[PATCH] pvops: Avoid re-alloc_intr_gate of hvm evtchn callback

[Frank Pan <frankpzh@gmail.com>]

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I've met a issue that a PV-on-HVM domain become stucked after migration.
The alloc_intr_gate(HVM_XEN_EVTCHN_CALLBACK) is called the second time
after the migration and leads to BUG(). (The first time is at system
initialization)

The following patch fixes this by check whether this callback is
registered or not before calling alloc_intr_gate.
---
 linux-2.6-xen/drivers/xen/events.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/linux-2.6-xen/drivers/xen/events.c
b/linux-2.6-xen/drivers/xen/events.c
index ac7b42f..77ffceb 100644
--- a/linux-2.6-xen/drivers/xen/events.c
+++ b/linux-2.6-xen/drivers/xen/events.c
@@ -1500,7 +1500,9 @@ void xen_callback_vector(void)
 		}
 		printk(KERN_INFO "Xen HVM callback vector for event delivery is "
 				"enabled\n");
-		alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
+		/* xen_callback_vector will be called after every domU resume */
+		if (!test_bit(XEN_HVM_EVTCHN_CALLBACK, used_vectors))
+			alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
 	}
 }
 #else
-- 
1.7.0.4


-- 
潘震皓, Frank Pan

Computer Science and Technology
Tsinghua University

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From dc04b1fbddbc428bb1453187a69be88a036a5d1e Mon Sep 17 00:00:00 2001
From: Frank Pan <frankpzh@gmail.com>
Date: Sat, 5 Mar 2011 16:16:45 +0800
Subject: [PATCH] Avoid re-alloc_intr_gate of hvm evtchn callback

I've met a issue that a PV-on-HVM domain become stucked after migration.
The alloc_intr_gate(HVM_XEN_EVTCHN_CALLBACK) is called the second time after the migration and leads to BUG(). (The first time is at system initialization)

The following patch fixes this by check whether this callback is registered or not before calling alloc_intr_gate.
---
 linux-2.6-xen/drivers/xen/events.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/linux-2.6-xen/drivers/xen/events.c b/linux-2.6-xen/drivers/xen/events.c
index ac7b42f..77ffceb 100644
--- a/linux-2.6-xen/drivers/xen/events.c
+++ b/linux-2.6-xen/drivers/xen/events.c
@@ -1500,7 +1500,9 @@ void xen_callback_vector(void)
 		}
 		printk(KERN_INFO "Xen HVM callback vector for event delivery is "
 				"enabled\n");
-		alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
+		/* xen_callback_vector will be called after every domU resume */
+		if (!test_bit(XEN_HVM_EVTCHN_CALLBACK, used_vectors))
+			alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
 	}
 }
 #else
-- 
1.7.0.4


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