hw/mips: Add API to convert KVM guest KSEG0 <-> GPA

Add API for converting physical addresses to KVM guest KSEG0 addresses,
and fix the existing API for converting KSEG0 addresses to physical
addresses to work in the KVM case. Both have the same sized KSEG0, so
it's just a case of fixing the mask.

In KVM trap and emulate mode both the guest kernel and guest userspace
execute in useg:
    Guest User address space:   0x00000000..0x3fffffff
    Guest Kernel Unmapped:      0x40000000..0x5fffffff
    Guest Kernel Mapped:        0x60000000..0x7fffffff
Signed-off-by: NSanjay Lal <sanjayl@kymasys.com>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/mips/addr.c

@@ -25,10 +25,15 @@
 
 uint64_t cpu_mips_kseg0_to_phys(void *opaque, uint64_t addr)
 {
-    return addr & 0x7fffffffll;
+    return addr & 0x1fffffffll;
 }
 
 uint64_t cpu_mips_phys_to_kseg0(void *opaque, uint64_t addr)
 {
     return addr | ~0x7fffffffll;
 }
+
+uint64_t cpu_mips_kvm_um_phys_to_kseg0(void *opaque, uint64_t addr)
+{
+    return addr | 0x40000000ll;
+}

include/hw/mips/cpudevs.h

@@ -5,6 +5,8 @@
 /* mips_addr.c */
 uint64_t cpu_mips_kseg0_to_phys(void *opaque, uint64_t addr);
 uint64_t cpu_mips_phys_to_kseg0(void *opaque, uint64_t addr);
+uint64_t cpu_mips_kvm_um_phys_to_kseg0(void *opaque, uint64_t addr);
+
 
 /* mips_int.c */
 void cpu_mips_irq_init_cpu(CPUMIPSState *env);