[PATCH v2 05/12] x86/hvm: Remove duplicate calls caused by tracing

[Andrew Cooper <andrew.cooper3@citrix.com>]

1) vpic_ack_pending_irq() calls vlapic_accept_pic_intr() twice, once in the
   TRACE_2D() instantiation and once "for real".  Make the call only once.

2) vlapic_accept_pic_intr() similarly calls __vlapic_accept_pic_intr() twice,
   although this is more complicated to disentangle.

   v cannot be NULL because it has already been dereferenced in the function,
   causing the ternary expression to always call __vlapic_accept_pic_intr().
   However, the return expression of the function takes care to skip the call
   if this vCPU isn't the PIC target.  As __vlapic_accept_pic_intr() is far
   from trivial, make the TRACE_2D() semantics match the return semantics by
   only calling __vlapic_accept_pic_intr() when the vCPU is the PIC target.

3) hpet_set_timer() duplicates calls to hpet_tick_to_ns().  Pull the logic out
   which simplifies both the TRACE and create_periodic_time() calls.

4) lapic_rearm() makes multiple calls to vlapic_lvtt_period().  Pull it out
   into a local variable.

vlapic_accept_pic_intr() is called on every VMEntry, so this is a reduction in
VMEntry complexity across the board.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>

v2:
 * New
---
 xen/arch/x86/hvm/hpet.c   | 15 +++++++++------
 xen/arch/x86/hvm/vlapic.c | 23 +++++++++++++++--------
 xen/arch/x86/hvm/vpic.c   |  9 +++++----
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c
index ee756abb824d..475c3f8bf471 100644
--- a/xen/arch/x86/hvm/hpet.c
+++ b/xen/arch/x86/hvm/hpet.c
@@ -240,6 +240,7 @@ static void hpet_set_timer(HPETState *h, unsigned int tn,
     uint64_t tn_cmp, cur_tick, diff;
     unsigned int irq;
     unsigned int oneshot;
+    s_time_t diff_ns, period_ns = 0;
 
     ASSERT(tn < HPET_TIMER_NUM);
     ASSERT(rw_is_write_locked(&h->lock));
@@ -311,13 +312,15 @@ static void hpet_set_timer(HPETState *h, unsigned int tn,
      * status register) before another interrupt can be delivered.
      */
     oneshot = !timer_is_periodic(h, tn) || timer_level(h, tn);
+    diff_ns = hpet_tick_to_ns(h, diff);
+    if ( !oneshot )
+        period_ns = hpet_tick_to_ns(h, h->hpet.period[tn]);
+
     TRACE_2_LONG_4D(TRC_HVM_EMUL_HPET_START_TIMER, tn, irq,
-                    TRC_PAR_LONG(hpet_tick_to_ns(h, diff)),
-                    TRC_PAR_LONG(oneshot ? 0LL :
-                                 hpet_tick_to_ns(h, h->hpet.period[tn])));
-    create_periodic_time(vhpet_vcpu(h), &h->pt[tn],
-                         hpet_tick_to_ns(h, diff),
-                         oneshot ? 0 : hpet_tick_to_ns(h, h->hpet.period[tn]),
+                    TRC_PAR_LONG(diff_ns),
+                    TRC_PAR_LONG(period_ns));
+
+    create_periodic_time(vhpet_vcpu(h), &h->pt[tn], diff_ns, period_ns,
                          irq, timer_level(h, tn) ? hpet_timer_fired : NULL,
                          timer_level(h, tn) ? (void *)(unsigned long)tn : NULL,
                          timer_level(h, tn));
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 5e21fb4937d9..b8c84458ffdc 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -1267,15 +1267,18 @@ static int __vlapic_accept_pic_intr(struct vcpu *v)
 
 int vlapic_accept_pic_intr(struct vcpu *v)
 {
+    bool target, accept = false;
+
     if ( vlapic_hw_disabled(vcpu_vlapic(v)) || !has_vpic(v->domain) )
         return 0;
 
-    TRACE_2D(TRC_HVM_EMUL_LAPIC_PIC_INTR,
-             (v == v->domain->arch.hvm.i8259_target),
-             v ? __vlapic_accept_pic_intr(v) : -1);
+    target = v == v->domain->arch.hvm.i8259_target;
+    if ( target )
+        accept = __vlapic_accept_pic_intr(v);
+
+    TRACE_2D(TRC_HVM_EMUL_LAPIC_PIC_INTR, target, accept);
 
-    return ((v == v->domain->arch.hvm.i8259_target) &&
-            __vlapic_accept_pic_intr(v));
+    return target && accept;
 }
 
 void vlapic_adjust_i8259_target(struct domain *d)
@@ -1449,6 +1452,7 @@ static void lapic_rearm(struct vlapic *s)
 {
     unsigned long tmict;
     uint64_t period, tdt_msr;
+    bool is_periodic;
 
     s->pt.irq = vlapic_get_reg(s, APIC_LVTT) & APIC_VECTOR_MASK;
 
@@ -1464,12 +1468,15 @@ static void lapic_rearm(struct vlapic *s)
 
     period = ((uint64_t)APIC_BUS_CYCLE_NS *
               (uint32_t)tmict * s->hw.timer_divisor);
+    is_periodic = vlapic_lvtt_period(s);
+
     TRACE_2_LONG_3D(TRC_HVM_EMUL_LAPIC_START_TIMER, TRC_PAR_LONG(period),
-             TRC_PAR_LONG(vlapic_lvtt_period(s) ? period : 0LL), s->pt.irq);
+             TRC_PAR_LONG(is_periodic ? period : 0LL), s->pt.irq);
+
     create_periodic_time(vlapic_vcpu(s), &s->pt, period,
-                         vlapic_lvtt_period(s) ? period : 0,
+                         is_periodic ? period : 0,
                          s->pt.irq,
-                         vlapic_lvtt_period(s) ? vlapic_pt_cb : NULL,
+                         is_periodic ? vlapic_pt_cb : NULL,
                          &s->timer_last_update, false);
     s->timer_last_update = s->pt.last_plt_gtime;
 }
diff --git a/xen/arch/x86/hvm/vpic.c b/xen/arch/x86/hvm/vpic.c
index af988a868c8a..91c2c6983393 100644
--- a/xen/arch/x86/hvm/vpic.c
+++ b/xen/arch/x86/hvm/vpic.c
@@ -512,14 +512,15 @@ void vpic_irq_negative_edge(struct domain *d, int irq)
 
 int vpic_ack_pending_irq(struct vcpu *v)
 {
-    int irq;
+    int irq, accept;
     struct hvm_hw_vpic *vpic = &v->domain->arch.hvm.vpic[0];
 
     ASSERT(has_vpic(v->domain));
 
-    TRACE_2D(TRC_HVM_EMUL_PIC_PEND_IRQ_CALL, vlapic_accept_pic_intr(v),
-             vpic->int_output);
-    if ( !vlapic_accept_pic_intr(v) || !vpic->int_output )
+    accept = vlapic_accept_pic_intr(v);
+
+    TRACE_2D(TRC_HVM_EMUL_PIC_PEND_IRQ_CALL, accept, vpic->int_output);
+    if ( !accept || !vpic->int_output )
         return -1;
 
     irq = vpic_intack(vpic);
-- 
2.11.0