From: George Dunlap <dunlapg@umich.edu>
To: AnhNN <ngocanh198@gmail.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: Question about MMU update on HVM guest
Date: Wed, 18 May 2016 12:39:51 +0100 [thread overview]
Message-ID: <CAFLBxZY+Q4BCb4oC5esLYPswQGM_TZZCVEdgktF8Du8ey9yVwQ@mail.gmail.com> (raw)
In-Reply-To: <CAP6KD3hpHjvccRCAUR8cT0T0Bj27VR2P-iO_oPJvqLMDfCDK3Q@mail.gmail.com>
On Fri, May 13, 2016 at 12:11 AM, AnhNN <ngocanh198@gmail.com> wrote:
> Hi,
>
> I have some questions about MMU update operation.
> I add some logging in function do_mmu_update (in file /xen/arch/x86/mm.c),
> and start Windows 7 32 bit HVM guest.
> After guest started, I look at log and see that MMU update has been called
> with every page of guest, with pt_ower = 0 and pg_owner = 1. And with every
> page, MMU update called 2 times. The first time, page->count_info =
> 0x8000000000000002 after MMU update, but after that it decrease to
> 0x8000000000000001 in a different function. At the second time,
> page->count_info = 0x8000000000000002 after MMU update, and keep that value
> forever.
>
> So the question is, why domain 0 have a reference to every pages of HVM
> guest ?
> And why in the second time of MMU update, count_info doesn't decrease to
> 0x8000000000000001 ?
I think your best best for understanding where the references are
coming from is to look at the get_page / put_page.
One question: is your guest running in HVM mode, or in shadow mode?
-George
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
prev parent reply other threads:[~2016-05-18 11:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-12 23:11 Question about MMU update on HVM guest AnhNN
2016-05-18 11:39 ` George Dunlap [this message]
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=CAFLBxZY+Q4BCb4oC5esLYPswQGM_TZZCVEdgktF8Du8ey9yVwQ@mail.gmail.com \
--to=dunlapg@umich.edu \
--cc=ngocanh198@gmail.com \
--cc=xen-devel@lists.xensource.com \
/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;
as well as URLs for NNTP newsgroup(s).