arm64: cpufeature: Expose ID_AA64ISAR2_EL1.ATS1A to KVM

KVM needs to know if the HW implements FEAT_ATS1A in order to correctly
sanitise HFGITR_EL2.ATS1E1A, which otherwise defaults to RES0 and
AT S1E1A traps are handled as UNDEF.

Solves this by exposing ID_AA64ISAR2_EL1.ATS1A to the rest of the kernel.

Fixes: ff987ffc0c18c ("KVM: arm64: nv: Add support for FEAT_ATS1A")
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Link: https://patch.msgid.link/20260602155430.2088142-4-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 6d53bb15cf7bb48e926330c7ff0c93c0c14b14c2..62b0d77217eebe672acdf8220e064245bf979ab4 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -266,6 +266,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
 };
 
 static const struct arm64_ftr_bits ftr_id_aa64isar2[] = {
+       ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_EL1_ATS1A_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_EL1_LUT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_EL1_CSSC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_EL1_RPRFM_SHIFT, 4, 0),