All of lore.kernel.org
 help / color / mirror / Atom feed
From: Paul Durrant <Paul.Durrant@citrix.com>
To: 'Jan Beulich' <JBeulich@suse.com>
Cc: "xen-devel (xen-devel@lists.xenproject.org)"
	<xen-devel@lists.xenproject.org>
Subject: Re: get_page_from_gfn() for foreign pages
Date: Thu, 1 Mar 2018 16:06:11 +0000	[thread overview]
Message-ID: <62cc97efe1754d48ba1c3c5d49897e9f@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <5A982F2702000078001AD744@prv-mh.provo.novell.com>

> -----Original Message-----
[snip]
> >> And then you didn't really answer my question.
> >
> > Well, you can't revoke a grant whist a backend has it mapped... that's been
> > a limitation forever. Also, I think it's reasonable that granting to a domain
> > A allows domain A *and* any other domain with mapping privilege over
> domain A
> > to access that page. I don't think there's really any expectation in the
> > grant interface that granting to only that domain... frontends have to trust
> > backends and if the backend grants it on then so be it. That's certainly the
> > level of trust that's been in place since v2 and AFAIK no-one is unhappy
> about
> > that.
> 
> All true, but what you want to do here is a mapping outside of
> what grant_table.c controls and provides. Yet for the page owner
> to know when a grant is fine to revoke, such obtaining of extra
> references would need to be tracked.
> 

Ah yes, that's a bit gnarly. I'll have to try to figure out what can be done there.

  Paul

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

      reply	other threads:[~2018-03-01 16:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-01 11:39 get_page_from_gfn() for foreign pages Paul Durrant
2018-03-01 14:00 ` Jan Beulich
2018-03-01 14:17   ` Paul Durrant
2018-03-01 14:31     ` Jan Beulich
2018-03-01 14:49       ` Paul Durrant
2018-03-01 15:49         ` Jan Beulich
2018-03-01 16:06           ` Paul Durrant [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=62cc97efe1754d48ba1c3c5d49897e9f@AMSPEX02CL03.citrite.net \
    --to=paul.durrant@citrix.com \
    --cc=JBeulich@suse.com \
    --cc=xen-devel@lists.xenproject.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 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.