Re: [RFC] [PATCH V4 0/3] Add IOMMU support.

["Duran, Leo" <leo.duran@amd.com>]

Hi Yao,
We're OK so far (as noted below).
Leo

From: Yao, Jiewen [mailto:jiewen.yao@intel.com]
Sent: Tuesday, May 02, 2017 8:33 PM
To: Duran, Leo <leo.duran@amd.com>; edk2-devel@lists.01.org
Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Singh, Brijesh <brijesh.singh@amd.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: RE: [RFC] [PATCH V4 0/3] Add IOMMU support.

It is a good question.

I did consider that before.
In our scenario, we need support VTd dynamic opt-in/opt-out. I hope to keep all these logic inside of VTd driver.
If we need a default path-through driver, a platform need more complex logic to decide when to run the default pass-through and when to run the real VTd driver. It is a burden.

I think we do use optional protocols in PciBus driver (such as EFI_INCOMPATIBLE_PCI_DEVICE_SUPPORT_PROTOCOL, EFI_PCI_PLATFORM_PROTOCOL, EFI_PCI_OVERRIDE_PROTOCOL)

In V4, I am using protocol notification for PciHostBridge, so that we do not need locate IOMMU protocol at each function call.
Do you run into any issue on using protocol notification?
[Duran, Leo] Nope, no issues found as of yet.

Thank you
Yao Jiewen


From: Duran, Leo [mailto:leo.duran@amd.com]
Sent: Wednesday, May 3, 2017 2:42 AM
To: Yao, Jiewen <jiewen.yao@intel.com<mailto:jiewen.yao@intel.com>>; edk2-devel@lists.01.org<mailto:edk2-devel@lists.01.org>
Cc: Ni, Ruiyu <ruiyu.ni@intel.com<mailto:ruiyu.ni@intel.com>>; Singh, Brijesh <brijesh.singh@amd.com<mailto:brijesh.singh@amd.com>>; Ard Biesheuvel <ard.biesheuvel@linaro.org<mailto:ard.biesheuvel@linaro.org>>
Subject: RE: [RFC] [PATCH V4 0/3] Add IOMMU support.

Hi Yao,

Would it make sense to have a default protocol producer driver that provides pass-thru functionality?
This way consumers of the protocol may add a dependency on it, ensuring that the protocol provider always run first.
(In the SEV sample driver we run first because we added the driver to the APRIORI list, but it seems like a Depex would be more elegant)

Leo.

> -----Original Message-----
> From: Jiewen Yao [mailto:jiewen.yao@intel.com]
> Sent: Saturday, April 29, 2017 8:51 AM
> To: edk2-devel@lists.01.org<mailto:edk2-devel@lists.01.org>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com<mailto:ruiyu.ni@intel.com>>; Duran, Leo <leo.duran@amd.com<mailto:leo.duran@amd.com>>;
> Singh, Brijesh <brijesh.singh@amd.com<mailto:brijesh.singh@amd.com>>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org<mailto:ard.biesheuvel@linaro.org>>
> Subject: [RFC] [PATCH V4 0/3] Add IOMMU support.
>
> ================ V4 ==============
> Refine the EDKII_IOMMU_PROTOCOL.
>
> 1) Add AllocateBuffer/FreeBuffer/Map/Unmap() API.
> They are similar to DmaLib in EmbeddedPkg and similar to the previous
> BmDmaLib (by leo.duran@amd.com<mailto:leo.duran@amd.com>).
>
> These APIs are invoked by PciHostBridge driver to allocate DMA memory.
>
> The PciHostBridge driver (IOMMU consumer) is simplified:
> It uses IOMMU, if IOMMU protocol is present.
> Else it uses original logic.
>
> 2) Add SetMappingAttribute() API.
> It is similar to SetAttribute() API in V1.
>
> This API is invoked by PciBus driver to set DMA access attribute (read/write)
> for device.
>
> The PciBus driver (IOMMU consumer) is simplified:
> It sets access attribute in Map/Unmap,
> if IOMMU protocol is present.
>
> 3) Remove SetRemapAddress/GetRemapAddress() API.
> Because PciHostBridge/PciBus can call the APIs defined above, there is no
> need to provide remap capability.
>
> -- Sample producer drivers:
> 1) The sample VTd driver (IOMMU producer) is at
> https://github.com/jyao1/edk2/tree/dma_v4/IntelSiliconPkg/IntelVTdDxe
>
> It is added to show the concept. It is not fully implemented yet.
> It will not be checked in in this patch.
>
> 2) The sample AMD SEV driver (IOMMU producer) is at
> https://github.com/jyao1/edk2/tree/dma_v4/IntelSiliconPkg/SampleAmdSe
> vDxe
> (code is borrowed from leo.duran@amd.com<mailto:leo.duran@amd.com> and brijesh.singh@amd.com<mailto:brijesh.singh@amd.com>)
>
> This is not a right place to put this driver.
>
> It is added to show the concept.
> It is not fully implemented. It will not be checked in.
> Please do not use it directly.
>
> 3) The sample STYX driver (IOMMU producer) is at
> https://github.com/jyao1/edk2/tree/dma_v4/IntelSiliconPkg/SampleStyxDx
> e
> (code is borrowed from ard.biesheuvel@linaro.org<mailto:ard.biesheuvel@linaro.org>)
>
> This is not a right place to put this driver.
>
> It is added to show the concept.
> It is not fully implemented. It will not be checked in.
> Please do not use it directly.
>
>
> ================ V3 ==============
> 1) Add Remap capability (from Ard Biesheuvel) Add
> EDKII_IOMMU_REMAP_ADDRESS API in IOMMU_PROTOCOL.
>
> NOTE: The code is not fully validated yet.
> The purpose is to collect feedback to decide the next step.
>
> ================ V2 ==============
> 1) Enhance Unmap() in PciIo (From Ruiyu Ni) Maintain a local list of MapInfo
> and match it in Unmap.
>
> 2) CopyMem for ReadOperation in PciIo after SetAttribute (Leo Duran) Fix a
> bug in V1 that copy mem for read happen before SetAttribute, which will
> break AMD SEV solution.
>
> ================ V1 ==============
>
> This patch series adds IOMMU protocol and updates the consumer to
> support IOMMU based DMA access in UEFI.
>
> This patch series can support the BmDmaLib request for AMD SEV.
> submitted by Duran, Leo <leo.duran@amd.com<mailto:leo.duran@amd.com>> and Brijesh Singh
> <brijesh.ksingh@gmail.com<mailto:brijesh.ksingh@gmail.com>>.
> https://lists.01.org/pipermail/edk2-devel/2017-March/008109.html, and
> https://lists.01.org/pipermail/edk2-devel/2017-March/008820.html.
> We can have an AMD SEV specific IOMMU driver to produce IOMMU
> protocol, and clear SEV in IOMMU->SetAttribute().
>
> This patch series can also support Intel VTd based DMA protection,
> requested by Jiewen Yao <jiewen.yao@intel.com<mailto:jiewen.yao@intel.com>>, discussed in
> https://lists.01.org/pipermail/edk2-devel/2017-March/008157.html.
> We can have an Intel VTd specific IOMMU driver to produce IOMMU
> protocol, and update VTd engine to grant or deny access in IOMMU-
> >SetAttribute().
>
> This patch series does not provide a full Intel VTd driver, which will be
> provide in other patch in the future.
>
> The purpose of this patch series to review if this IOMMU protocol design can
> meet all DMA access and management requirement.
>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com<mailto:ruiyu.ni@intel.com>>
> Cc: Leo Duran <leo.duran@amd.com<mailto:leo.duran@amd.com>>
> Cc: Brijesh Singh <brijesh.singh@amd.com<mailto:brijesh.singh@amd.com>>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org<mailto:ard.biesheuvel@linaro.org>>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Jiewen Yao <jiewen.yao@intel.com<mailto:jiewen.yao@intel.com>>
>
> Jiewen Yao (3):
>   MdeModulePkg/Include: Add IOMMU protocol definition.
>   MdeModulePkg/PciHostBridge: Add IOMMU support.
>   MdeModulePkg/PciBus: Add IOMMU support.
>
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciBus.c                    |   9 +
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciBus.h                    |   1 +
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciBusDxe.inf               |   1 +
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c                     |  37 +++
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c      |  37 +++
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridgeDxe.inf |   2 +
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridge.h      |   2 +
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c    |  61 ++++
>  MdeModulePkg/Include/Protocol/IoMmu.h                      | 310
> ++++++++++++++++++++
>  MdeModulePkg/MdeModulePkg.dec                              |   3 +
>  10 files changed, 463 insertions(+)
>  create mode 100644 MdeModulePkg/Include/Protocol/IoMmu.h
>
> --
> 2.7.4.windows.1