arm64/sve: Ensure that all fields in ZCR_EL1 are set to known values

At present nothing in our CPU initialisation code ever sets unknown fields
in ZCR_EL1 to known values, all updates to ZCR_EL1 are read/modify/write
sequences for LEN. All the unknown fields are RES0, explicitly initialise
them as such to avoid future surprises.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240213-arm64-fp-init-vec-cr-v1-1-7e7c2d584f26@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index a5dc6f764195847251dc25c196304cbef44d8850..cc3c9ad877a8c0be09a42ef44ef7fec69628f726 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1134,6 +1134,8 @@ void cpu_enable_sve(const struct arm64_cpu_capabilities *__always_unused p)
 {
        write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1);
        isb();
+
+       write_sysreg_s(0, SYS_ZCR_EL1);
 }
 
 void __init sve_setup(void)