[PATCH 1/2] arm64: Add support for FEAT_HAFT

[Yicong Yang]

From: Yicong Yang <yangyicong at hisilicon.com>

Armv8.9/v9.4 introduces the feature Hardware managed Access Flag
for Table descriptors (FEAT_HAFT). The feature is indicated by
ID_AA64MMFR1_EL1.HAFDBS == 0b0011 and can be enabled by
TCR2_EL1.HAFT so it has a dependency on FEAT_TCR2.

This patch adds the Kconfig for FEAT_HAFT and support detecting
and enabling the feature.

Signed-off-by: Yicong Yang <yangyicong at hisilicon.com>
---
 arch/arm64/Kconfig                     | 20 ++++++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |  5 ++++
 arch/arm64/kernel/cpufeature.c         | 38 ++++++++++++++++++++++++++
 arch/arm64/tools/cpucaps               |  1 +
 arch/arm64/tools/sysreg                |  1 +
 5 files changed, 65 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b3fc891f1544..f263ae4139a5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2127,6 +2127,26 @@ config ARM64_EPAN
 	  if the cpu does not implement the feature.
 endmenu # "ARMv8.7 architectural features"
 
+menu "ARMv8.9 architectural features"
+
+config ARM64_HAFT
+	bool "Support for Hardware managed Access Flag for Table Descriptor"
+	depends on ARM64_HW_AFDBM
+	default y
+	help
+	  The ARMv8.9/ARMv9.5 introduces the feature Hardware managed Access
+	  Flag for Table descriptors. When enabled in TCR_EL1 (HAFT bit) on
+	  capable processors, an architectural executed memory access will
+	  update the Access Flag in each Table descriptor which is accessed
+	  during the translation table walk and for which the Access Flag is
+	  0. The Access Flag of the Table descriptor use the same bit of
+	  PTE_AF.
+
+	  The feature will only be enabled on supported CPUs. If unsure,
+	  say Y.
+
+endmenu # "ARMv8.9 architectural features"
+
 config ARM64_SVE
 	bool "ARM Scalable Vector Extension support"
 	default y
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 1f60aa1bc750..47bd29874e62 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -308,6 +308,11 @@
 #define TCR_TCMA1		(UL(1) << 58)
 #define TCR_DS			(UL(1) << 59)
 
+/*
+ * TCR2 Flags
+ */
+#define TCR2_HAFT		(UL(1) << 11)
+
 /*
  * TTBR.
  */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 646ecd3069fd..99402fd00f16 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2044,6 +2044,29 @@ static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
 
 #endif
 
+#if CONFIG_ARM64_HAFT
+
+static void cpu_enable_haft(struct arm64_cpu_capabilities const *cap)
+{
+	u64 reg = read_sysreg_s(SYS_TCR2_EL1);
+
+	reg |= TCR2_HAFT;
+	write_sysreg_s(reg, SYS_TCR2_EL1);
+	isb();
+	local_flush_tlb_all();
+}
+
+static bool has_haft(const struct arm64_cpu_capabilities *cap, int scope)
+{
+	/* FEAT_HAFT relies on FEAT_TCR2 */
+	if (!this_cpu_has_cap(ARM64_HAS_TCR2))
+		return false;
+
+	return has_cpuid_feature(cap, scope);
+}
+
+#endif
+
 #ifdef CONFIG_ARM64_AMU_EXTN
 
 /*
@@ -2580,6 +2603,21 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.cpus = &dbm_cpus,
 		ARM64_CPUID_FIELDS(ID_AA64MMFR1_EL1, HAFDBS, DBM)
 	},
+#endif
+#ifdef CONFIG_ARM64_HAFT
+	{
+		.desc = "Hardware managed Access Flag for Table Descriptor",
+		/*
+		 * Per Spec, software management of Access Flag for Table
+		 * descriptor is not supported, so make this feature system
+		 * wide.
+		 */
+		.type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
+		.capability = ARM64_HAFT,
+		.matches = has_haft,
+		.cpu_enable = cpu_enable_haft,
+		ARM64_CPUID_FIELDS(ID_AA64MMFR1_EL1, HAFDBS, HAFT)
+	},
 #endif
 	{
 		.desc = "CRC32 instructions",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index ac3429d892b9..0b7a3a237e5d 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -55,6 +55,7 @@ HAS_TLB_RANGE
 HAS_VA52
 HAS_VIRT_HOST_EXTN
 HAS_WFXT
+HAFT
 HW_DBM
 KVM_HVHE
 KVM_PROTECTED_MODE
diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
index 7ceaa1e0b4bc..9b3d15ea8a63 100644
--- a/arch/arm64/tools/sysreg
+++ b/arch/arm64/tools/sysreg
@@ -1688,6 +1688,7 @@ UnsignedEnum	3:0	HAFDBS
 	0b0000	NI
 	0b0001	AF
 	0b0010	DBM
+	0b0011	HAFT
 EndEnum
 EndSysreg
 
-- 
2.24.0