From: Aurelien Jarno <aurelien@aurel32.net>
Date: Wed, 25 Jul 2007 08:19:54 +0000 (+0200)
Subject: KVM: disable writeback for 0x0f 0x01 instructions.
X-Git-Tag: kvm-34~36
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=bfa6c62f98bd0602025d7b48e267d817082f5d07;p=users%2Fdwmw2%2Flinux.git

KVM: disable writeback for 0x0f 0x01 instructions.

0x0f 0x01 instructions (ie lgdt, lidt, smsw, lmsw and invlpg) does
not use writeback. This patch set no_wb=1 when emulating those
instructions.

This fixes a regression booting the FreeBSD kernel on AMD.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 21ce977899371..cbbb9c5cfc86f 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -1183,6 +1183,8 @@ pop_instruction:
 twobyte_insn:
 	switch (b) {
 	case 0x01: /* lgdt, lidt, lmsw */
+		/* Disable writeback. */
+		no_wb = 1;
 		switch (modrm_reg) {
 			u16 size;
 			unsigned long address;