| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
[Xen-devel] Re: Illegal PV kernel pfm/pfn translations on PROT_NONE iore
|
To: |
Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
|
Subject: |
[Xen-devel] Re: Illegal PV kernel pfm/pfn translations on PROT_NONE ioremaps |
|
From: |
"Stephen C. Tweedie" <sct@xxxxxxxxxx> |
|
Date: |
Wed, 19 Mar 2008 17:12:45 +0000 |
|
Cc: |
"xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx> |
|
Delivery-date: |
Wed, 19 Mar 2008 10:13:19 -0700 |
|
Envelope-to: |
www-data@xxxxxxxxxxxxxxxxxx |
|
In-reply-to: |
<C406F2E1.1E252%keir.fraser@xxxxxxxxxxxxx> |
|
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> |
|
Organization: |
Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903 |
|
References: |
<C406F2E1.1E252%keir.fraser@xxxxxxxxxxxxx> |
|
Sender: |
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
Hi,
On Wed, 2008-03-19 at 16:42 +0000, Keir Fraser wrote:
> > It might be easier to do this at the pte_machine_to_phys level instead,
> > where we can potentially take advantage of other bits of the pte to
> > encode the special casing.
>
> Oh yes, the PAGE_IO type of trick I mentioned in my other email just now.
Yep. There are a number of bits that could be used: for example, I
don't think PROT_WRITE is ever going to be set on a PROT_NONE page,
either.
But...
> SIF_PRIVILEGED is no longer used. It's still set for dom0, but not for
> hardware-capable domUs. It's tricky anyway, since a domU can be given
> hardware capabilities after it has booted through mechanisms like
> pciback-pcifront PCI hotplug.
Right; but I still think it's reasonable to expect this sort of thing to
be declared in advance for a domain. We clearly cannot enter a non-
translating mode dynamically, because of the risk of already having
untranslated PROT_NONE ptes in the page tables. But becoming unable to
save or migrate a guest is a Big Thing, and it would seem not
unreasonable to ask for a startup flag such as SIF_PRIVILEGED to be
declared in advance before we permit that.
I'll probably do a quick patch based in SIF_INITDOMAIN for now, simply
to be able to test whether it does in fact fix the symptoms we're
seeing; but that might not be the best solution to merge long term.
Cheers,
Stephen
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home