is that
-KVM_EOPNOTSUPP is masked out and -KVM_EFAULT is ignored among them.
This patch fixes this by returning them to ptp_kvm_init() respectively.

Signed-off-by: Kele Huang <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/ptp/ptp_kvm_x86.c

···
 
 	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
 			     KVM_CLOCK_PAIRING_WALLCLOCK);
-	if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP)
+	if (ret == -KVM_ENOSYS)
 		return -ENODEV;
 
-	return 0;
+	return ret;
 }
 
 int kvm_arch_ptp_get_clock(struct timespec64 *ts)