All of lore.kernel.org
 help / color / mirror / Atom feed
From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
To: Avi Kivity <avi@redhat.com>
Cc: mtosatti@redhat.com, kvm@vger.kernel.org, yoshikawa.takuya@oss.ntt.co.jp
Subject: Re: [PATCH 4/4] KVM: x86 emulator: Avoid pushing back ModRM byte in decode_opcode()
Date: Tue, 24 Apr 2012 23:27:36 +0900	[thread overview]
Message-ID: <20120424232736.91d7c5fe3ae27393ac41f36d@gmail.com> (raw)
In-Reply-To: <4F96B440.1030106@redhat.com>

On Tue, 24 Apr 2012 17:10:08 +0300
Avi Kivity <avi@redhat.com> wrote:

> > +	if (!modrm_fetched && (ctxt->d & ModRM))
> > +		ctxt->modrm = insn_fetch(u8, ctxt);
> 
> Instead of adding yet another conditional, how about doing something like
> 
>    if ((c->d & ModRM) || (gtype == Group) || (gtype == GroupDual))
>           ctxt->modrm = insn_fetch(u8, ctxt);
> 
> somewhere early?

Looks nicer than mine.

> In fact even that is too much.  All groups have ModRM somewhere in their
> encoding; all we have to do is move it to the main tables (opcode_table
> or twobyte_table) and just move the existing modrm fetch before group
> parsing.

I see.

Then, the best way to go seems to be drop patch-4 and work on the ModRM
fetch issue separately.

Modifying the tables needs some care.

Thanks,
	Takuya

  reply	other threads:[~2012-04-24 14:27 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-23 15:31 [PATCH 0/4] KVM: x86 emulator: Split decoder into separate functions Takuya Yoshikawa
2012-04-23 15:33 ` [PATCH 1/4] KVM: x86 emulator: Introduce ctxt->op_prefix for 0x66 prefix Takuya Yoshikawa
2012-04-23 15:34 ` [PATCH 2/4] KVM: x86 emulator: Make prefix decoding a separate function Takuya Yoshikawa
2012-04-23 15:35 ` [PATCH 3/4] KVM: x86 emulator: Make opcode " Takuya Yoshikawa
2012-04-23 15:37 ` [PATCH 4/4] KVM: x86 emulator: Avoid pushing back ModRM byte in decode_opcode() Takuya Yoshikawa
2012-04-24 14:10   ` Avi Kivity
2012-04-24 14:27     ` Takuya Yoshikawa [this message]
2012-04-24 14:11 ` [PATCH 0/4] KVM: x86 emulator: Split decoder into separate functions Avi Kivity
2012-04-24 14:41   ` Takuya Yoshikawa

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20120424232736.91d7c5fe3ae27393ac41f36d@gmail.com \
    --to=takuya.yoshikawa@gmail.com \
    --cc=avi@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=mtosatti@redhat.com \
    --cc=yoshikawa.takuya@oss.ntt.co.jp \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.