arm64: smp: Handle errors reported by the firmware

BugLink: https://bugs.launchpad.net/bugs/1855313

[ Upstream commit f357b3a7 ]

The __cpu_up() routine ignores the errors reported by the firmware
for a CPU bringup operation and looks for the error status set by the
booting CPU. If the CPU never entered the kernel, we could end up
in assuming stale error status, which otherwise would have been
set/cleared appropriately by the booting CPU.
Reported-by: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/arm64/kernel/smp.c

@@ -117,6 +117,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 		}
 	} else {
 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
+		return ret;
 	}
 
 	secondary_data.stack = NULL;