Hyper-V hosts make 64 bytes of entropy available to guests in the form

of a OEM0 ACPI table.  acpihve(4) feeds this data into the kernel
entropy pool.

This is less interesting for machines with rdrand, but there are still
pre ivy bridge machines running Hyper-V (including parts of Azure).

ok mikeb@ reyk@ deraadt@ mlarkin@

3 files changed, 43 insertions, 4 deletions

diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
index 2e63b525835..a4471deb91c 100644
--- a/share/man/man4/Makefile
+++ b/share/man/man4/Makefile
@@ -1,8 +1,8 @@
-#	$OpenBSD: Makefile,v 1.648 2017/01/03 20:35:46 kettenis Exp $
+#	$OpenBSD: Makefile,v 1.649 2017/01/10 08:54:14 jsg Exp $
 
 MAN=	aac.4 ac97.4 acphy.4 \
 	acpi.4 acpiac.4 acpials.4 acpiasus.4 acpibat.4 \
-	acpibtn.4 acpicbkbd.4 acpicpu.4 acpidock.4 \
+	acpibtn.4 acpicbkbd.4 acpicpu.4 acpidock.4 acpihve.4 \
 	acpiec.4 acpihpet.4 acpimadt.4 acpimcfg.4 acpiprt.4 acpipwrres.4 \
 	acpisony.4 acpithinkpad.4 acpitoshiba.4 acpitimer.4 acpivideo.4 \
 	acpivout.4 acpitz.4 \
diff --git a/share/man/man4/acpi.4 b/share/man/man4/acpi.4
index 231de3385e9..b51b64f0875 100644
--- a/share/man/man4/acpi.4
+++ b/share/man/man4/acpi.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: acpi.4,v 1.51 2016/08/23 18:58:53 jcs Exp $
+.\"	$OpenBSD: acpi.4,v 1.52 2017/01/10 08:54:14 jsg Exp $
 .\"
 .\" Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: August 23 2016 $
+.Dd $Mdocdate: January 10 2017 $
 .Dt ACPI 4
 .Os
 .Sh NAME
@@ -58,6 +58,8 @@ ACPI docking station
 ACPI embedded controller
 .It Xr acpihpet 4
 ACPI high precision event timer
+.It Xr acpihve 4
+Hyper-V entropy
 .It Xr acpimadt 4
 ACPI APIC configuration
 .It Xr acpimcfg 4
diff --git a/share/man/man4/acpihve.4 b/share/man/man4/acpihve.4
new file mode 100644
index 00000000000..5cbdedd713c
--- /dev/null
+++ b/share/man/man4/acpihve.4
@@ -0,0 +1,37 @@
+.\"	$OpenBSD: acpihve.4,v 1.1 2017/01/10 08:54:14 jsg Exp $
+.\"
+.\" Copyright (c) 2017 Jonathan Gray <jsg@openbsd.org>
+.\"
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.\"
+.Dd $Mdocdate: January 10 2017 $
+.Dt ACPIHVE 4
+.Os
+.Sh NAME
+.Nm acpihve
+.Nd Hyper-V entropy
+.Sh SYNOPSIS
+.Cd "acpihve* at acpi?"
+.Sh DESCRIPTION
+Hyper-V hosts make entropy available to guests in the OEM0 ACPI table.
+The
+.Nm
+driver feeds this entropy into the kernel's entropy pool.
+.Sh SEE ALSO
+.Xr acpi 4 ,
+.Xr add_true_randomness 9
+.Sh HISTORY
+The
+.Nm
+driver first appeared in
+.Ox 6.1 .