[Xen-devel] [PATCH] 32on64: increase size of compat argument translation area to 2 pages

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1246625635 -3600
# Node ID cb45d91651df9b27d01a807a2be40e8a3460876f
# Parent  31002ac6a13caadab7c163d387af558a2b2da7ce
32on64: increase size of compat argument translation area to 2 pages.

The existing single page is not quite large enough to translate a
XENMEM_exchange hypercall with order=9. Since Linux uses
MAX_CONTIG_ORDER of 9 this seems like a reasonable upper bound to
support.

Increasing COMPAT_ARG_XLAT_SIZE to 2 pages is sufficient to support
order 9 exchanges. PERCPU_SHIFT must also be increased since the
translation area is percpu.

This was observed through a driver which did a large
pci_alloc_consistent request.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 31002ac6a13c -r cb45d91651df xen/include/asm-x86/percpu.h
--- a/xen/include/asm-x86/percpu.h      Thu Jul 02 09:43:41 2009 +0100
+++ b/xen/include/asm-x86/percpu.h      Fri Jul 03 13:53:55 2009 +0100
@@ -1,7 +1,7 @@
 #ifndef __X86_PERCPU_H__
 #define __X86_PERCPU_H__
 
-#define PERCPU_SHIFT 13
+#define PERCPU_SHIFT 14
 #define PERCPU_SIZE  (1UL << PERCPU_SHIFT)
 
 /* Separate out the type, so (int[3], foo) works. */
diff -r 31002ac6a13c -r cb45d91651df xen/include/asm-x86/x86_64/uaccess.h
--- a/xen/include/asm-x86/x86_64/uaccess.h      Thu Jul 02 09:43:41 2009 +0100
+++ b/xen/include/asm-x86/x86_64/uaccess.h      Fri Jul 03 13:53:55 2009 +0100
@@ -2,7 +2,7 @@
 #define __X86_64_UACCESS_H
 
 #define COMPAT_ARG_XLAT_VIRT_BASE this_cpu(compat_arg_xlat)
-#define COMPAT_ARG_XLAT_SIZE      PAGE_SIZE
+#define COMPAT_ARG_XLAT_SIZE      2*PAGE_SIZE
 DECLARE_PER_CPU(char, compat_arg_xlat[COMPAT_ARG_XLAT_SIZE]);
 #define is_compat_arg_xlat_range(addr, size) ({                               \
     unsigned long __off;                                                      \

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