From: Paul Durrant <Paul.Durrant@citrix.com>
To: 'Jan Beulich' <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>,
Kevin Tian <kevin.tian@intel.com>,
George Dunlap <George.Dunlap@citrix.com>
Subject: Re: [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops
Date: Wed, 12 Sep 2018 09:30:02 +0000 [thread overview]
Message-ID: <a1a3bec472394b4f9ec2cf6ee4f557d2@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <5B98DA8902000078001E7B4E@prv1-mh.provo.novell.com>
> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: 12 September 2018 10:21
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: George Dunlap <George.Dunlap@citrix.com>; Kevin Tian
> <kevin.tian@intel.com>; xen-devel <xen-devel@lists.xenproject.org>
> Subject: RE: [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops
>
> >>> On 12.09.18 at 11:15, <Paul.Durrant@citrix.com> wrote:
> >> -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@suse.com]
> >> Sent: 12 September 2018 10:13
> >> To: Paul Durrant <Paul.Durrant@citrix.com>
> >> Cc: George Dunlap <George.Dunlap@citrix.com>; Kevin Tian
> >> <kevin.tian@intel.com>; xen-devel <xen-devel@lists.xenproject.org>
> >> Subject: RE: [PATCH v6 08/14] vtd: add lookup_page method to
> iommu_ops
> >>
> >> >>> On 12.09.18 at 11:05, <Paul.Durrant@citrix.com> wrote:
> >> >> From: Jan Beulich [mailto:JBeulich@suse.com]
> >> >> Sent: 12 September 2018 10:03
> >> >>
> >> >> A HVM guest using the PV IOMMU is quite fine, but it shouldn't talk to
> >> >> it in terms of MFNs.
> >> >>
> >> >
> >> > Well, it has to talk MFNs at some level, surely? The output of the
> IOMMU is
> >> > not subject to EPT/NPT, right?
> >>
> >> Yes to the second question, but no to the first: The GFN -> MFN
> translation
> >> should still be done inside Xen in the HVM case, imo (in the course of
> >> manufacturing the PTE).
> >
> > Indeed. This function is very much internal to Xen (it's simply an
> > abstraction on top of a vendor implementation), so why should it not work
> in
> > terms of MFNs?
>
> Because "MFN" is a concept a HVM guest is not knowing about, or
> supposed to be knowing. The only time where (part of) it might
> legitimately (have to) know is when it comes to managing the host
> (including any guests), i.e. in the tool stack of a PVH Dom0.
Ok. So consider validating a PV-IOMMU unmap request from an HVM guest. It passes in a DFN and a GFN belonging to itself. Now Xen needs to figure out whether that BFN actually maps to the GFN. It can look up the MFN backing the GFN (from the p2m). How does Xen now validate it if it cannot lookup what MFN is actually present in the PTE referenced by the DFN?
Paul
>
> Jan
>
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2018-09-12 9:30 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 9:46 [PATCH v6 00/14] paravirtual IOMMU interface Paul Durrant
2018-08-23 9:46 ` [PATCH v6 01/14] iommu: introduce the concept of BFN Paul Durrant
2018-08-30 15:59 ` Jan Beulich
2018-09-03 8:23 ` Paul Durrant
2018-09-03 11:46 ` Jan Beulich
2018-09-04 6:48 ` Tian, Kevin
2018-09-04 8:32 ` Jan Beulich
2018-09-04 8:37 ` Tian, Kevin
2018-09-04 8:47 ` Jan Beulich
2018-09-04 8:49 ` Paul Durrant
2018-09-04 9:08 ` Jan Beulich
2018-09-05 0:42 ` Tian, Kevin
2018-09-05 6:48 ` Jan Beulich
2018-09-05 6:56 ` Tian, Kevin
2018-09-05 7:11 ` Jan Beulich
2018-09-05 9:13 ` Paul Durrant
2018-09-05 9:38 ` Jan Beulich
2018-09-06 10:36 ` Paul Durrant
2018-09-06 13:13 ` Jan Beulich
2018-09-06 14:54 ` Paul Durrant
2018-09-07 1:47 ` Tian, Kevin
2018-09-07 6:24 ` Jan Beulich
2018-09-07 8:13 ` Paul Durrant
2018-09-07 8:16 ` Tian, Kevin
2018-09-07 8:25 ` Paul Durrant
2018-08-23 9:46 ` [PATCH v6 02/14] iommu: make use of type-safe BFN and MFN in exported functions Paul Durrant
2018-09-04 10:29 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 03/14] iommu: push use of type-safe BFN and MFN into iommu_ops Paul Durrant
2018-09-04 10:32 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 04/14] iommu: don't domain_crash() inside iommu_map/unmap_page() Paul Durrant
2018-09-04 10:38 ` Jan Beulich
2018-09-04 10:39 ` Paul Durrant
2018-08-23 9:47 ` [PATCH v6 05/14] public / x86: introduce __HYPERCALL_iommu_op Paul Durrant
2018-09-04 11:50 ` Jan Beulich
2018-09-04 12:23 ` Paul Durrant
2018-09-04 12:55 ` Jan Beulich
2018-09-04 13:17 ` Paul Durrant
2018-09-07 10:52 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 06/14] iommu: track reserved ranges using a rangeset Paul Durrant
2018-09-07 10:40 ` Jan Beulich
2018-09-11 9:28 ` Paul Durrant
2018-08-23 9:47 ` [PATCH v6 07/14] x86: add iommu_op to query reserved ranges Paul Durrant
2018-09-07 11:01 ` Jan Beulich
2018-09-11 9:34 ` Paul Durrant
2018-09-11 9:43 ` Jan Beulich
2018-09-13 6:11 ` Tian, Kevin
2018-08-23 9:47 ` [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops Paul Durrant
2018-09-07 11:11 ` Jan Beulich
2018-09-07 12:36 ` Paul Durrant
2018-09-07 14:56 ` Jan Beulich
2018-09-07 15:24 ` Paul Durrant
2018-09-07 15:52 ` Jan Beulich
2018-09-12 8:31 ` Paul Durrant
2018-09-12 8:43 ` Jan Beulich
2018-09-12 8:45 ` Paul Durrant
2018-09-12 8:51 ` Paul Durrant
2018-09-12 8:53 ` Paul Durrant
2018-09-12 9:03 ` Jan Beulich
2018-09-12 9:05 ` Paul Durrant
2018-09-12 9:12 ` Jan Beulich
2018-09-12 9:15 ` Paul Durrant
2018-09-12 9:21 ` Jan Beulich
2018-09-12 9:30 ` Paul Durrant [this message]
2018-09-12 10:07 ` Jan Beulich
2018-09-12 10:09 ` Paul Durrant
2018-09-12 12:15 ` Jan Beulich
2018-09-12 12:22 ` Paul Durrant
2018-09-12 12:39 ` Jan Beulich
2018-09-12 12:53 ` Paul Durrant
2018-09-12 13:19 ` Jan Beulich
2018-09-12 13:25 ` Paul Durrant
2018-09-12 13:39 ` Jan Beulich
2018-09-12 13:43 ` Paul Durrant
2018-09-12 8:59 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 09/14] mm / iommu: include need_iommu() test in iommu_use_hap_pt() Paul Durrant
2018-09-07 11:20 ` Jan Beulich
2018-09-11 9:39 ` Paul Durrant
2018-09-11 9:47 ` Jan Beulich
2018-09-13 6:23 ` Tian, Kevin
2018-09-13 8:34 ` Paul Durrant
2018-08-23 9:47 ` [PATCH v6 10/14] mm / iommu: split need_iommu() into has_iommu_pt() and need_iommu_pt_sync() Paul Durrant
2018-08-23 11:10 ` Razvan Cojocaru
2018-09-11 14:31 ` Jan Beulich
2018-09-11 15:40 ` Paul Durrant
2018-09-12 6:45 ` Jan Beulich
2018-09-12 8:07 ` Paul Durrant
2018-08-23 9:47 ` [PATCH v6 11/14] x86: add iommu_op to enable modification of IOMMU mappings Paul Durrant
2018-09-11 14:48 ` Jan Beulich
2018-09-11 15:52 ` Paul Durrant
2018-09-12 6:53 ` Jan Beulich
2018-09-12 8:04 ` Paul Durrant
2018-08-23 9:47 ` [PATCH v6 12/14] memory: add get_paged_gfn() as a wrapper Paul Durrant
2018-08-23 10:24 ` Julien Grall
2018-08-23 10:30 ` Paul Durrant
2018-09-11 14:56 ` Jan Beulich
2018-09-12 9:10 ` Paul Durrant
2018-09-12 9:15 ` Jan Beulich
2018-09-12 10:01 ` George Dunlap
2018-09-12 10:08 ` Paul Durrant
2018-09-12 10:10 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 13/14] x86: add iommu_ops to modify and flush IOMMU mappings Paul Durrant
2018-09-11 15:15 ` Jan Beulich
2018-09-12 7:03 ` Jan Beulich
2018-09-12 8:02 ` Paul Durrant
2018-09-12 8:27 ` Jan Beulich
2018-09-13 6:41 ` Tian, Kevin
2018-09-13 8:32 ` Paul Durrant
2018-09-13 8:49 ` Jan Beulich
2018-08-23 9:47 ` [PATCH v6 14/14] x86: extend the map and unmap iommu_ops to support grant references Paul Durrant
2018-09-12 14:12 ` Jan Beulich
2018-09-12 16:28 ` Paul Durrant
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=a1a3bec472394b4f9ec2cf6ee4f557d2@AMSPEX02CL03.citrite.net \
--to=paul.durrant@citrix.com \
--cc=George.Dunlap@citrix.com \
--cc=JBeulich@suse.com \
--cc=kevin.tian@intel.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 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).