linux-kernel - Re: [PATCH v3 1/7] iommu/vt-d: Use non-privileged mode for all PASIDs

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Date:   Sat, 1 Apr 2023 21:41:13 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>, iommu@...ts.linux.dev,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Joerg Roedel <joro@...tes.org>, dmaengine@...r.kernel.org,
        vkoul@...nel.org
Cc:     baolu.lu@...ux.intel.com, Will Deacon <will@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        "Zanussi, Tom" <tom.zanussi@...el.com>
Subject: Re: [PATCH v3 1/7] iommu/vt-d: Use non-privileged mode for all PASIDs

On 2023/4/1 7:11, Jacob Pan wrote:
> Supervisor Request Enable (SRE) bit in a PASID entry is for permission
> checking on DMA requests. When SRE = 0, DMA with supervisor privilege
> will be blocked. However, for in-kernel DMA this is not necessary in that
> we are targeting kernel memory anyway. There's no need to differentiate
> user and kernel for in-kernel DMA.
> 
> Let's use non-privileged (user) permission for all PASIDs used in kernel,
> it will be consistent with DMA without PASID (RID_PASID) as well.
> 
> Signed-off-by: Jacob Pan<jacob.jun.pan@...ux.intel.com>

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu