From e23fe873b24f0ea5b3083964bb9d583a9a68a650 Mon Sep 17 00:00:00 2001
From: Rebecca Cran <bcran@FreeBSD.org>
Date: Tue, 31 Mar 2020 02:36:39 +0000
Subject: [PATCH] Bhyve: fix SMBIOS Type 17 table generation

According to the SMBIOS specification (revision 2.7 or newer), the
extended module size field should only be used for sizes that can't
fit in the older size field.

Reviewed by:	rgrimes, grehan, jhb
Differential Revision:	https://reviews.freebsd.org/D24107
---
 usr.sbin/bhyve/smbiostbl.c | 41 ++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/usr.sbin/bhyve/smbiostbl.c b/usr.sbin/bhyve/smbiostbl.c
index f7b2d527ca52..8cfd095c3beb 100644
--- a/usr.sbin/bhyve/smbiostbl.c
+++ b/usr.sbin/bhyve/smbiostbl.c
@@ -255,7 +255,7 @@ struct smbios_table_type17 {
 	uint16_t		errhand;	/* handle of mem error data */
 	uint16_t		twidth;		/* total width in bits */
 	uint16_t		dwidth;		/* data width in bits */
-	uint16_t		size;		/* size in bytes */
+	uint16_t		size;		/* size in kb or mb */
 	uint8_t			form;		/* form factor */
 	uint8_t			set;		/* set */
 	uint8_t			dloc;		/* device locator string */
@@ -268,7 +268,7 @@ struct smbios_table_type17 {
 	uint8_t			asset;		/* asset tag string */
 	uint8_t			part;		/* part number string */
 	uint8_t			attributes;	/* attributes */
-	uint32_t		xsize;		/* extended size in mbs */
+	uint32_t		xsize;		/* extended size in mb */
 	uint16_t		curspeed;	/* current speed in mhz */
 	uint16_t		minvoltage;	/* minimum voltage */
 	uint16_t		maxvoltage;	/* maximum voltage */
@@ -444,7 +444,7 @@ struct smbios_table_type17 smbios_type17_template = {
 	-1,		/* handle of memory error data */
 	64,		/* total width in bits including ecc */
 	64,		/* data width in bits */
-	0x7fff,		/* size in bytes (0x7fff=use extended)*/
+	0,		/* size in kb or mb (0x7fff=use extended)*/
 	SMBIOS_MDFF_UNKNOWN,
 	0,		/* set (0x00=none, 0xff=unknown) */
 	1,		/* device locator string */
@@ -695,20 +695,39 @@ smbios_type17_initializer(struct smbios_structure *template_entry,
     uint16_t *n, uint16_t *size)
 {
 	struct smbios_table_type17 *type17;
+	uint64_t memsize, size_KB, size_MB;
 
 	smbios_generic_initializer(template_entry, template_strings,
 	    curaddr, endaddr, n, size);
 	type17 = (struct smbios_table_type17 *)curaddr;
 	type17->arrayhand = type16_handle;
-	type17->xsize = guest_lomem;
 
-	if (guest_himem > 0) {
-		curaddr = *endaddr;
-		smbios_generic_initializer(template_entry, template_strings,
-		    curaddr, endaddr, n, size);
-		type17 = (struct smbios_table_type17 *)curaddr;
-		type17->arrayhand = type16_handle;
-		type17->xsize = guest_himem;
+	memsize = guest_lomem + guest_himem;
+	size_KB = memsize / 1024;
+	size_MB = memsize / MB;
+
+	/* A single Type 17 entry can't represent more than ~2PB RAM */
+	if (size_MB > 0x7FFFFFFF) {
+		printf("Warning: guest memory too big for SMBIOS Type 17 table: "
+			"%luMB greater than max supported 2147483647MB\n", size_MB);
+
+		size_MB = 0x7FFFFFFF;
+	}
+
+	/* See SMBIOS 2.7.0 section 7.18 - Memory Device (Type 17) */
+	if (size_KB <= 0x7FFF) {
+		/* Can represent up to 32767KB with the top bit set */
+		type17->size = size_KB | (1 << 15);
+	} else if (size_MB < 0x7FFF) {
+		/* Can represent up to 32766MB with the top bit unset */
+		type17->size = size_MB & 0x7FFF;
+	} else {
+		type17->size = 0x7FFF;
+		/*
+		 * Can represent up to 2147483647MB (~2PB)
+		 * The top bit is reserved
+		 */
+		type17->xsize = size_MB & 0x7FFFFFFF;
 	}
 
 	return (0);