From: Pekka Enberg <penberg@cs.helsinki.fi>
Date: Fri, 16 Jul 2010 12:44:26 +0000 (+0300)
Subject: kvm: Use proper segment + offset in e820 bios
X-Git-Tag: next-20110824~3^2~528^2~80
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e9d504bb8ff0cf6148d5c26eb3a90caee5ebca86;p=karo-tx-linux.git

kvm: Use proper segment + offset in e820 bios

This patch fixes E820 BIOS emulation on AMD CPUs that, unlike Intel ones,
require proper 16-bit segment/offset addressing in virtualized 16-bit mode.

Reported-by: Asias He <asias.hejun@gmail.com>
Tested-by: Asias He <asias.hejun@gmail.com>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---

diff --git a/tools/kvm/bios/bios-rom.S b/tools/kvm/bios/bios-rom.S
index 0a8e69584c0b..0119c11e52e3 100644
--- a/tools/kvm/bios/bios-rom.S
+++ b/tools/kvm/bios/bios-rom.S
@@ -79,9 +79,6 @@ ENTRY(bios_int15)
 	pushl	%ebx
 	pushl	%eax
 
-	xor	%ax, %ax
-	mov	%ax, %fs
-
 	movl	%esp, %eax
 	call	e820_query_map
 
diff --git a/tools/kvm/bios/e820.c b/tools/kvm/bios/e820.c
index 8d8b1c7a87b9..7f3f86f213b6 100644
--- a/tools/kvm/bios/e820.c
+++ b/tools/kvm/bios/e820.c
@@ -1,8 +1,14 @@
 #include "kvm/e820.h"
 
+#include "kvm/segment.h"
 #include "kvm/bios.h"
 #include "kvm/util.h"
 
+static inline void set_fs(uint16_t seg)
+{
+	asm volatile("movw %0,%%fs" : : "rm" (seg));
+}
+
 static inline uint8_t rdfs8(unsigned long addr)
 {
 	uint8_t v;
@@ -15,23 +21,30 @@ static inline uint8_t rdfs8(unsigned long addr)
 void e820_query_map(struct e820_query *query)
 {
 	uint8_t map_size;
+	uint16_t fs_seg;
 	uint32_t ndx;
 
+	fs_seg		= flat_to_seg16(E820_MAP_SIZE);
+	set_fs(fs_seg);
+
 	ndx		= query->ebx;
 
-	map_size	= rdfs8(E820_MAP_SIZE);
+	map_size	= rdfs8(flat_to_off16(E820_MAP_SIZE, fs_seg));
 
 	if (ndx < map_size) {
 		unsigned long start;
 		unsigned int i;
 		uint8_t *p;
 
+		fs_seg		= flat_to_seg16(E820_MAP_START);
+		set_fs(fs_seg);
+
 		start	= E820_MAP_START + sizeof(struct e820_entry) * ndx;
 
 		p	= (void *) query->edi;
 
 		for (i = 0; i < sizeof(struct e820_entry); i++)
-			*p++	= rdfs8(start + i);
+			*p++	= rdfs8(flat_to_off16(start + i, fs_seg));
 	}
 
 	query->eax	= SMAP;
diff --git a/tools/kvm/include/kvm/segment.h b/tools/kvm/include/kvm/segment.h
new file mode 100644
index 000000000000..0701cd7b4629
--- /dev/null
+++ b/tools/kvm/include/kvm/segment.h
@@ -0,0 +1,16 @@
+#ifndef KVM_SEGMENT_H
+#define KVM_SEGMENT_H
+
+#include <stdint.h>
+
+static inline uint16_t flat_to_seg16(uint32_t address)
+{
+	return address >> 4;
+}
+
+static inline uint16_t flat_to_off16(uint32_t address, uint32_t segment)
+{
+	return address - (segment << 4);
+}
+
+#endif /* KVM_SEGMENT_H */