xen/x86: allow disabling the emulated RTC

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
Changes since v6:
 - Return ENODEV in rtc_load if rtc is disabled.
 - Add checks to rtc_reset and rtc_update_clock to prevent calling them if
   rtc is disabled.

Changes since v4:
 - Add Andrew Cooper Acked-by.

diff --git a/xen/arch/x86/hvm/rtc.c b/xen/arch/x86/hvm/rtc.c
index a9efeaf50a025ecb5b4e9a4592f62caf3d072378..d391e38ae59b188a9dce240e4828b87266e7d8d7 100644 (file)
--- a/xen/arch/x86/hvm/rtc.c
+++ b/xen/arch/x86/hvm/rtc.c
@@ -726,6 +726,9 @@ void rtc_migrate_timers(struct vcpu *v)
 {
     RTCState *s = vcpu_vrtc(v);
 
+    if ( !has_vrtc(v->domain) )
+        return;
+
     if ( v->vcpu_id == 0 )
     {
         migrate_timer(&s->update_timer, v->processor);;
@@ -739,6 +742,10 @@ static int rtc_save(struct domain *d, hvm_domain_context_t *h)
 {
     RTCState *s = domain_vrtc(d);
     int rc;
+
+    if ( !has_vrtc(d) )
+        return 0;
+
     spin_lock(&s->lock);
     rc = hvm_save_entry(RTC, 0, h, &s->hw);
     spin_unlock(&s->lock);
@@ -750,6 +757,9 @@ static int rtc_load(struct domain *d, hvm_domain_context_t *h)
 {
     RTCState *s = domain_vrtc(d);
 
+    if ( !has_vrtc(d) )
+        return -ENODEV;
+
     spin_lock(&s->lock);
 
     /* Restore the registers */
@@ -780,6 +790,9 @@ void rtc_reset(struct domain *d)
 {
     RTCState *s = domain_vrtc(d);
 
+    if ( !has_vrtc(d) )
+        return;
+
     TRACE_0D(TRC_HVM_EMUL_RTC_STOP_TIMER);
     destroy_periodic_time(&s->pt);
     s->period = 0;
@@ -790,6 +803,9 @@ void rtc_init(struct domain *d)
 {
     RTCState *s = domain_vrtc(d);
 
+    if ( !has_vrtc(d) )
+        return;
+
     spin_lock_init(&s->lock);
 
     init_timer(&s->update_timer, rtc_update_timer, s, smp_processor_id());
@@ -820,6 +836,9 @@ void rtc_deinit(struct domain *d)
 {
     RTCState *s = domain_vrtc(d);
 
+    if ( !has_vrtc(d) )
+        return;
+
     spin_barrier(&s->lock);
 
     TRACE_0D(TRC_HVM_EMUL_RTC_STOP_TIMER);
@@ -833,6 +852,9 @@ void rtc_update_clock(struct domain *d)
 {
     RTCState *s = domain_vrtc(d);
 
+    if ( !has_vrtc(d) )
+        return;
+
     spin_lock(&s->lock);
     s->current_tm = gmtime(get_localtime(d));
     spin_unlock(&s->lock);