Re: [Xen-devel] page fault handling in Xen

To:	Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] page fault handling in Xen
From:	jeet <jeet_sat12@xxxxxxxxxxx>
Date:	Tue, 6 Mar 2007 18:46:17 +0530 (IST)
Cc:	xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date:	Tue, 06 Mar 2007 05:15:22 -0800
Domainkey-signature:	a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.in; h=X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=zf72wqbuV4zxBHdxfNIL1ibfN2+lIokKWr9aCl8MkIkpAwXl+NB0+DcKIOfMYm8fQHy+MfHGYEil1+ULsRihaFTPopf/N8QsDTkdtT/ienNzKr6S+MeEzq9EALomVZnutdZRnZrQg44QQl0zgDpy/5oSBXbQwI3Zj2HswmSb7Sw=;
Envelope-to:	www-data@xxxxxxxxxxxxxxxxxx
List-help:	<mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id:	Xen developer discussion <xen-devel.lists.xensource.com>
List-post:	<mailto:xen-devel@lists.xensource.com>
List-subscribe:	<http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe:	<http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender:	xen-devel-bounces@xxxxxxxxxxxxxxxxxxx


>Above code will execute and in inner unlikely condition will be true as PT
> table is read only and  error is write_access
> and control will go to not_a_shadow_fault?
> 
> so when the emulation code would be executed for the write that has been
> performed on read only guest PT for adding entry in
> guest page table by guest?
> 
> Have I missed some thing here in understanding

| Yes: guest PTs are mapped with write permissions in the guest PTs. It's only
| in the shadow PTs that the guest PTs are mapped read-only. The test on
| accumulated_gflags is looking at the access permissions in the guest PTs.
|
| -- Keir


Does this mean that on every new entry in level 4 guest page table will cause 
recursive page faults 

to create all the entries from level 4 till level 1 shadow page table?

Jeet

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel





                
__________________________________________________________
Yahoo! India Answers: Share what you know. Learn something new
http://in.answers.yahoo.com/

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

WARNING - OLD ARCHIVES

xen-devel

Re: [Xen-devel] page fault handling in Xen