[RFC PATCH 2/6] xen/arm: Add detection of Armv8.1-LSE atomic instructions

[Ash Wilding <ash.j.wilding@xxxxxxxxx>]

Use the new infrastructure for detecting CPU features in other ID
registers to detect the presence of Armv8.1-LSE atomic instructions,
as reported by ID_AA64ISAR0_EL1.Atomic.

While we're here, print detection of these instructions in setup.c's
processor_id().

Signed-off-by: Ash Wilding <ash.j.wilding@xxxxxxxxx>
---
 xen/arch/arm/setup.c             |  5 +++--
 xen/include/asm-arm/cpufeature.h | 10 +++++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 5121f06fc5..138e1957c5 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -128,10 +128,11 @@ static void __init processor_id(void)
            cpu_has_el2_32 ? "64+32" : cpu_has_el2_64 ? "64" : "No",
            cpu_has_el1_32 ? "64+32" : cpu_has_el1_64 ? "64" : "No",
            cpu_has_el0_32 ? "64+32" : cpu_has_el0_64 ? "64" : "No");
-    printk("    Extensions:%s%s%s\n",
+    printk("    Extensions:%s%s%s%s\n",
            cpu_has_fp ? " FloatingPoint" : "",
            cpu_has_simd ? " AdvancedSIMD" : "",
-           cpu_has_gicv3 ? " GICv3-SysReg" : "");
+           cpu_has_gicv3 ? " GICv3-SysReg" : "",
+           cpu_has_lse_atomics ? " LSE-Atomics" : "");
 
     /* Warn user if we find unknown floating-point features */
     if ( cpu_has_fp && (boot_cpu_feature(pfr64, fp) >= 2) )
diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index f9281ea343..2366926e82 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -15,6 +15,7 @@
 #define cpu_has_fp              (boot_cpu_feature(pfr64, fp) < 8)
 #define cpu_has_simd            (boot_cpu_feature(pfr64, simd) < 8)
 #define cpu_has_gicv3           (boot_cpu_feature(pfr64, gic) == 1)
+#define cpu_has_lse_atomics     (boot_cpu_feature(isa64, atomic) == 2)
 #endif
 
 #define cpu_has_arm       (boot_cpu_feature(pfr32, arm) == 1)
@@ -187,8 +188,15 @@ struct cpuinfo_arm {
         };
     } mm64;
 
-    struct {
+    union {
         uint64_t bits[2];
+        struct {
+            unsigned long __res0 : 20;
+            unsigned long atomic : 4;
+            unsigned long __res1 : 40;
+
+            unsigned long __res2 : 64;
+        };
     } isa64;
 
 #endif
-- 
2.24.3 (Apple Git-128)