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From: Peter Xu <peterx@redhat.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
	"Sun, Yi Y" <yi.y.sun@intel.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Alex Williamson <alex.williamson@redhat.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 14:56:40 +0800	[thread overview]
Message-ID: <20190925065640.GO28074@xz-x1> (raw)
In-Reply-To: <dfd9b7a2-5553-328a-08eb-16c8a3a2644e@linux.intel.com>

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.

Regards,

-- 
Peter Xu

  reply	other threads:[~2019-09-25  6:56 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 [this message]
2019-09-25  7:21           ` Tian, Kevin
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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