[PATCH] arm64: Allow CPUs unffected by ARM erratum 1418040 to come in late

From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
	kernel-team@android.com, Will Deacon <will@kernel.org>,
	Doug Anderson <dianders@google.com>
Subject: [PATCH] arm64: Allow CPUs unffected by ARM erratum 1418040 to come in late
Date: Fri, 11 Sep 2020 19:16:11 +0100	[thread overview]
Message-ID: <20200911181611.2073183-1-maz@kernel.org> (raw)

Now that we allow CPUs affected by erratum 1418040 to come in late,
this prevents their unaffected sibblings from coming in late (or
coming back after a suspend or hotplug-off, which amounts to the
same thing).

To allow this, we need to add ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU,
which amounts to set .type to ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE.

Reported-by: Doug Anderson <dianders@google.com>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Fixes: bf87bb0881d0 ("arm64: Allow booting of late CPUs affected by erratum 1418040")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kernel/cpu_errata.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index c332d49780dc..560ba69e13c1 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -910,8 +910,12 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.desc = "ARM erratum 1418040",
 		.capability = ARM64_WORKAROUND_1418040,
 		ERRATA_MIDR_RANGE_LIST(erratum_1418040_list),
-		.type = (ARM64_CPUCAP_SCOPE_LOCAL_CPU |
-			 ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU),
+		/*
+		 * We need to allow affected CPUs to come in late, but
+		 * also need the non-affected CPUs to be able to come
+		 * in at any point in time. Wonderful.
+		 */
+		.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
 	},
 #endif
 #ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_AT
-- 
2.28.0


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