arm64/sme: Add basic enumeration for SME2

Add basic feature detection for SME2, detecting that the feature is present
and disabling traps for ZT0.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-8-f2fa0aef982f@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 9e168a9eb615..717ae4aaa021 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1302,6 +1302,17 @@ void sme_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
  * This must be called after sme_kernel_enable(), we rely on the
  * feature table being sorted to ensure this.
  */
+void sme2_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
+{
+	/* Allow use of ZT0 */
+	write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_EZT0_MASK,
+		       SYS_SMCR_EL1);
+}
+
+/*
+ * This must be called after sme_kernel_enable(), we rely on the
+ * feature table being sorted to ensure this.
+ */
 void fa64_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p)
 {
 	/* Allow use of FA64 */