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Message-ID: <20220510143540.GF49344@nvidia.com>
Date: Tue, 10 May 2022 11:35:40 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Joerg Roedel <joro@...tes.org>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>,
Eric Auger <eric.auger@...hat.com>,
Liu Yi L <yi.l.liu@...el.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCH v6 05/12] iommu/vt-d: Remove SVM_FLAG_SUPERVISOR_MODE
support
On Tue, May 10, 2022 at 02:17:31PM +0800, Lu Baolu wrote:
> The current kernel DMA with PASID support is based on the SVA with a flag
> SVM_FLAG_SUPERVISOR_MODE. The IOMMU driver binds the kernel memory address
> space to a PASID of the device. The device driver programs the device with
> kernel virtual address (KVA) for DMA access. There have been security and
> functional issues with this approach:
>
> - The lack of IOTLB synchronization upon kernel page table updates.
> (vmalloc, module/BPF loading, CONFIG_DEBUG_PAGEALLOC etc.)
> - Other than slight more protection, using kernel virtual address (KVA)
> has little advantage over physical address. There are also no use
> cases yet where DMA engines need kernel virtual addresses for in-kernel
> DMA.
>
> This removes SVM_FLAG_SUPERVISOR_MODE support in the Intel IOMMU driver.
> The device driver is suggested to handle kernel DMA with PASID through
> the kernel DMA APIs.
>
> Link: https://lore.kernel.org/linux-iommu/20210511194726.GP1002214@nvidia.com/
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
> drivers/iommu/intel/svm.c | 53 +++++++++------------------------------
> 1 file changed, 12 insertions(+), 41 deletions(-)
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Jason
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