FAILED: patch "[PATCH] arm64: Avoid Cavium TX2 erratum 219 when switching TTBR" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9405447ef79bc93101373e130f72e9e6cbf17dbb Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@kernel.org>
Date: Tue, 9 Apr 2019 16:22:24 +0100
Subject: [PATCH] arm64: Avoid Cavium TX2 erratum 219 when switching TTBR

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@vger.kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index e81e0cbd728f..ac1dbca3d0cd 100644
--- 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 */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index d999ca2dd760..a19bb3e4bcfb 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -884,6 +884,11 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		ERRATA_MIDR_RANGE_LIST(tx2_family_cpus),
 		.matches = needs_tx2_tvm_workaround,
 	},
+	{
+		.desc = "Cavium ThunderX2 erratum 219 (PRFM removal)",
+		.capability = ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM,
+		ERRATA_MIDR_RANGE_LIST(tx2_family_cpus),
+	},
 #endif
 	{
 	}
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 84a822748c84..109894bd3194 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1070,7 +1070,9 @@ alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
 #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