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Message-ID: <3aa28716-9d91-321a-0e52-58ae425ac598@linux.intel.com>
Date: Wed, 31 Aug 2022 08:57:05 +0800
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Cc: baolu.lu@linux.intel.com, Raj Ashok <ashok.raj@intel.com>,
 Thomas Gleixner <tglx@linutronix.de>, Dave Hansen <dave.hansen@intel.com>,
 Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
 "Tian, Kevin" <kevin.tian@intel.com>, Yi Liu <yi.l.liu@intel.com>
Subject: Re: [PATCH 2/2] iommu: Use the user PGD for SVA if PTI is enabled
Content-Language: en-US
To: Jacob Pan <jacob.jun.pan@linux.intel.com>,
 LKML <linux-kernel@vger.kernel.org>, iommu@lists.linux.dev, x86@kernel.org,
 Joerg Roedel <joro@8bytes.org>
References: <20220822201213.352289-1-jacob.jun.pan@linux.intel.com>
 <20220822201213.352289-3-jacob.jun.pan@linux.intel.com>
From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <20220822201213.352289-3-jacob.jun.pan@linux.intel.com>
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On 8/23/22 4:12 AM, Jacob Pan wrote:
> With page table isolation, the kernel manages two sets of page tables
> for each process: one for user one for kernel. When enabling SVA, the
> current x86 IOMMU drivers bind device and PASID with the kernel copy
> of the process page table.
> 
> While there is no known "Meltdown" type of DMA attack, exposing
> kernel mapping to DMA intended for userspace makes the system vulnerable
> unnecessarily. It also breaks the intention of PTI.
> 
> This patch replaces kernel page table PGD with the user counterpart,
> thus fulfill the promise of PTI on the DMA side.
> 
> Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com>

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

Best regards,
baolu