linux-kernel - [PATCH v1 5/5] arm64/config: add config to control whether enable HDBSS feature

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Message-ID: <20250311040321.1460-6-yezhenyu2@huawei.com>
Date: Tue, 11 Mar 2025 12:03:21 +0800
From: Zhenyu Ye <yezhenyu2@...wei.com>
To: <maz@...nel.org>, <yuzenghui@...wei.com>, <will@...nel.org>,
	<oliver.upton@...ux.dev>, <catalin.marinas@....com>, <joey.gouly@....com>
CC: <linux-kernel@...r.kernel.org>, <yezhenyu2@...wei.com>,
	<xiexiangyou@...wei.com>, <zhengchuan@...wei.com>, <wangzhou1@...ilicon.com>,
	<linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
	<kvmarm@...ts.linux.dev>
Subject: [PATCH v1 5/5] arm64/config: add config to control whether enable HDBSS feature

From: eillon <yezhenyu2@...wei.com>

The HDBSS feature introduces new assembly registers
(HDBSSBR_EL2 and HDBSSPROD_EL2), which depends on the armv9.5-a
compilation support. So add ARM64_HDBSS config to control whether
enable the HDBSS feature.

Signed-off-by: eillon <yezhenyu2@...wei.com>
---
 arch/arm64/Kconfig                  | 19 +++++++++++++++++++
 arch/arm64/Makefile                 |  4 +++-
 arch/arm64/include/asm/cpufeature.h |  3 +++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 940343beb3d4..3458261eb14b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2237,6 +2237,25 @@ config ARM64_GCS
 
 endmenu # "v9.4 architectural features"
 
+menu "ARMv9.5 architectural features"
+
+config ARM64_HDBSS
+	bool "Enable support for Hardware Dirty state tracking Structure (HDBSS)"
+	default y
+	depends on AS_HAS_ARMV9_5
+	help
+	  Hardware Dirty state tracking Structure(HDBSS) enhances tracking
+	  translation table descriptors’ dirty state to reduce the cost of
+	  surveying for dirtied granules.
+
+	  The feature introduces new assembly registers (HDBSSBR_EL2 and
+	  HDBSSPROD_EL2), which depends on AS_HAS_ARMV9_5.
+
+config AS_HAS_ARMV9_5
+	def_bool $(cc-option,-Wa$(comma)-march=armv9.5-a)
+
+endmenu # "ARMv9.5 architectural features"
+
 config ARM64_SVE
 	bool "ARM Scalable Vector Extension support"
 	default y
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 2b25d671365f..f22507fb09b9 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -103,7 +103,9 @@ endif
 # freely generate instructions which are not supported by earlier architecture
 # versions, which would prevent a single kernel image from working on earlier
 # hardware.
-ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
+ifeq ($(CONFIG_AS_HAS_ARMV9_5), y)
+  asm-arch := armv9.5-a
+else ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
   asm-arch := armv8.5-a
 else ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
   asm-arch := armv8.4-a
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index c76d51506562..32e432827934 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -748,6 +748,9 @@ static inline bool system_supports_hdbss(void)
 	u64 mmfr1;
 	u32 val;
 
+	if (!IS_ENABLED(CONFIG_ARM64_HDBSS))
+		return false;
+
 	mmfr1 =	read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
 	val = cpuid_feature_extract_unsigned_field(mmfr1,
 						ID_AA64MMFR1_EL1_HAFDBS_SHIFT);
-- 
2.39.3