From: "Tian, Kevin" <kevin.tian@intel.com>
To: Peter Xu <peterx@redhat.com>, Lu Baolu <baolu.lu@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Sun, Yi Y" <yi.y.sun@intel.com>,
David Woodhouse <dwmw2@infradead.org>
Subject: RE: [RFC PATCH 0/4] Use 1st-level for DMA remapping in guest
Date: Wed, 25 Sep 2019 07:21:51 +0000 [thread overview]
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19D58F4A3@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20190925065640.GO28074@xz-x1>
> From: Peter Xu [mailto:peterx@redhat.com]
> Sent: Wednesday, September 25, 2019 2:57 PM
>
> On Wed, Sep 25, 2019 at 10:48:32AM +0800, Lu Baolu wrote:
> > Hi Kevin,
> >
> > On 9/24/19 3:00 PM, Tian, Kevin wrote:
> > > > > > '-----------'
> > > > > > '-----------'
> > > > > >
> > > > > > This patch series only aims to achieve the first goal, a.k.a using
> > > first goal? then what are other goals? I didn't spot such information.
> > >
> >
> > The overall goal is to use IOMMU nested mode to avoid shadow page
> table
> > and VMEXIT when map an gIOVA. This includes below 4 steps (maybe not
> > accurate, but you could get the point.)
> >
> > 1) GIOVA mappings over 1st-level page table;
> > 2) binding vIOMMU 1st level page table to the pIOMMU;
> > 3) using pIOMMU second level for GPA->HPA translation;
> > 4) enable nested (a.k.a. dual stage) translation in host.
> >
> > This patch set aims to achieve 1).
>
> Would it make sense to use 1st level even for bare-metal to replace
> the 2nd level?
>
> What I'm thinking is the DPDK apps - they have MMU page table already
> there for the huge pages, then if they can use 1st level as the
> default device page table then it even does not need to map, because
> it can simply bind the process root page table pointer to the 1st
> level page root pointer of the device contexts that it uses.
>
Then you need bear with possible page faults from using CPU page
table, while most devices don't support it today.
Thanks
Kevin
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next prev parent reply other threads:[~2019-09-25 7:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-23 12:24 [RFC PATCH 0/4] Use 1st-level for DMA remapping in guest Lu Baolu
2019-09-23 12:24 ` [RFC PATCH 1/4] iommu/vt-d: Move domain_flush_cache helper into header Lu Baolu
2019-09-23 12:24 ` [RFC PATCH 2/4] iommu/vt-d: Add first level page table interfaces Lu Baolu
2019-09-23 20:31 ` Raj, Ashok
2019-09-24 1:38 ` Lu Baolu
2019-09-25 4:30 ` Peter Xu
2019-09-25 4:38 ` Tian, Kevin
2019-09-25 5:24 ` Peter Xu
2019-09-25 6:52 ` Lu Baolu
2019-09-25 7:32 ` Tian, Kevin
2019-09-25 8:35 ` Peter Xu
2019-09-26 1:42 ` Lu Baolu
2019-09-25 5:21 ` Peter Xu
2019-09-26 2:35 ` Lu Baolu
2019-09-26 3:49 ` Peter Xu
2019-09-27 2:27 ` Lu Baolu
2019-09-27 5:34 ` Peter Xu
2019-09-28 8:23 ` Lu Baolu
2019-09-29 5:25 ` Peter Xu
2019-10-08 2:20 ` Lu Baolu
2019-09-23 12:24 ` [RFC PATCH 3/4] iommu/vt-d: Map/unmap domain with mmmap/mmunmap Lu Baolu
2019-09-25 5:00 ` Tian, Kevin
2019-09-25 7:06 ` Lu Baolu
2019-09-23 12:24 ` [RFC PATCH 4/4] iommu/vt-d: Identify domains using first level page table Lu Baolu
2019-09-25 6:50 ` Peter Xu
2019-09-25 7:35 ` Tian, Kevin
2019-09-23 19:27 ` [RFC PATCH 0/4] Use 1st-level for DMA remapping in guest Jacob Pan
2019-09-23 20:25 ` Raj, Ashok
2019-09-24 4:40 ` Lu Baolu
2019-09-24 7:00 ` Tian, Kevin
2019-09-25 2:48 ` Lu Baolu
2019-09-25 6:56 ` Peter Xu
2019-09-25 7:21 ` Tian, Kevin [this message]
2019-09-25 7:45 ` Peter Xu
2019-09-25 8:02 ` Tian, Kevin
2019-09-25 8:52 ` Peter Xu
2019-09-26 1:37 ` Lu Baolu
2019-09-24 4:27 ` Lu Baolu
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