From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: emulator: Only allow VMCALL/VMMCALL trapped by #UD Date: Mon, 07 Jan 2008 11:22:43 +0200 Message-ID: <4781EF63.4010201@qumranet.com> References: <200801040936.08670.sheng.yang@intel.com> <478093F0.6060003@qumranet.com> <200801071021.12038.sheng.yang@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Eric Liu To: "Yang, Sheng" Return-path: In-Reply-To: <200801071021.12038.sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Yang, Sheng wrote: >> I have a vague plan for improving decode; basically extend the decode >> tables to add group decoding. We add a bit to opcode_table and >> twobyte_table that is set for all instructions which need group >> decoding. When the bit is set, the rest of the value in opcode_table is >> interpreted as an index (together with modrm_reg) into a new >> group_table, so we can have different decoding for such instructions. >> > > I also have tried to propose a table for Grp opcode, but can't find a easy > way. Using the rest of the value in opcode_table is a good idea, but I'm > afraid the same value for different group exists, e.g. 0x82(Grp1) and 0xc0 > (Grp2) got the same value as: ByteOp | DstMem | SrcImm | ModRM. If we add > more factors to this, it would become unclear and more tricky, the table also > may become larger... > > Currently, if we want to using group_table, I think the straightforward way is > better: another big "switch"... The only exception is 1a, and we may use 0 > instead of it. > Not sure what you mean. I thought of adding code like if (c->d & Group) { c->group = c->d & GroupMask; // fetch modrm_reg c->d = group_table[c->group * 8 + modrm_reg]; } Instruction execution could continue to be in the regular switch, but the decode flags can be different for every instruction in the group. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/