MIPS: CM, CPC: Ensure core-other GCRs reflect the correct core

Ensure the update to which core the core-other GCR regions reflect has
taken place before any core-other GCRs are accessed by placing a memory
barrier (sync instruction) between the write to the core-other registers
and any such GCR accesses.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11209/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/mips-cm.c

@@ -278,6 +278,12 @@ void mips_cm_lock_other(unsigned int core, unsigned int vp)
 	}
 
 	write_gcr_cl_other(val);
+
+	/*
+	 * Ensure the core-other region reflects the appropriate core &
+	 * VP before any accesses to it occur.
+	 */
+	mb();
 }
 
 void mips_cm_unlock_other(void)

arch/mips/kernel/mips-cpc.c

@@ -76,6 +76,12 @@ void mips_cpc_lock_other(unsigned int core)
 	spin_lock_irqsave(&per_cpu(cpc_core_lock, curr_core),
 			  per_cpu(cpc_core_lock_flags, curr_core));
 	write_cpc_cl_other(core << CPC_Cx_OTHER_CORENUM_SHF);
+
+	/*
+	 * Ensure the core-other region reflects the appropriate core &
+	 * VP before any accesses to it occur.
+	 */
+	mb();
 }
 
 void mips_cpc_unlock_other(void)