[PATCH v5 06/15] KVM: arm64: Add support for FEAT_HDBSS

[Tian Zheng]

Armv9.5 introduces the Hardware dirty state tracking structure
(HDBSS), indicated by ID_AA64MMFR1_EL1.HAFDBS == 0b0100.

Add CPU capability detection for HDBSS. The capability is restricted
to VHE systems, as the buffer registers HDBSSBR_EL2 and HDBSSPROD_EL2
are EL2-only and are programmed directly from host context. A
system_supports_hdbss() helper is provided for the rest of the series.

Suggested-by: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
Co-developed-by: Eillon <yezhenyu2@xxxxxxxxxx>
Signed-off-by: Eillon <yezhenyu2@xxxxxxxxxx>
Signed-off-by: Tian Zheng <zhengtian10@xxxxxxxxxx>
---
 arch/arm64/include/asm/cpufeature.h |  5 +++++
 arch/arm64/kernel/cpufeature.c      | 12 ++++++++++++
 arch/arm64/tools/cpucaps            |  1 +
 3 files changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 4f04ad82ea34..0592e6f6b4d7 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -856,6 +856,11 @@ static inline bool system_supports_haft(void)
 	return cpus_have_final_cap(ARM64_HAFT);
 }

+static inline bool system_supports_hdbss(void)
+{
+	return cpus_have_final_cap(ARM64_HAS_HDBSS);
+}
+
 static __always_inline bool system_supports_mpam(void)
 {
 	return alternative_has_cap_unlikely(ARM64_MPAM);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 32102c3912fa..12fa37328dd2 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2158,6 +2158,11 @@ static bool hvhe_possible(const struct arm64_cpu_capabilities *entry,
 	return arm64_test_sw_feature_override(ARM64_SW_FEATURE_OVERRIDE_HVHE);
 }

+static bool has_vhe_hdbss(const struct arm64_cpu_capabilities *entry, int scope)
+{
+	return is_kernel_in_hyp_mode() && has_cpuid_feature(entry, scope);
+}
+
 bool cpu_supports_bbml3(void)
 {
 	/* CPUs that support BBML3 but dont advertise through ID_AA64MMFR2_EL1 */
@@ -2816,6 +2821,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		ARM64_CPUID_FIELDS(ID_AA64MMFR1_EL1, HAFDBS, HAFT)
 	},
 #endif
+	{
+		.desc = "Hardware dirty state tracking structure (HDBSS)",
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.capability = ARM64_HAS_HDBSS,
+		.matches = has_vhe_hdbss,
+		ARM64_CPUID_FIELDS(ID_AA64MMFR1_EL1, HAFDBS, HDBSS)
+	},
 	{
 		.desc = "CRC32 instructions",
 		.capability = ARM64_HAS_CRC32,
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 2775ba3359cf..8acb3db980c9 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -71,6 +71,7 @@ HAS_VA52
 HAS_VIRT_HOST_EXTN
 HAS_WFXT
 HAS_XNX
+HAS_HDBSS
 HAFT
 HW_DBM
 KVM_HVHE
--
2.43.0