From: Tetsu Yamamoto <tyamamot@redhat.com>
Date: Wed, 16 Apr 2008 11:08:07 -0400
Subject: [xen] ia64: set memory attribute in inline asm
Message-id: 48061657.7090806@redhat.com
O-Subject: [RHEL5.2][PATCH] ia64-xen: set memory attribute in inline asm
Bugzilla: 426015

This is an additional patch for BZ#426015

- [xen-ia64] Dom0 panic while we run ftp test tool between HVM and Dom0.
https://bugzilla.redhat.com/show_bug.cgi?id=426015

[Description]
Inline assembler code for ssm instruction did not have 'memory'
attribute.  In that case, a compiler optimizes the code and generates
unintented assembler code.  This problem affect the ftp stress test
between Dom0/HVM.  This patch fix it by adding 'memory' attribute to
inline assmbler code to avoid the compiler optimization.  Besides that,
this patch removes XEN_HYPER_GET_IVR which is wrong (does not return any
value) and never used.

Unfortunately, this patch can not yet fix the ftp problem completely,
but it makes some improvement; running time for ftp test is improved
from 3days to 4 days.

[Upstream Status]
Committed in the ia64 tree:
- [IA64] Set memory attribute in inline asm
http://xenbits.xensource.com/ext/ia64/linux-2.6.18-xen.hg?rev/dbe8a35dcaf7

The backported patch has only the part relevant to RHEL5 kernel.

[brew ID]
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1272787

[Test Status]
Run ftp stress test between Dom0 and HVM domain.  The time Dom0 can run
without panic is:
 w/o patch: 3 days
 w/  patch: 4 days

Please review and ACK.

Regards,

Tetsu Yamamoto

Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Jarod Wilson <jwilson@redhat.com>

diff --git a/include/asm-ia64/xen/privop.h b/include/asm-ia64/xen/privop.h
index 1bee5ef..b7a2bca 100644
--- a/include/asm-ia64/xen/privop.h
+++ b/include/asm-ia64/xen/privop.h
@@ -64,8 +64,7 @@
 #endif
 
 #ifndef __ASSEMBLY__
-#define	XEN_HYPER_SSM_I		asm("break %0" : : "i" (HYPERPRIVOP_SSM_I))
-#define	XEN_HYPER_GET_IVR	asm("break %0" : : "i" (HYPERPRIVOP_GET_IVR))
+#define	XEN_HYPER_SSM_I		asm ("break %0" : : "i" (HYPERPRIVOP_SSM_I) : "memory")
 
 /************************************************/
 /* Instructions paravirtualized for correctness */