From: Mark Brown Date: Wed, 12 May 2021 16:23:50 +0000 (+0100) Subject: arm64: Document requirement for access to FEAT_HCX X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ca940790d2ddc91e976f1e9e685052a54a1c50cf;p=linux.git arm64: Document requirement for access to FEAT_HCX v8.7 of the architecture introduced FEAT_HCX which adds an additional hypervisor configuration register HCRX_EL2. Even though Linux does not currently make use of this feature let's document that the EL3 trap for access to the register should be disabled so that we are able to make use of it in future. Signed-off-by: Mark Brown Acked-by: Catalin Marinas Link: https://lore.kernel.org/r/20210512162350.20349-1-broonie@kernel.org Signed-off-by: Will Deacon --- diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst index 18b8cc1bf32c6..a9192e7a231bf 100644 --- a/Documentation/arm64/booting.rst +++ b/Documentation/arm64/booting.rst @@ -277,6 +277,12 @@ Before jumping into the kernel, the following conditions must be met: - SCR_EL3.FGTEn (bit 27) must be initialised to 0b1. + For CPUs with support for HCRX_EL2 (FEAT_HCX) present: + + - If EL3 is present and the kernel is entered at EL2: + + - SCR_EL3.HXEn (bit 38) must be initialised to 0b1. + For CPUs with Advanced SIMD and floating point support: - If EL3 is present: