[PATCH v13 1/8] arm64: cpufeature: add FEAT_LSUI

[Yeoreum Yun <yeoreum.yun@arm.com>]

Since Armv9.6, FEAT_LSUI introduces load/store instructions that allow
privileged code to access user memory without clearing the PSTATE.PAN bit.

Add CPU feature detection for FEAT_LSUI and enable its use
when FEAT_PAN is present so that removes the need for SW_PAN handling
when using LSUI instructions.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 arch/arm64/kernel/cpufeature.c | 10 ++++++++++
 arch/arm64/tools/cpucaps       |  1 +
 2 files changed, 11 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c31f8e17732a..5074ff32176f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -281,6 +281,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar2[] = {
 
 static const struct arm64_ftr_bits ftr_id_aa64isar3[] = {
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR3_EL1_FPRCVT_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR3_EL1_LSUI_SHIFT, 4, ID_AA64ISAR3_EL1_LSUI_NI),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR3_EL1_LSFE_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR3_EL1_FAMINMAX_SHIFT, 4, 0),
 	ARM64_FTR_END,
@@ -3169,6 +3170,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.cpu_enable = cpu_enable_ls64_v,
 		ARM64_CPUID_FIELDS(ID_AA64ISAR1_EL1, LS64, LS64_V)
 	},
+#ifdef CONFIG_ARM64_LSUI
+	{
+		.desc = "Unprivileged Load Store Instructions (LSUI)",
+		.capability = ARM64_HAS_LSUI,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		ARM64_CPUID_FIELDS(ID_AA64ISAR3_EL1, LSUI, IMP)
+	},
+#endif
 	{},
 };
 
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 7261553b644b..b7286d977788 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -48,6 +48,7 @@ HAS_LPA2
 HAS_LSE_ATOMICS
 HAS_LS64
 HAS_LS64_V
+HAS_LSUI
 HAS_MOPS
 HAS_NESTED_VIRT
 HAS_BBML2_NOABORT
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}