v4.19.13 snapshot.
diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c
new file mode 100644
index 0000000..cfa97ff
--- /dev/null
+++ b/arch/x86/kernel/cpu/rdrand.c
@@ -0,0 +1,59 @@
+/*
+ * This file is part of the Linux kernel.
+ *
+ * Copyright (c) 2011, Intel Corporation
+ * Authors: Fenghua Yu <fenghua.yu@intel.com>,
+ * H. Peter Anvin <hpa@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <asm/processor.h>
+#include <asm/archrandom.h>
+#include <asm/sections.h>
+
+static int __init x86_rdrand_setup(char *s)
+{
+ setup_clear_cpu_cap(X86_FEATURE_RDRAND);
+ setup_clear_cpu_cap(X86_FEATURE_RDSEED);
+ return 1;
+}
+__setup("nordrand", x86_rdrand_setup);
+
+/*
+ * RDRAND has Built-In-Self-Test (BIST) that runs on every invocation.
+ * Run the instruction a few times as a sanity check.
+ * If it fails, it is simple to disable RDRAND here.
+ */
+#define SANITY_CHECK_LOOPS 8
+
+#ifdef CONFIG_ARCH_RANDOM
+void x86_init_rdrand(struct cpuinfo_x86 *c)
+{
+ unsigned long tmp;
+ int i;
+
+ if (!cpu_has(c, X86_FEATURE_RDRAND))
+ return;
+
+ for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
+ if (!rdrand_long(&tmp)) {
+ clear_cpu_cap(c, X86_FEATURE_RDRAND);
+ pr_warn_once("rdrand: disabled\n");
+ return;
+ }
+ }
+}
+#endif