util: Add cpuinfo for loongarch64

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiajie Chen <c@jia.je>
Message-Id: <20230916220151.526140-4-richard.henderson@linaro.org>

host/include/loongarch64/host/cpuinfo.h

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Host specific cpu identification for LoongArch
+ */
+
+#ifndef HOST_CPUINFO_H
+#define HOST_CPUINFO_H
+
+#define CPUINFO_ALWAYS          (1u << 0)  /* so cpuinfo is nonzero */
+#define CPUINFO_LSX             (1u << 1)
+
+/* Initialized with a constructor. */
+extern unsigned cpuinfo;
+
+/*
+ * We cannot rely on constructor ordering, so other constructors must
+ * use the function interface rather than the variable above.
+ */
+unsigned cpuinfo_init(void);
+
+#endif /* HOST_CPUINFO_H */

util/cpuinfo-loongarch.c

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Host specific cpu identification for LoongArch.
+ */
+
+#include "qemu/osdep.h"
+#include "host/cpuinfo.h"
+
+#ifdef CONFIG_GETAUXVAL
+# include <sys/auxv.h>
+#else
+# include "elf.h"
+#endif
+#include <asm/hwcap.h>
+
+unsigned cpuinfo;
+
+/* Called both as constructor and (possibly) via other constructors. */
+unsigned __attribute__((constructor)) cpuinfo_init(void)
+{
+    unsigned info = cpuinfo;
+    unsigned long hwcap;
+
+    if (info) {
+        return info;
+    }
+
+    hwcap = qemu_getauxval(AT_HWCAP);
+
+    info = CPUINFO_ALWAYS;
+    info |= (hwcap & HWCAP_LOONGARCH_LSX ? CPUINFO_LSX : 0);
+
+    cpuinfo = info;
+    return info;
+}

util/meson.build

@@ -113,6 +113,8 @@ if cpu == 'aarch64'
   util_ss.add(files('cpuinfo-aarch64.c'))
 elif cpu in ['x86', 'x86_64']
   util_ss.add(files('cpuinfo-i386.c'))
+elif cpu == 'loongarch64'
+  util_ss.add(files('cpuinfo-loongarch.c'))
 elif cpu in ['ppc', 'ppc64']
   util_ss.add(files('cpuinfo-ppc.c'))
 endif