linux-kernel - [PATCH v3 2/2] arm64: Document ICC_CTLR

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Message-Id: <20191002090613.14236-3-maz@kernel.org>
Date:   Wed,  2 Oct 2019 10:06:13 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        huawei.libin@...wei.com, uohanjun@...wei.com, liwei391@...wei.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/2] arm64: Document ICC_CTLR_EL3.PMHE setting requirements

It goes without saying, but better saying it: the kernel expects
ICC_CTLR_EL3.PMHE to have the same value across all CPUs, and
for that setting not to change during the lifetime of the kernel.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 Documentation/arm64/booting.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst
index d3f3a60fbf25..5d78a6f5b0ae 100644
--- a/Documentation/arm64/booting.rst
+++ b/Documentation/arm64/booting.rst
@@ -213,6 +213,9 @@ Before jumping into the kernel, the following conditions must be met:
 
       - ICC_SRE_EL3.Enable (bit 3) must be initialiased to 0b1.
       - ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b1.
+      - ICC_CTLR_EL3.PMHE (bit 6) must be set to the same value across
+        all CPUs the kernel is executing on, and must stay constant
+        for the lifetime of the kernel.
 
   - If the kernel is entered at EL1:
 
-- 
2.20.1