[PATCH 2/3] host/x86_64: Implement atomic64_set with MOVDIR64B

Detect the host feature in cpuid, then use it.

Signed-off-by: Richard Henderson <[email protected]>
---
 host/include/x86_64/host/cpuinfo.h            |  1 +
 include/qemu/cpuid.h                          |  3 +++
 util/cpuinfo-i386.c                           |  1 +
 host/include/x86_64/host/atomic512-ldst.h.inc | 21 +++++++++++++++++++
 4 files changed, 26 insertions(+)
 create mode 100644 host/include/x86_64/host/atomic512-ldst.h.inc

diff --git a/host/include/x86_64/host/cpuinfo.h b/host/include/x86_64/host/cpuinfo.h
index 93d029d499..34c4334f3d 100644
--- a/host/include/x86_64/host/cpuinfo.h
+++ b/host/include/x86_64/host/cpuinfo.h
@@ -28,6 +28,7 @@
 #define CPUINFO_AES             (1u << 18)
 #define CPUINFO_PCLMUL          (1u << 19)
 #define CPUINFO_GFNI            (1u << 20)
+#define CPUINFO_MOVDIR64B       (1u << 21)
 
 /* Initialized with a constructor. */
 extern unsigned cpuinfo;
diff --git a/include/qemu/cpuid.h b/include/qemu/cpuid.h
index de7a900509..435fc7af9c 100644
--- a/include/qemu/cpuid.h
+++ b/include/qemu/cpuid.h
@@ -71,6 +71,9 @@
 #ifndef bit_GFNI
 #define bit_GFNI        (1 << 8)
 #endif
+#ifndef bit_MOVDIR64B
+#define bit_MOVDIR64B   (1 << 28)
+#endif
 
 /* Leaf 0x80000001, %ecx */
 #ifndef bit_LZCNT
diff --git a/util/cpuinfo-i386.c b/util/cpuinfo-i386.c
index f4c5b6ff40..bb88abcf8f 100644
--- a/util/cpuinfo-i386.c
+++ b/util/cpuinfo-i386.c
@@ -29,6 +29,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
         __cpuid_count(7, 0, a, b7, c7, d);
         info |= (b7 & bit_BMI ? CPUINFO_BMI1 : 0);
         info |= (b7 & bit_BMI2 ? CPUINFO_BMI2 : 0);
+        info |= (c7 & bit_MOVDIR64B ? CPUINFO_MOVDIR64B : 0);
     }
 
     if (max >= 1) {
diff --git a/host/include/x86_64/host/atomic512-ldst.h.inc b/host/include/x86_64/host/atomic512-ldst.h.inc
new file mode 100644
index 0000000000..7db9a0b753
--- /dev/null
+++ b/host/include/x86_64/host/atomic512-ldst.h.inc
@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Load/store for 512-bit atomic operations, generic version.
+ */
+
+#ifndef HOST_ATOMIC512_LDST_H
+#define HOST_ATOMIC512_LDST_H
+
+#include "host/cpuinfo.h"
+
+#define HAVE_ATOMIC512_LD 0
+#define HAVE_ATOMIC512_ST likely(cpuinfo & CPUINFO_MOVDIR64B)
+
+Value64 QEMU_ERROR("unsupported atomic") atomic64_read(const void *s);
+
+static inline void atomic64_set(void *d, const Value64 *v)
+{
+    asm volatile("movdir64b (%1),%0" : : "r"(d), "r"(v) : "memory");
+}
+
+#endif /* HOST_ATOMIC512_LDST_H */
-- 
2.43.0