From: James Morse <james.morse@arm.com>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu
Cc: Suzuki K Pouloze <suzuki.poulose@arm.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Julien Thierry <julien.thierry@arm.com>,
Will Deacon <will.deacon@arm.com>,
James Morse <james.morse@arm.com>
Subject: [PATCH v3 1/6] arm64: assembler: Switch ESB-instruction with a vanilla nop if !ARM64_HAS_RAS
Date: Tue, 18 Jun 2019 16:17:33 +0100 [thread overview]
Message-ID: <20190618151738.258983-2-james.morse@arm.com> (raw)
In-Reply-To: <20190618151738.258983-1-james.morse@arm.com>
The ESB-instruction is a nop on CPUs that don't implement the RAS
extensions. This lets us use it in places like the vectors without
having to use alternatives.
If someone disables CONFIG_ARM64_RAS_EXTN, this instruction still has
its RAS extensions behaviour, but we no longer read DISR_EL1 as this
register does depend on alternatives.
This could go wrong if we want to synchronize an SError from a KVM
guest. On a CPU that has the RAS extensions, but the KConfig option
was disabled, we consume the pending SError with no chance of ever
reading it.
Hide the ESB-instruction behind the CONFIG_ARM64_RAS_EXTN option,
outputting a regular nop if the feature has been disabled.
Reported-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
New for v2. The esb where this would be a problem is added later in
this series, but there is no build-dependency.
---
arch/arm64/include/asm/assembler.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 92b6b7cf67dd..2d2114b39846 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -107,7 +107,11 @@
* RAS Error Synchronization barrier
*/
.macro esb
+#ifdef CONFIG_ARM64_RAS_EXTN
hint #16
+#else
+ nop
+#endif
.endm
/*
--
2.20.1
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next prev parent reply other threads:[~2019-06-18 15:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 15:17 [PATCH v3 0/6] KVM: arm64: Account host/guest SError more precisely (Neoverse-N1 #1349291) James Morse
2019-06-18 15:17 ` James Morse [this message]
2019-06-18 15:17 ` [PATCH v3 2/6] KVM: arm64: Abstract the size of the HYP vectors pre-amble James Morse
2019-06-18 15:17 ` [PATCH v3 3/6] KVM: arm64: Make indirect vectors preamble behaviour symmetric James Morse
2019-06-18 15:17 ` [PATCH v3 4/6] KVM: arm64: Consume pending SError as early as possible James Morse
2019-06-18 15:17 ` [PATCH v3 5/6] KVM: arm64: Defer guest entry when an asynchronous exception is pending James Morse
2019-06-18 15:17 ` [PATCH v3 6/6] arm64: Update silicon-errata.txt for Neoverse-N1 #1349291 James Morse
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