[PATCH v5 11/30] arm64: enable the Permission Overlay Extension for EL0

[Joey Gouly]

Expose a HWCAP and ID_AA64MMFR3_EL1_S1POE to userspace, so they can be used to
check if the CPU supports the feature.

Signed-off-by: Joey Gouly <joey.go...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <w...@kernel.org>
Reviewed-by: Catalin Marinas <catalin.mari...@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khand...@arm.com>
---
 Documentation/arch/arm64/elf_hwcaps.rst |  2 ++
 arch/arm64/include/asm/hwcap.h          |  1 +
 arch/arm64/include/uapi/asm/hwcap.h     |  1 +
 arch/arm64/kernel/cpufeature.c          | 14 ++++++++++++++
 arch/arm64/kernel/cpuinfo.c             |  1 +
 5 files changed, 19 insertions(+)

diff --git Documentation/arch/arm64/elf_hwcaps.rst 
Documentation/arch/arm64/elf_hwcaps.rst
index 448c1664879b..694f67fa07d1 100644
--- Documentation/arch/arm64/elf_hwcaps.rst
+++ Documentation/arch/arm64/elf_hwcaps.rst
@@ -365,6 +365,8 @@ HWCAP2_SME_SF8DP2
 HWCAP2_SME_SF8DP4
     Functionality implied by ID_AA64SMFR0_EL1.SF8DP4 == 0b1.
 
+HWCAP2_POE
+    Functionality implied by ID_AA64MMFR3_EL1.S1POE == 0b0001.
 
 4. Unused AT_HWCAP bits
 -----------------------
diff --git arch/arm64/include/asm/hwcap.h arch/arm64/include/asm/hwcap.h
index 4edd3b61df11..a775adddecf2 100644
--- arch/arm64/include/asm/hwcap.h
+++ arch/arm64/include/asm/hwcap.h
@@ -157,6 +157,7 @@
 #define KERNEL_HWCAP_SME_SF8FMA                __khwcap2_feature(SME_SF8FMA)
 #define KERNEL_HWCAP_SME_SF8DP4                __khwcap2_feature(SME_SF8DP4)
 #define KERNEL_HWCAP_SME_SF8DP2                __khwcap2_feature(SME_SF8DP2)
+#define KERNEL_HWCAP_POE               __khwcap2_feature(POE)
 
 /*
  * This yields a mask that user programs can use to figure out what
diff --git arch/arm64/include/uapi/asm/hwcap.h 
arch/arm64/include/uapi/asm/hwcap.h
index 285610e626f5..055381b2c615 100644
--- arch/arm64/include/uapi/asm/hwcap.h
+++ arch/arm64/include/uapi/asm/hwcap.h
@@ -122,5 +122,6 @@
 #define HWCAP2_SME_SF8FMA      (1UL << 60)
 #define HWCAP2_SME_SF8DP4      (1UL << 61)
 #define HWCAP2_SME_SF8DP2      (1UL << 62)
+#define HWCAP2_POE             (1UL << 63)
 
 #endif /* _UAPI__ASM_HWCAP_H */
diff --git arch/arm64/kernel/cpufeature.c arch/arm64/kernel/cpufeature.c
index 2daf5597cd65..718728a85430 100644
--- arch/arm64/kernel/cpufeature.c
+++ arch/arm64/kernel/cpufeature.c
@@ -466,6 +466,8 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
 };
 
 static const struct arm64_ftr_bits ftr_id_aa64mmfr3[] = {
+       ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_POE),
+                      FTR_NONSTRICT, FTR_LOWER_SAFE, 
ID_AA64MMFR3_EL1_S1POE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, 
ID_AA64MMFR3_EL1_S1PIE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, 
ID_AA64MMFR3_EL1_TCRX_SHIFT, 4, 0),
        ARM64_FTR_END,
@@ -2348,6 +2350,14 @@ static void cpu_enable_mops(const struct 
arm64_cpu_capabilities *__unused)
        sysreg_clear_set(sctlr_el1, 0, SCTLR_EL1_MSCEn);
 }
 
+#ifdef CONFIG_ARM64_POE
+static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused)
+{
+       sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1x_E0POE);
+       sysreg_clear_set(CPACR_EL1, 0, CPACR_ELx_E0POE);
+}
+#endif
+
 /* Internal helper functions to match cpu capability type */
 static bool
 cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap)
@@ -2876,6 +2886,7 @@ static const struct arm64_cpu_capabilities 
arm64_features[] = {
                .capability = ARM64_HAS_S1POE,
                .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
                .matches = has_cpuid_feature,
+               .cpu_enable = cpu_enable_poe,
                ARM64_CPUID_FIELDS(ID_AA64MMFR3_EL1, S1POE, IMP)
        },
 #endif
@@ -3043,6 +3054,9 @@ static const struct arm64_cpu_capabilities 
arm64_elf_hwcaps[] = {
        HWCAP_CAP(ID_AA64FPFR0_EL1, F8DP2, IMP, CAP_HWCAP, KERNEL_HWCAP_F8DP2),
        HWCAP_CAP(ID_AA64FPFR0_EL1, F8E4M3, IMP, CAP_HWCAP, 
KERNEL_HWCAP_F8E4M3),
        HWCAP_CAP(ID_AA64FPFR0_EL1, F8E5M2, IMP, CAP_HWCAP, 
KERNEL_HWCAP_F8E5M2),
+#ifdef CONFIG_ARM64_POE
+       HWCAP_CAP(ID_AA64MMFR3_EL1, S1POE, IMP, CAP_HWCAP, KERNEL_HWCAP_POE),
+#endif
        {},
 };
 
diff --git arch/arm64/kernel/cpuinfo.c arch/arm64/kernel/cpuinfo.c
index 09eeaa24d456..b9db812082b3 100644
--- arch/arm64/kernel/cpuinfo.c
+++ arch/arm64/kernel/cpuinfo.c
@@ -143,6 +143,7 @@ static const char *const hwcap_str[] = {
        [KERNEL_HWCAP_SME_SF8FMA]       = "smesf8fma",
        [KERNEL_HWCAP_SME_SF8DP4]       = "smesf8dp4",
        [KERNEL_HWCAP_SME_SF8DP2]       = "smesf8dp2",
+       [KERNEL_HWCAP_POE]              = "poe",
 };
 
 #ifdef CONFIG_COMPAT
-- 
2.25.1