Hi,

Following patch fixed hvm KASSERT issue for me.  Not have a
concrete scenario when or how the race condition broke.

However, the related issue, slow hvm is not solved yet.
When I use WinXP with recent kernel, I feel it is much
slower than 4.99.18.  I feel something like below.
e.g. 4.99.21 Xen3.1.0 took 30 sec to open empty start menu.

4.99.18 Xen3.0.4 hvm WinXP(4/30 source)          base 1x slow
4.99.20 Xen3.0.4 hvm WinXP(5/18 src with this patch)  5x slow
4.99.21 Xen3.0.4 hvm WinXP(6/24 src with this patch)  5x slow
4.99.21 Xen3.1.0 hvm WinXP(6/24 src with this patch)  20x slow

-- Kazushi

Index: arch/xen/i386/locore.S
===================================================================
RCS file: /cvsroot/src/sys/arch/xen/i386/locore.S,v
retrieving revision 1.25
diff -u -r1.25 locore.S
--- arch/xen/i386/locore.S	17 May 2007 14:51:35 -0000	1.25
+++ arch/xen/i386/locore.S	26 Jun 2007 16:39:08 -0000
@@ -659,6 +659,8 @@
 
 switch_skipsave:
 
+	CLI(%ebx)
+
 	/*
 	 * Switch to newlwp's stack.
 	 */
@@ -681,6 +683,8 @@
 
 	movl	$0,CPUVAR(RESCHED)
 
+	STI(%ebx)
+
 	/*
 	 *  Check for restartable atomic sequences (RAS)
 	 */

On a paper submitted by a physicist colleague:

This isn't right.  This isn't even wrong.
		-- Wolfgang Pauli