From 6dabf1fac6b48d256b1d78b81c9356a88df26d2f Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Mon, 16 Jan 2023 16:04:37 +0000 Subject: [PATCH] arm64: Document boot requirements for SME 2 SME 2 introduces the new ZT0 register, we require that access to this reigster is not trapped when we identify that the feature is supported. Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-2-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas --- Documentation/arm64/booting.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst index 96fe10e..f8d0a72 100644 --- a/Documentation/arm64/booting.rst +++ b/Documentation/arm64/booting.rst @@ -369,6 +369,16 @@ Before jumping into the kernel, the following conditions must be met: - HCR_EL2.ATA (bit 56) must be initialised to 0b1. + For CPUs with the Scalable Matrix Extension version 2 (FEAT_SME2): + + - If EL3 is present: + + - SMCR_EL3.EZT0 (bit 30) must be initialised to 0b1. + + - If the kernel is entered at EL1 and EL2 is present: + + - SMCR_EL2.EZT0 (bit 30) must be initialised to 0b1. + The requirements described above for CPU mode, caches, MMUs, architected timers, coherency and system registers apply to all CPUs. All CPUs must enter the kernel in the same exception level. Where the values documented -- 2.7.4