[PATCH v2 16/20] KVM: x86/xen: Convert xen_get_guest_pvclock() to gpc's CLASS() APIs

[Sean Christopherson <seanjc@google.com>]

Convert the Xen pvclock reads to the "map local" CLASS() APIs, using a
read-only variants as KVM simply copying data from the pvclock.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/xen.c | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 47750316f132..89daad3fe712 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -153,21 +153,11 @@ static int xen_get_guest_pvclock(struct kvm_vcpu *vcpu,
 				 struct gfn_to_pfn_cache *gpc,
 				 unsigned int offset)
 {
-	int r;
+	CLASS(gpc_map_local_ro, pvclock_map)(gpc, offset + sizeof(*hv_clock));
+	if (IS_ERR(pvclock_map))
+		return PTR_ERR(pvclock_map);
 
-	read_lock(&gpc->lock);
-	while (!kvm_gpc_check(gpc, offset + sizeof(*hv_clock))) {
-		read_unlock(&gpc->lock);
-
-		r = kvm_gpc_refresh(gpc, offset + sizeof(*hv_clock));
-		if (r)
-			return r;
-
-		read_lock(&gpc->lock);
-	}
-
-	memcpy(hv_clock, gpc->khva + offset, sizeof(*hv_clock));
-	read_unlock(&gpc->lock);
+	memcpy(hv_clock, *pvclock_map + offset, sizeof(*hv_clock));
 
 	/*
 	 * Sanity check TSC shift+multiplier to verify the guest's view of time
-- 
2.54.0.823.g6e5bcc1fc9-goog