[PATCH v3 01/22] arm64: cpufeature: Add cpucap for HPMN0

Colton Lewis
2025-06-26T20:05:53Z

Add a capability for FEAT_HPMN0, whether MDCR_EL2.HPMN can specify 0
counters reserved for the guest.

This required changing HPMN0 to an UnsignedEnum in tools/sysreg
because otherwise not all the appropriate macros are generated to add
it to arm64_cpu_capabilities_arm64_features.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
arch/arm64/kernel/cpufeature.c | 8 ++++++++
arch/arm64/tools/cpucaps | 1 +
arch/arm64/tools/sysreg | 6 +++---
3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index b34044e20128..73a7dac4b6f6 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -548,6 +548,7 @@ static const struct arm64_ftr_bits ftr_id_mmfr0[] = {
};

static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = {
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_EL1_HPMN0_SHIFT, 4, 0),
S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_EL1_DoubleLock_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR0_EL1_PMSVer_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_EL1_CTX_CMPs_SHIFT, 4, 0),
@@ -2896,6 +2897,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = has_cpuid_feature,
ARM64_CPUID_FIELDS(ID_AA64MMFR0_EL1, FGT, FGT2)
},
+ {
+ .desc = "FEAT_HPMN0",
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .capability = ARM64_HAS_HPMN0,
+ .matches = has_cpuid_feature,
+ ARM64_CPUID_FIELDS(ID_AA64DFR0_EL1, HPMN0, IMP)
+ },
#ifdef CONFIG_ARM64_SME
{
.desc = "Scalable Matrix Extension",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 10effd4cff6b..5b196ba21629 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -39,6 +39,7 @@ HAS_GIC_CPUIF_SYSREGS
HAS_GIC_PRIO_MASKING
HAS_GIC_PRIO_RELAXED_SYNC
HAS_HCR_NV1
+HAS_HPMN0
HAS_HCX
HAS_LDAPR
HAS_LPA2
diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
index 8a8cf6874298..d29742481754 100644
--- a/arch/arm64/tools/sysreg
+++ b/arch/arm64/tools/sysreg
@@ -1531,9 +1531,9 @@ EndEnum
EndSysreg

Sysreg ID_AA64DFR0_EL1 3 0 0 5 0
-Enum 63:60 HPMN0
- 0b0000 UNPREDICTABLE
- 0b0001 DEF
+UnsignedEnum 63:60 HPMN0
+ 0b0000 NI
+ 0b0001 IMP
EndEnum
UnsignedEnum 59:56 ExtTrcBuff
0b0000 NI
--
2.50.0.727.gbf7dc18ff4-goog