[PATCH 06/22] arm64: mte: CPU feature detection and initial sysreg configuration

From: Catalin Marinas <catalin.marinas@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org,
	Richard Earnshaw <Richard.Earnshaw@arm.com>,
	Szabolcs Nagy <szabolcs.nagy@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	linux-mm@kvack.org, Andrey Konovalov <andreyknvl@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>
Subject: [PATCH 06/22] arm64: mte: CPU feature detection and initial sysreg configuration
Date: Wed, 11 Dec 2019 18:40:11 +0000	[thread overview]
Message-ID: <20191211184027.20130-7-catalin.marinas@arm.com> (raw)
In-Reply-To: <20191211184027.20130-1-catalin.marinas@arm.com>

From: Vincenzo Frascino <vincenzo.frascino@arm.com>

Add the cpufeature and hwcap entries to detect the presence of MTE on
the boot CPUs (primary and secondary). Any late secondary CPU not
supporting the feature, if detected during boot, will be parked.

In addition, add the minimum SCTLR_EL1 and HCR_EL2 bits for enabling
MTE. Without subsequent setting of MAIR, these bits do not have an
effect on tag checking.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/cpucaps.h    |  5 ++++-
 arch/arm64/include/asm/cpufeature.h |  6 ++++++
 arch/arm64/include/asm/hwcap.h      |  1 +
 arch/arm64/include/asm/kvm_arm.h    |  2 +-
 arch/arm64/include/asm/sysreg.h     |  1 +
 arch/arm64/include/uapi/asm/hwcap.h |  2 ++
 arch/arm64/kernel/cpufeature.c      | 29 +++++++++++++++++++++++++++++
 arch/arm64/kernel/cpuinfo.c         |  2 ++
 8 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index b92683871119..8a56604ec04e 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -56,7 +56,10 @@
 #define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
 #define ARM64_WORKAROUND_1542419		47
 #define ARM64_WORKAROUND_1319367		48
+/* 49 reserved for ARM64_HAS_E0PD */
+/* 50 reserved for ARM64_BTI */
+#define ARM64_MTE				51
 
-#define ARM64_NCAPS				49
+#define ARM64_NCAPS				52
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 4261d55e8506..7d464797eff6 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -607,6 +607,12 @@ static inline bool system_uses_irq_prio_masking(void)
 	       cpus_have_const_cap(ARM64_HAS_IRQ_PRIO_MASKING);
 }
 
+static inline bool system_supports_mte(void)
+{
+	return IS_ENABLED(CONFIG_ARM64_MTE) &&
+		cpus_have_const_cap(ARM64_MTE);
+}
+
 static inline bool system_has_prio_mask_debugging(void)
 {
 	return IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) &&
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 3d2f2472a36c..a98b3347c4a4 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -86,6 +86,7 @@
 #define KERNEL_HWCAP_SVESM4		__khwcap2_feature(SVESM4)
 #define KERNEL_HWCAP_FLAGM2		__khwcap2_feature(FLAGM2)
 #define KERNEL_HWCAP_FRINT		__khwcap2_feature(FRINT)
+#define KERNEL_HWCAP_MTE		__khwcap2_feature(MTE)
 
 /*
  * This yields a mask that user programs can use to figure out what
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 0b25f9a81c57..37bcb93b376c 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -78,7 +78,7 @@
 			 HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
 			 HCR_FMO | HCR_IMO)
 #define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
-#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK)
+#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK | HCR_ATA)
 #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
 
 /* TCR_EL2 Registers bits */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 609d1b3238dd..9e5753272f4b 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -558,6 +558,7 @@
 			 SCTLR_EL1_SA0  | SCTLR_EL1_SED  | SCTLR_ELx_I    |\
 			 SCTLR_EL1_DZE  | SCTLR_EL1_UCT                   |\
 			 SCTLR_EL1_NTWE | SCTLR_ELx_IESB | SCTLR_EL1_SPAN |\
+			 SCTLR_ELx_ITFSB| SCTLR_ELx_ATA  | SCTLR_EL1_ATA0 |\
 			 ENDIAN_SET_EL1 | SCTLR_EL1_UCI  | SCTLR_EL1_RES1)
 
 /* MAIR_ELx memory attributes (used by Linux) */
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index a1e72886b30c..57a29c9b29d9 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -65,5 +65,7 @@
 #define HWCAP2_SVESM4		(1 << 6)
 #define HWCAP2_FLAGM2		(1 << 7)
 #define HWCAP2_FRINT		(1 << 8)
+/* bit 9 reserved for HWCAP2_BTI */
+#define HWCAP2_MTE		(1 << 10)
 
 #endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 04cf64e9f0c9..a3eea2cce6b0 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -172,6 +172,8 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
 
 static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI),
+	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_MTE),
+		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_MTE_SHIFT, 4, ID_AA64PFR1_MTE_NI),
 	ARM64_FTR_END,
 };
 
@@ -1267,6 +1269,17 @@ static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
 }
 #endif
 
+#ifdef CONFIG_ARM64_MTE
+static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
+{
+	write_sysreg_s(SYS_GCR_EL1_RRND, SYS_GCR_EL1);
+	write_sysreg_s(0, SYS_TFSR_EL1);
+	write_sysreg_s(0, SYS_TFSRE0_EL1);
+
+	isb();
+}
+#endif /* CONFIG_ARM64_MTE */
+
 static const struct arm64_cpu_capabilities arm64_features[] = {
 	{
 		.desc = "GIC system register CPU interface",
@@ -1567,6 +1580,19 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.min_field_value = 1,
 	},
 #endif
+#ifdef CONFIG_ARM64_MTE
+	{
+		.desc = "Memory Tagging Extension",
+		.capability = ARM64_MTE,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64PFR1_EL1,
+		.field_pos = ID_AA64PFR1_MTE_SHIFT,
+		.min_field_value = ID_AA64PFR1_MTE,
+		.sign = FTR_UNSIGNED,
+		.cpu_enable = cpu_enable_mte,
+	},
+#endif /* CONFIG_ARM64_MTE */
 	{},
 };
 
@@ -1666,6 +1692,9 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
 	HWCAP_MULTI_CAP(ptr_auth_hwcap_addr_matches, CAP_HWCAP, KERNEL_HWCAP_PACA),
 	HWCAP_MULTI_CAP(ptr_auth_hwcap_gen_matches, CAP_HWCAP, KERNEL_HWCAP_PACG),
 #endif
+#ifdef CONFIG_ARM64_MTE
+	HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_MTE_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_MTE, CAP_HWCAP, KERNEL_HWCAP_MTE),
+#endif /* CONFIG_ARM64_MTE */
 	{},
 };
 
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 56bba746da1c..6f686e64610e 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -84,6 +84,8 @@ static const char *const hwcap_str[] = {
 	"svesm4",
 	"flagm2",
 	"frint",
+	"",		/* reserved for BTI */
+	"mte",
 	NULL
 };
