MIPS: Add function get_ebase_cpunum

This returns the CPUNum from the low order Ebase bits.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7012/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mipsregs.h

@@ -1792,6 +1792,15 @@ __BUILD_SET_C0(brcm_cmt_ctrl)
 __BUILD_SET_C0(brcm_config)
 __BUILD_SET_C0(brcm_mode)
 
+/*
+ * Return low 10 bits of ebase.
+ * Note that under KVM (MIPSVZ) this returns vcpu id.
+ */
+static inline unsigned int get_ebase_cpunum(void)
+{
+	return read_c0_ebase() & 0x3ff;
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_MIPSREGS_H */

arch/mips/kernel/cpu-probe.c

@@ -423,7 +423,7 @@ static void decode_configs(struct cpuinfo_mips *c)
 
 #ifndef CONFIG_MIPS_CPS
 	if (cpu_has_mips_r2) {
-		c->core = read_c0_ebase() & 0x3ff;
+		c->core = get_ebase_cpunum();
 		if (cpu_has_mipsmt)
 			c->core >>= fls(core_nvpes()) - 1;
 	}