mips/kvm: Implement PRid CP0 register

Implement saving and restoring to KVM state of the Processor ID (PRid)
CP0 register. This allows QEMU to control the PRid exposed to the guest
instead of using the default set by KVM.
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Reviewed-by: NLeon Alrae <leon.alrae@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NLeon Alrae <leon.alrae@imgtec.com>

target-mips/kvm.c

@@ -228,6 +228,7 @@ int kvm_mips_set_ipi_interrupt(MIPSCPU *cpu, int irq, int level)
 #define KVM_REG_MIPS_CP0_STATUS         MIPS_CP0_32(12, 0)
 #define KVM_REG_MIPS_CP0_CAUSE          MIPS_CP0_32(13, 0)
 #define KVM_REG_MIPS_CP0_EPC            MIPS_CP0_64(14, 0)
+#define KVM_REG_MIPS_CP0_PRID           MIPS_CP0_32(15, 0)
 #define KVM_REG_MIPS_CP0_ERROREPC       MIPS_CP0_64(30, 0)
 
 static inline int kvm_mips_put_one_reg(CPUState *cs, uint64_t reg_id,
@@ -520,6 +521,11 @@ static int kvm_mips_put_cp0_registers(CPUState *cs, int level)
         DPRINTF("%s: Failed to put CP0_EPC (%d)\n", __func__, err);
         ret = err;
     }
+    err = kvm_mips_put_one_reg(cs, KVM_REG_MIPS_CP0_PRID, &env->CP0_PRid);
+    if (err < 0) {
+        DPRINTF("%s: Failed to put CP0_PRID (%d)\n", __func__, err);
+        ret = err;
+    }
     err = kvm_mips_put_one_ulreg(cs, KVM_REG_MIPS_CP0_ERROREPC,
                                  &env->CP0_ErrorEPC);
     if (err < 0) {
@@ -606,6 +612,11 @@ static int kvm_mips_get_cp0_registers(CPUState *cs)
         DPRINTF("%s: Failed to get CP0_EPC (%d)\n", __func__, err);
         ret = err;
     }
+    err = kvm_mips_get_one_reg(cs, KVM_REG_MIPS_CP0_PRID, &env->CP0_PRid);
+    if (err < 0) {
+        DPRINTF("%s: Failed to get CP0_PRID (%d)\n", __func__, err);
+        ret = err;
+    }
     err = kvm_mips_get_one_ulreg(cs, KVM_REG_MIPS_CP0_ERROREPC,
                                  &env->CP0_ErrorEPC);
     if (err < 0) {