On 05/07/2012 01:12 PM, Joerg Roedel wrote: > On Sun, May 06, 2012 at 11:21:52AM +0300, Avi Kivity wrote: > > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > > > index d4bf50c..1b516ec 100644 > > > --- a/arch/x86/kvm/emulate.c > > > +++ b/arch/x86/kvm/emulate.c > > > @@ -3937,6 +3937,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) > > > struct opcode opcode; > > > > > > ctxt->memop.type = OP_NONE; > > > + ctxt->memop.val = 0; > > > ctxt->memopp = NULL; > > > ctxt->_eip = ctxt->eip; > > > ctxt->fetch.start = ctxt->_eip; > > > > This only works for long sized values - it doesn't initialize val64 on > > i386, for example. So I think it's better to change bsr (and family) to > > use emualte_2op_SrcV_nobyte() instead (which has the added benefit of > > using the same values as the processor for the "undefined" bits). > > Right, thats a better solution. How about the attached patch? The zf > check shouldn't be necessary anymore because the generated assembly uses > dst.val as input and output so writeback shouldn't do anything wrong. > The bsr and bsf unittests all pass again with this patch. > > Joerg > > From e9262f18e90111d32b584084c0b5564cbd728d65 Mon Sep 17 00:00:00 2001 > From: Joerg Roedel <joerg.roedel@xxxxxxx> > Date: Mon, 7 May 2012 12:05:28 +0200 > Subject: [PATCH] KVM: X86: convert bsf/bsr instructions to > emulate_2op_SrcV_nobyte() > > The instruction emulation for bsrw is broken in KVM because > the code always uses bsr with 32 or 64 bit operand size for > emulation. Fix that by using emulate_2op_SrcV_nobyte() macro > to use guest operand size for emulation. > It looks fine. Do you know what triggered this regression? (for figuring out if it's 3.4 material) -- error compiling committee.c: too many arguments to function -- 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
