[Xen-devel] [PATCH] ioemu: fix INTx disable bit in MSI-INTx translation

[Qing He <qing.he@xxxxxxxxx>]

Fix the bug introduced in commit 8c771eb6: when msi-intx
translation is enabled, int disable bit in PCI_COMMAND is set.
This approach has two issues:
    1. for some (buggy) devices, set INTx bit will also disable
       MSI so that MSI doesn't work any more.
    2. it's never re-enabled when msi translation is turned off.
       If the guest uses INTx, it can't receive any interrupts
       from then.

This patch leaves INTx disable bit unset if MSI-INTx translation
is used.

Signed-off-by: Qing He <qing.he@xxxxxxxxx>
---
diff --git a/hw/pass-through.c b/hw/pass-through.c
index 95b4a47..d16f177 100644
--- a/hw/pass-through.c
+++ b/hw/pass-through.c
@@ -3769,9 +3769,11 @@ static struct pt_dev * register_real_device(PCIBus 
*e_bus,
 
     /* setup MSI-INTx translation if support */
     rc = pt_enable_msi_translate(assigned_device);
+    if (rc == 0)
+        goto out;
 
     /* bind machine_irq to device */
-    if (rc < 0 && machine_irq != 0)
+    if (machine_irq != 0)
     {
         e_device = (assigned_device->dev.devfn >> 3) & 0x1f;
         /* fix virtual interrupt pin to INTA# */

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