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, 14 insertions, 1 deletions

diff --git a/arch/mips/kernel/binfmt_elfo32.c b/arch/mips/kernel/binfmt_elfo32.c
index 556a4357d7fc..97c5a1668e53 100644
--- a/arch/mips/kernel/binfmt_elfo32.c
+++ b/arch/mips/kernel/binfmt_elfo32.c
@@ -48,7 +48,11 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
         __res;                                                          \
 })
 
+#ifdef CONFIG_KVM_GUEST
+#define TASK32_SIZE             0x3fff8000UL
+#else
 #define TASK32_SIZE             0x7fff8000UL
+#endif
 #undef ELF_ET_DYN_BASE
 #define ELF_ET_DYN_BASE         (TASK32_SIZE / 3 * 2)
 
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 07b847d77f5d..fd75d7144524 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -118,6 +118,10 @@ int c0_compare_int_usable(void)
         unsigned int delta;
         unsigned int cnt;
 
+#ifdef CONFIG_KVM_GUEST
+    return 1;
+#endif
+
         /*
          * IP7 already pending?  Try to clear it by acking the timer.
          */
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index a200b5bdbb87..59351e5d0591 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1713,7 +1713,12 @@ void __init trap_init(void)
                 ebase = (unsigned long)
                         __alloc_bootmem(size, 1 << fls(size), 0);
         } else {
-                ebase = CKSEG0;
+#ifdef CONFIG_KVM_GUEST
+#define KVM_GUEST_KSEG0     0x40000000
+        ebase = KVM_GUEST_KSEG0;
+#else
+        ebase = CKSEG0;
+#endif
                 if (cpu_has_mips_r2)
                         ebase += (read_c0_ebase() & 0x3ffff000);
         }