commit 9843b030cc951bce4a4d9bec38b5155c96eb1740
author Sanjay Lal <sanjayl@kymasys.com> Wed Nov 21 18:34:03 2012 -0800
committer Ralf Baechle <ralf@linux-mips.org> Wed May 08 03:55:35 2013 +0200
tree dd219e76dce1e1b92e6f5fc19e8767b60827c7ee
parent 669e846e6c4e13f16d7418973609931e362cb16a

KVM/MIPS32: KVM Guest kernel support.

Both Guest kernel and Guest Userspace execute in UM. The memory map is as follows:
Guest User address space:   0x00000000 -> 0x40000000
Guest Kernel Unmapped:      0x40000000 -> 0x60000000
Guest Kernel Mapped:        0x60000000 -> 0x80000000
- Guest Usermode virtual memory is limited to 1GB.

Signed-off-by: Sanjay Lal <sanjayl@kymasys.com>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/uaccess.h

diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index bd87e36..b46caab 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -23,7 +23,11 @@
  */
 #ifdef CONFIG_32BIT
 
-#define __UA_LIMIT	0x80000000UL
+#ifdef CONFIG_KVM_GUEST
+#define __UA_LIMIT 0x40000000UL
+#else
+#define __UA_LIMIT 0x80000000UL
+#endif
 
 #define __UA_ADDR	".word"
 #define __UA_LA		"la"
@@ -55,8 +59,13 @@
  * address in this range it's the process's problem, not ours :-)
  */
 
+#ifdef CONFIG_KVM_GUEST
+#define KERNEL_DS	((mm_segment_t) { 0x80000000UL })
+#define USER_DS		((mm_segment_t) { 0xC0000000UL })
+#else
 #define KERNEL_DS	((mm_segment_t) { 0UL })
 #define USER_DS		((mm_segment_t) { __UA_LIMIT })
+#endif
 
 #define VERIFY_READ    0
 #define VERIFY_WRITE   1