From: Radim Krčmář <rkrcmar@redhat.com>
Date: Wed, 15 Feb 2017 19:27:20 +0000 (+0100)
Subject: ptp_kvm: try to detect hypercall availability
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4306f200c71b959c44c32c8a0048fd5857a357c5;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

ptp_kvm: try to detect hypercall availability

No point in registering the device if it cannot work.
The hypercall does not advertise itself, so we have to call it.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/drivers/ptp/ptp_kvm.c b/drivers/ptp/ptp_kvm.c
index 0a54e8326a90..09b4df74291e 100644
--- a/drivers/ptp/ptp_kvm.c
+++ b/drivers/ptp/ptp_kvm.c
@@ -176,12 +176,19 @@ static void __exit ptp_kvm_exit(void)
 
 static int __init ptp_kvm_init(void)
 {
+	long ret;
+
 	clock_pair_gpa = slow_virt_to_phys(&clock_pair);
 	hv_clock = pvclock_pvti_cpu0_va();
 
 	if (!hv_clock)
 		return -ENODEV;
 
+	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
+			KVM_CLOCK_PAIRING_WALLCLOCK);
+	if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP)
+		return -ENODEV;
+
 	kvm_ptp_clock.caps = ptp_kvm_caps;
 
 	kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);