cpu: add ppc64le POWER10 detection

Change-ID: Iffd467d0600a6dcec51232d5ca65ea7c4e7cac77
Assisted-By: "claude my eyes right out"
Reviewed-on: https://go-review.googlesource.com/c/sys/+/822324
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Samuel Karp <samuelkarp@google.com>

cpu/cpu.go

diff --git a/cpu/cpu.go b/cpu/cpu.go
index 679edb5..df8dbd1 100644
--- a/cpu/cpu.go
+++ b/cpu/cpu.go
@@ -182,12 +182,13 @@
 // require kernel support to work (DARN, SCV), so there are feature bits for
 // those as well. The struct is padded to avoid false sharing.
 var PPC64 struct {
-	_        CacheLinePad
-	HasDARN  bool // Hardware random number generator (requires kernel enablement)
-	HasSCV   bool // Syscall vectored (requires kernel enablement)
-	IsPOWER8 bool // ISA v2.07 (POWER8)
-	IsPOWER9 bool // ISA v3.00 (POWER9), implies IsPOWER8
-	_        CacheLinePad
+	_         CacheLinePad
+	HasDARN   bool // Hardware random number generator (requires kernel enablement)
+	HasSCV    bool // Syscall vectored (requires kernel enablement)
+	IsPOWER8  bool // ISA v2.07 (POWER8)
+	IsPOWER9  bool // ISA v3.00 (POWER9), implies IsPOWER8
+	IsPOWER10 bool // ISA v3.1 (POWER10 and POWER11; POWER11 did not add a new architected level), implies IsPOWER9
+	_         CacheLinePad
 }
 
 // S390X contains the supported CPU features of the current IBM Z

cpu/cpu_linux_ppc64x.go

diff --git a/cpu/cpu_linux_ppc64x.go b/cpu/cpu_linux_ppc64x.go
index 197188e..70b3dc7 100644
--- a/cpu/cpu_linux_ppc64x.go
+++ b/cpu/cpu_linux_ppc64x.go
@@ -11,6 +11,7 @@
 	// ISA Level
 	_PPC_FEATURE2_ARCH_2_07 = 0x80000000
 	_PPC_FEATURE2_ARCH_3_00 = 0x00800000
+	_PPC_FEATURE2_ARCH_3_1  = 0x00040000
 
 	// CPU features
 	_PPC_FEATURE2_DARN = 0x00200000
@@ -21,6 +22,9 @@
 	// HWCAP2 feature bits
 	PPC64.IsPOWER8 = isSet(hwCap2, _PPC_FEATURE2_ARCH_2_07)
 	PPC64.IsPOWER9 = isSet(hwCap2, _PPC_FEATURE2_ARCH_3_00)
+	// ISA 3.1 covers both POWER10 and POWER11: POWER11 did not introduce a
+	// new architected HWCAP level, so there is no separate IsPOWER11.
+	PPC64.IsPOWER10 = isSet(hwCap2, _PPC_FEATURE2_ARCH_3_1)
 	PPC64.HasDARN = isSet(hwCap2, _PPC_FEATURE2_DARN)
 	PPC64.HasSCV = isSet(hwCap2, _PPC_FEATURE2_SCV)
 }