Mark Rutland mark.rutland@arm.com writes:
On Thu, Jun 26, 2025 at 08:04:37PM +0000, Colton Lewis wrote:
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.
I agree it's appropriate to mark ID_AA64DFR0_EL1.HPMN0 as an UnsignedEnum. It follows the usual ID scheme per ARM DDI 0487 L.a section D24.1.3, and zero means not present, so it must be unsigned.
Likewise, the value renames (UNPREDICTABLE => NI and DEF => IMP) look fine to me.
Signed-off-by: Colton Lewis coltonlewis@google.com
I have one minor nit below, but either way:
Acked-by: Mark Rutland mark.rutland@arm.com
Thank you Mark
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",
Minor nit, but we can drop the "FEAT_" prefix here, for consistency with other features (e.g. E0PD, FPMR).
Mark.
Will do.
.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