[Xen-devel] [PATCH RFC 1/3] x86/vpt: execute callbacks for masked interrupts

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Execute periodic_time callbacks even if the interrupt is not actually
injected because the IRQ is masked.

Current callbacks from emulated timer devices only update emulated
registers, which from my reading of the specs should happen regardless
of whether the interrupt has been injected or not.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Stefan Bader <stefan.bader@xxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/vpt.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/vpt.c b/xen/arch/x86/hvm/vpt.c
index 181f4cb631..1a24fbaa44 100644
--- a/xen/arch/x86/hvm/vpt.c
+++ b/xen/arch/x86/hvm/vpt.c
@@ -247,9 +247,31 @@ static void pt_timer_fn(void *data)
     pt_unlock(pt);
 }
 
+static void execute_callbacks(struct vcpu *v, struct list_head *tm)
+{
+    spin_lock(&v->arch.hvm_vcpu.tm_lock);
+    while ( !list_empty(tm) )
+    {
+        struct periodic_time *pt = list_first_entry(tm, struct periodic_time,
+                                                    list);
+        time_cb *cb = pt->cb;
+        void *cb_priv = pt->priv;
+
+        list_del(&pt->list);
+        pt->on_list = 0;
+        spin_unlock(&v->arch.hvm_vcpu.tm_lock);
+
+        cb(v, cb_priv);
+
+        spin_lock(&v->arch.hvm_vcpu.tm_lock);
+    }
+    spin_unlock(&v->arch.hvm_vcpu.tm_lock);
+}
+
 int pt_update_irq(struct vcpu *v)
 {
     struct list_head *head = &v->arch.hvm_vcpu.tm_list;
+    LIST_HEAD(purged);
     struct periodic_time *pt, *temp, *earliest_pt;
     uint64_t max_lag;
     int irq, is_lapic, pt_vector;
@@ -267,7 +289,10 @@ int pt_update_irq(struct vcpu *v)
             {
                 /* suspend timer emulation */
                 list_del(&pt->list);
-                pt->on_list = 0;
+                if ( pt->cb )
+                    list_add(&pt->list, &purged);
+                else
+                    pt->on_list = 0;
             }
             else
             {
@@ -283,6 +308,7 @@ int pt_update_irq(struct vcpu *v)
     if ( earliest_pt == NULL )
     {
         spin_unlock(&v->arch.hvm_vcpu.tm_lock);
+        execute_callbacks(v, &purged);
         return -1;
     }
 
@@ -292,6 +318,8 @@ int pt_update_irq(struct vcpu *v)
 
     spin_unlock(&v->arch.hvm_vcpu.tm_lock);
 
+    execute_callbacks(v, &purged);
+
     /*
      * If periodic timer interrut is handled by lapic, its vector in
      * IRR is returned and used to set eoi_exit_bitmap for virtual
-- 
2.16.1


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