x86/hvm: don't force vCPU 0 for IRQ 0 when using fixed destination mode

When the IO APIC pin mapped to the ISA IRQ 0 has been configured to
use fixed delivery mode, do not forcefully route interrupts to vCPU 0,
as the OS might have setup those interrupts to be injected to a
different vCPU, and injecting to vCPU 0 can cause the OS to miss such
interrupts or errors to happen due to unexpected vectors being
injected on vCPU 0.

In order to fix remove such handling altogether for fixed destination
mode pins and just inject them according to the data setup in the
IO-APIC entry.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index b00037ea874a9fe1a3c357322a9aa59c5567c98c..123191db75aa81b4a0a933f1d8c321584c8975c4 100644 (file)
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -438,26 +438,11 @@ static void vioapic_deliver(struct hvm_vioapic *vioapic, unsigned int pin)
     }
 
     case dest_Fixed:
-    {
-#ifdef IRQ0_SPECIAL_ROUTING
-        /* Do not deliver timer interrupts to VCPU != 0 */
-        if ( (irq == hvm_isa_irq_to_gsi(0)) && pt_active(&d->arch.vpit.pt0) )
-        {
-            if ( (v = d->vcpu ? d->vcpu[0] : NULL) != NULL )
-                ioapic_inj_irq(vioapic, vcpu_vlapic(v), vector,
-                               trig_mode, delivery_mode);
-        }
-        else
-#endif
-        {
-            for_each_vcpu ( d, v )
-                if ( vlapic_match_dest(vcpu_vlapic(v), NULL,
-                                       0, dest, dest_mode) )
-                    ioapic_inj_irq(vioapic, vcpu_vlapic(v), vector,
-                                   trig_mode, delivery_mode);
-        }
+        for_each_vcpu ( d, v )
+            if ( vlapic_match_dest(vcpu_vlapic(v), NULL, 0, dest, dest_mode) )
+                ioapic_inj_irq(vioapic, vcpu_vlapic(v), vector, trig_mode,
+                               delivery_mode);
         break;
-    }
 
     case dest_NMI:
     {