[PATCH v13 06/32] arm64/fpsimd: Determine maximum virtualisable SME vector length

[Mark Brown]

As with SVE we can only virtualise SME vector lengths that are supported by
all CPUs in the system, implement similar checks to those for SVE. Since
unlike SVE there are no specific vector lengths that are architecturally
required the handling is subtly different, we report a system where this
happens with a maximum vector length of 0.

Signed-off-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/kernel/fpsimd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 314f5d61be11..7f2c44bd9fd5 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1281,6 +1281,7 @@ void __init sme_setup(void)
 	 * minimum available VL will be used.
 	 */
 	set_sme_default_vl(find_supported_vector_length(ARM64_VEC_SME, 32));
+	info->max_virtualisable_vl = vec_virtualisable_vl(info);
 
 	pr_info("SME: minimum available vector length %u bytes per vector\n",
 		info->min_vl);
@@ -1288,6 +1289,10 @@ void __init sme_setup(void)
 		info->max_vl);
 	pr_info("SME: default vector length %u bytes per vector\n",
 		get_sme_default_vl());
+
+	/* KVM decides whether to support mismatched systems. Just warn here: */
+	if (info->max_virtualisable_vl < info->max_vl)
+		pr_warn("SME: unvirtualisable vector lengths present\n");
 }
 
 #endif /* CONFIG_ARM64_SME */

-- 
2.47.3