public inbox for kvm@vger.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Avi Kivity <avi@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	kvm@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kvm: optimize ISR lookups
Date: Tue, 22 May 2012 19:26:40 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1205221919260.3231@ionos> (raw)
In-Reply-To: <4FBB7185.6040105@redhat.com>

On Tue, 22 May 2012, Avi Kivity wrote:
> On 05/22/2012 12:04 AM, Thomas Gleixner wrote:
> > The only justification for having the same layout as the actual
> > hardware is when you are going to map the memory into the guest space,
> > which is not the case here.
>
> The APIC page is in fact mapped  to the hardware (not the guest, but vmx
> microcode does access it).  Only one register, the TPR, is ever used. 
> It's possible to re-layout the data structure so that the TPR stays in
> the same place while everything else becomes contiguous, but we'll have
> to do it again if the hardware starts mapping more registers.

I would avoid that by having a compressed version which reflects the
SW state and the mapped one which allows the vmx microcode to fiddle
with the TPR. If you need more registers in the HW page then you don't
have to worry about the layout and just have a proper accessor for
that.

Thanks,

	tglx

  reply	other threads:[~2012-05-22 17:26 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-21 16:37 [PATCH] kvm: optimize ISR lookups Michael S. Tsirkin
2012-05-21 18:44 ` Michael S. Tsirkin
2012-05-21 21:04 ` Thomas Gleixner
2012-05-21 21:51   ` Michael S. Tsirkin
2012-05-21 22:14     ` Thomas Gleixner
2012-05-21 22:24       ` Michael S. Tsirkin
2012-05-21 22:44         ` Thomas Gleixner
2012-05-21 22:50           ` Michael S. Tsirkin
2012-05-21 23:01         ` Thomas Gleixner
2012-05-22 10:46           ` Avi Kivity
2012-05-23 14:48             ` Ingo Molnar
2012-05-23 15:03               ` Avi Kivity
2012-05-23 20:10                 ` Thomas Gleixner
2012-05-23 20:46                   ` Michael S. Tsirkin
2012-05-23 23:02                     ` Thomas Gleixner
2012-05-23 15:14               ` Michael S. Tsirkin
2012-05-23 19:22                 ` H. Peter Anvin
2012-05-21 23:11         ` Thomas Gleixner
2012-05-21 23:06   ` Michael S. Tsirkin
2012-05-21 23:12     ` H. Peter Anvin
2012-05-21 23:36     ` Thomas Gleixner
2012-05-22 10:59   ` Avi Kivity
2012-05-22 17:26     ` Thomas Gleixner [this message]
2012-05-23 15:10       ` Avi Kivity
2012-05-23 18:37         ` Thomas Gleixner
2012-05-23 19:25           ` H. Peter Anvin
2012-05-23 22:00             ` Thomas Gleixner
2012-05-30 14:18               ` Avi Kivity

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=alpine.LFD.2.02.1205221919260.3231@ionos \
    --to=tglx@linutronix.de \
    --cc=avi@redhat.com \
    --cc=hpa@zytor.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=mst@redhat.com \
    --cc=mtosatti@redhat.com \
    --cc=x86@kernel.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox