[Xen-devel] [PATCH 1/2] passthrough: allow pt_bind_irq for msi update

[Qing He <qing.he@xxxxxxxxx>]

This patch extends pt_bind_irq to handle the update of msi guest
vector and flag.

Unbind and rebind using separate hypercalls may not be viable sometime.
For example, the guest may update MSI address/data on fly without
disabling it first (e.g. change delivery/destination), implement these
updates in such a way may result in interrupt loss.

Signed-off-by: Qing He <qing.he@xxxxxxxxx>
---
diff -r accf139b2eb9 xen/drivers/passthrough/io.c
--- a/xen/drivers/passthrough/io.c      Mon Apr 06 21:12:33 2009 +0100
+++ b/xen/drivers/passthrough/io.c      Wed Apr 15 17:22:11 2009 +0800
@@ -148,12 +148,23 @@
                 return rc;
             }
         }
-        else if (hvm_irq_dpci->mirq[pirq].gmsi.gvec != pt_irq_bind->u.msi.gvec
-                ||hvm_irq_dpci->msi_gvec_pirq[pt_irq_bind->u.msi.gvec] != pirq)
+        else
+        {
+            uint32_t mask = HVM_IRQ_DPCI_MACH_MSI | HVM_IRQ_DPCI_GUEST_MSI;
+            uint32_t old_gvec;
 
-        {
-            spin_unlock(&d->event_lock);
-            return -EBUSY;
+            if ( (hvm_irq_dpci->mirq[pirq].flags & mask) != mask)
+            {
+                   spin_unlock(&d->event_lock);
+                   return -EBUSY;
+            }
+ 
+            /* if pirq is already mapped as vmsi, update the guest data/addr */
+            old_gvec = hvm_irq_dpci->mirq[pirq].gmsi.gvec;
+            hvm_irq_dpci->msi_gvec_pirq[old_gvec] = 0;
+            hvm_irq_dpci->mirq[pirq].gmsi.gvec = pt_irq_bind->u.msi.gvec;
+            hvm_irq_dpci->mirq[pirq].gmsi.gflags = pt_irq_bind->u.msi.gflags;
+            hvm_irq_dpci->msi_gvec_pirq[pt_irq_bind->u.msi.gvec] = pirq;
         }
     }
     else

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