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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: kevin.tian@intel.com, ashok.raj@intel.com, kvm@vger.kernel.org,
	sanjay.k.kumar@intel.com, yi.y.sun@intel.com,
	iommu@lists.linux-foundation.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: Tue, 24 Sep 2019 12:27:11 +0800
Message-ID: <f94a67e3-58c4-2318-3b7a-86c0fadfca49@linux.intel.com> (raw)
In-Reply-To: <20190923122715.53de79d0@jacob-builder>

Hi Jacob,

On 9/24/19 3:27 AM, Jacob Pan wrote:
> Hi Baolu,
> 
> On Mon, 23 Sep 2019 20:24:50 +0800
> Lu Baolu <baolu.lu@linux.intel.com> wrote:
> 
>> This patchset aims to move IOVA (I/O Virtual Address) translation
>> to 1st-level page table under scalable mode. The major purpose of
>> this effort is to make guest IOVA support more efficient.
>>
>> As Intel VT-d architecture offers caching-mode, guest IOVA (GIOVA)
>> support is now implemented in a shadow page manner. The device
>> simulation software, like QEMU, has to figure out GIOVA->GPA mapping
>> and writes to a shadowed page table, which will be used by pIOMMU.
>> Each time when mappings are created or destroyed in vIOMMU, the
>> simulation software will intervene. The change on GIOVA->GPA will be
>> shadowed to host, and the pIOMMU will be updated via VFIO/IOMMU
>> interfaces.
>>
>>
>>       .-----------.
>>       |  vIOMMU   |
>>       |-----------|                 .--------------------.
>>       |           |IOTLB flush trap |        QEMU        |
>>       .-----------. (map/unmap)     |--------------------|
>>       | GVA->GPA  |---------------->|      .----------.  |
>>       '-----------'                 |      | GPA->HPA |  |
>>       |           |                 |      '----------'  |
>>       '-----------'                 |                    |
>>                                     |                    |
>>                                     '--------------------'
>>                                                  |
>>              <------------------------------------
>>              |
>>              v VFIO/IOMMU API
>>        .-----------.
>>        |  pIOMMU   |
>>        |-----------|
>>        |           |
>>        .-----------.
>>        | GVA->HPA  |
>>        '-----------'
>>        |           |
>>        '-----------'
>>
>> In VT-d 3.0, scalable mode is introduced, which offers two level
>> translation page tables and nested translation mode. Regards to
>> GIOVA support, it can be simplified by 1) moving the GIOVA support
>> over 1st-level page table to store GIOVA->GPA mapping in vIOMMU,
>> 2) binding vIOMMU 1st level page table to the pIOMMU, 3) using pIOMMU
>> second level for GPA->HPA translation, and 4) enable nested (a.k.a.
>> dual stage) translation in host. Compared with current shadow GIOVA
>> support, the new approach is more secure and software is simplified
>> as we only need to flush the pIOMMU IOTLB and possible device-IOTLB
>> when an IOVA mapping in vIOMMU is torn down.
>>
>>       .-----------.
>>       |  vIOMMU   |
>>       |-----------|                 .-----------.
>>       |           |IOTLB flush trap |   QEMU    |
>>       .-----------.    (unmap)      |-----------|
>>       | GVA->GPA  |---------------->|           |
>>       '-----------'                 '-----------'
>>       |           |                       |
>>       '-----------'                       |
>>             <------------------------------
>>             |      VFIO/IOMMU
>>             |  cache invalidation and
>>             | guest gpd bind interfaces
>>             v
> For vSVA, the guest PGD bind interface will mark the PASID as guest
> PASID and will inject page request into the guest. In FL gIOVA case, I
> guess we are assuming there is no page fault for GIOVA. I will need to
> add a flag in the gpgd bind such that any PRS will be auto responded
> with invalid.

There should be no page fault. The pages should have been pinned.

> 
> Also, native use of IOVA FL map is not to be supported? i.e. IOMMU API
> and DMA API for native usage will continue to be SL only?

Yes. There isn't such use case as far as I can see.

Best regards,
Baolu

>>       .-----------.
>>       |  pIOMMU   |
>>       |-----------|
>>       .-----------.
>>       | GVA->GPA  |<---First level
>>       '-----------'
>>       | GPA->HPA  |<---Scond level
>>       '-----------'
>>       '-----------'
>>
>> This patch series only aims to achieve the first goal, a.k.a using
>> first level translation for IOVA mappings in vIOMMU. I am sending
>> it out for your comments. Any comments, suggestions and concerns are
>> welcomed.
>>
> 
> 
>> Based-on-idea-by: Ashok Raj <ashok.raj@intel.com>
>> Based-on-idea-by: Kevin Tian <kevin.tian@intel.com>
>> Based-on-idea-by: Liu Yi L <yi.l.liu@intel.com>
>> Based-on-idea-by: Lu Baolu <baolu.lu@linux.intel.com>
>> Based-on-idea-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
>>
>> Lu Baolu (4):
>>    iommu/vt-d: Move domain_flush_cache helper into header
>>    iommu/vt-d: Add first level page table interfaces
>>    iommu/vt-d: Map/unmap domain with mmmap/mmunmap
>>    iommu/vt-d: Identify domains using first level page table
>>
>>   drivers/iommu/Makefile             |   2 +-
>>   drivers/iommu/intel-iommu.c        | 142 ++++++++++--
>>   drivers/iommu/intel-pgtable.c      | 342
>> +++++++++++++++++++++++++++++ include/linux/intel-iommu.h        |
>> 31 ++- include/trace/events/intel_iommu.h |  60 +++++
>>   5 files changed, 553 insertions(+), 24 deletions(-)
>>   create mode 100644 drivers/iommu/intel-pgtable.c
>>
> 
> [Jacob Pan]
> 
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      parent reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23 12:24 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
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 [this message]

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