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>

3 files changed, 23 insertions, 2 deletions

diff --git a/arch/mips/include/asm/mach-generic/spaces.h b/arch/mips/include/asm/mach-generic/spaces.h
index 73d717a75cb0..5b2f2e68e57f 100644
--- a/arch/mips/include/asm/mach-generic/spaces.h
+++ b/arch/mips/include/asm/mach-generic/spaces.h
@@ -20,14 +20,21 @@
 #endif
 
 #ifdef CONFIG_32BIT
-
+#ifdef CONFIG_KVM_GUEST
+#define CAC_BASE                _AC(0x40000000, UL)
+#else
 #define CAC_BASE                _AC(0x80000000, UL)
+#endif
 #define IO_BASE                 _AC(0xa0000000, UL)
 #define UNCAC_BASE              _AC(0xa0000000, UL)
 
 #ifndef MAP_BASE
+#ifdef CONFIG_KVM_GUEST
+#define MAP_BASE                _AC(0x60000000, UL)
+#else
 #define MAP_BASE                _AC(0xc0000000, UL)
 #endif
+#endif
 
 /*
  * Memory above this physical address will be considered highmem.
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 2a5fa7abb346..71686c897dea 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -44,11 +44,16 @@ extern unsigned int vced_count, vcei_count;
 #define SPECIAL_PAGES_SIZE PAGE_SIZE
 
 #ifdef CONFIG_32BIT
+#ifdef CONFIG_KVM_GUEST
+/* User space process size is limited to 1GB in KVM Guest Mode */
+#define TASK_SIZE       0x3fff8000UL
+#else
 /*
  * User space process size: 2GB. This is hardcoded into a few places,
  * so don't change it unless you know what you are doing.
  */
 #define TASK_SIZE       0x7fff8000UL
+#endif
 
 #ifdef __KERNEL__
 #define STACK_TOP_MAX   TASK_SIZE
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index bd87e36bf26a..b46caab453a5 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 @@ extern u64 __ua_limit;
  * 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