host/include/aarch64: Implement clmul.h

Detect PMULL in cpuinfo; implement the accel hook.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

host/include/aarch64/host/cpuinfo.h

@@ -10,6 +10,7 @@
 #define CPUINFO_LSE             (1u << 1)
 #define CPUINFO_LSE2            (1u << 2)
 #define CPUINFO_AES             (1u << 3)
+#define CPUINFO_PMULL           (1u << 4)
 
 /* Initialized with a constructor. */
 extern unsigned cpuinfo;

host/include/aarch64/host/crypto/clmul.h

@@ -0,0 +1,41 @@
+/*
+ * AArch64 specific clmul acceleration.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef AARCH64_HOST_CRYPTO_CLMUL_H
+#define AARCH64_HOST_CRYPTO_CLMUL_H
+
+#include "host/cpuinfo.h"
+#include <arm_neon.h>
+
+/*
+ * 64x64->128 pmull is available with FEAT_PMULL.
+ * Both FEAT_AES and FEAT_PMULL are covered under the same macro.
+ */
+#ifdef __ARM_FEATURE_AES
+# define HAVE_CLMUL_ACCEL  true
+#else
+# define HAVE_CLMUL_ACCEL  likely(cpuinfo & CPUINFO_PMULL)
+#endif
+#if !defined(__ARM_FEATURE_AES) && defined(CONFIG_ARM_AES_BUILTIN)
+# define ATTR_CLMUL_ACCEL  __attribute__((target("+crypto")))
+#else
+# define ATTR_CLMUL_ACCEL
+#endif
+
+static inline Int128 ATTR_CLMUL_ACCEL
+clmul_64_accel(uint64_t n, uint64_t m)
+{
+    union { poly128_t v; Int128 s; } u;
+
+#ifdef CONFIG_ARM_AES_BUILTIN
+    u.v = vmull_p64((poly64_t)n, (poly64_t)m);
+#else
+    asm(".arch_extension aes\n\t"
+        "pmull %0.1q, %1.1d, %2.1d" : "=w"(u.v) : "w"(n), "w"(m));
+#endif
+    return u.s;
+}
+
+#endif /* AARCH64_HOST_CRYPTO_CLMUL_H */

util/cpuinfo-aarch64.c

@@ -56,12 +56,14 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
     unsigned long hwcap = qemu_getauxval(AT_HWCAP);
     info |= (hwcap & HWCAP_ATOMICS ? CPUINFO_LSE : 0);
     info |= (hwcap & HWCAP_USCAT ? CPUINFO_LSE2 : 0);
-    info |= (hwcap & HWCAP_AES ? CPUINFO_AES: 0);
+    info |= (hwcap & HWCAP_AES ? CPUINFO_AES : 0);
+    info |= (hwcap & HWCAP_PMULL ? CPUINFO_PMULL : 0);
 #endif
 #ifdef CONFIG_DARWIN
     info |= sysctl_for_bool("hw.optional.arm.FEAT_LSE") * CPUINFO_LSE;
     info |= sysctl_for_bool("hw.optional.arm.FEAT_LSE2") * CPUINFO_LSE2;
     info |= sysctl_for_bool("hw.optional.arm.FEAT_AES") * CPUINFO_AES;
+    info |= sysctl_for_bool("hw.optional.arm.FEAT_PMULL") * CPUINFO_PMULL;
 #endif
 
     cpuinfo = info;