linux-kernel - [PATCH 5.3 164/197] arm64: Avoid Cavium TX2 erratum 219 when switching TTBR

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Message-Id: <20191027203402.902355511@linuxfoundation.org>
Date:   Sun, 27 Oct 2019 22:01:22 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will@...nel.org>
Subject: [PATCH 5.3 164/197] arm64: Avoid Cavium TX2 erratum 219 when switching TTBR

From: Marc Zyngier <marc.zyngier@....com>

commit 9405447ef79bc93101373e130f72e9e6cbf17dbb upstream.

As a PRFM instruction racing against a TTBR update can have undesirable
effects on TX2, NOP-out such PRFM on cores that are affected by
the TX2-219 erratum.

Cc: <stable@...r.kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/include/asm/cpucaps.h |    3 ++-
 arch/arm64/kernel/cpu_errata.c   |    5 +++++
 arch/arm64/kernel/entry.S        |    2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -53,7 +53,8 @@
 #define ARM64_HAS_DCPODP			43
 #define ARM64_WORKAROUND_1463225		44
 #define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM	45
+#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
 
-#define ARM64_NCAPS				46
+#define ARM64_NCAPS				47
 
 #endif /* __ASM_CPUCAPS_H */
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -851,6 +851,11 @@ const struct arm64_cpu_capabilities arm6
 		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
 		.matches = has_cortex_a76_erratum_1463225,
 	},
+	{
+		.desc = "Cavium ThunderX2 erratum 219 (PRFM removal)",
+		.capability = ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM,
+		ERRATA_MIDR_RANGE_LIST(tx2_family_cpus),
+	},
 #endif
 	{
 	}
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1070,7 +1070,9 @@ alternative_insn isb, nop, ARM64_WORKARO
 #else
 	ldr	x30, =vectors
 #endif
+alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
 	prfm	plil1strm, [x30, #(1b - tramp_vectors)]
+alternative_else_nop_endif
 	msr	vbar_el1, x30
 	add	x30, x30, #(1b - tramp_vectors)
 	isb