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From: Avi Kivity <>
To: Linus Torvalds <>
	Alistair John Strachan <>,
	Avi Kivity <>
Subject: [PATCH RESEND] KVM: x86 emulator: fix debug reg mov instructions
Date: Sun,  5 Aug 2007 10:16:11 +0300	[thread overview]
Message-ID: <> (raw)

More fallout from the writeback fixes: debug register transfer instructions
do their own writeback and thus need to disable the general writeback
mechanism.  This fixes oopses and some guest failures on AMD machines (the
Intel variant decodes the instruction in hardware and thus does not need

Cc: Alistair John Strachan <>
Signed-off-by: Avi Kivity <>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 1f979cb..4b8a0cc 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -1217,11 +1217,13 @@ twobyte_insn:
 	case 0x21: /* mov from dr to reg */
+		no_wb = 1;
 		if (modrm_mod != 3)
 			goto cannot_emulate;
 		rc = emulator_get_dr(ctxt, modrm_reg, &_regs[modrm_rm]);
 	case 0x23: /* mov from reg to dr */
+		no_wb = 1;
 		if (modrm_mod != 3)
 			goto cannot_emulate;
 		rc = emulator_set_dr(ctxt, modrm_reg, _regs[modrm_rm]);

                 reply	other threads:[~2007-08-05  7:16 UTC|newest]

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