[PATCH v2 01/14] arm64/booting: Document boot requirements for FEAT_NMI

Mark Brown
2022-11-12T15:17:45Z

In order to use FEAT_NMI we must be able to use ALLINT, require that it
behave as though not trapped when it is present.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/arm64/booting.rst | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst
index 8aefa1001ae5..77d037bc7bf3 100644
--- a/Documentation/arm64/booting.rst
+++ b/Documentation/arm64/booting.rst
@@ -360,6 +360,12 @@ Before jumping into the kernel, the following conditions must be met:

- HCR_EL2.ATA (bit 56) must be initialised to 0b1.

+ For CPUs with Non-maskable Interrupts (FEAT_NMI):
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+ - HCRX_EL2.TALLINT must be initialised to 0b0.
+
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
--
2.30.2