In x86, you cannot MOV-sreg to memory is either 16-bits or 64-bits. When destination is registers, and the operand size is 32-bits, the high 16-bits in modern CPUs is filled with zero. In contrast, KVM may write to memory 32-bits on MOV-sreg. This patch fixes KVM behavior, and sets the destination operand size to two, if the destination is memory. Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> --- arch/x86/kvm/emulate.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 273c37e..f456783 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3187,6 +3187,8 @@ static int em_mov_rm_sreg(struct x86_emulate_ctxt *ctxt) return emulate_ud(ctxt); ctxt->dst.val = get_segment_selector(ctxt, ctxt->modrm_reg); + if (ctxt->dst.bytes == 4 && ctxt->dst.type == OP_MEM) + ctxt->dst.bytes = 2; return X86EMUL_CONTINUE; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
