linux-kernel - Re: [PATCH v2 1/1] iommu/vt-d: Fix kdump kernels boot failure with scalable mode

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Message-ID: <8f1c7e64-efdc-eff5-8dea-470f4ada5f73@linux.intel.com>
Date:   Tue, 23 Aug 2022 14:23:58 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     iommu@...ts.linux.dev
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Wen Jin <wen.jin@...el.com>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v2 1/1] iommu/vt-d: Fix kdump kernels boot failure with
 scalable mode

On 2022/8/17 09:10, Lu Baolu wrote:
> The translation table copying code for kdump kernels is currently based
> on the extended root/context entry formats of ECS mode defined in older
> VT-d v2.5, and doesn't handle the scalable mode formats. This causes
> the kexec capture kernel boot failure with DMAR faults if the IOMMU was
> enabled in scalable mode by the previous kernel.
> 
> The ECS mode has already been deprecated by the VT-d spec since v3.0 and
> Intel IOMMU driver doesn't support this mode as there's no real hardware
> implementation. Hence this converts ECS checking in copying table code
> into scalable mode.
> 
> The existing copying code consumes a bit in the context entry as a mark
> of copied entry. This marker needs to work for the old format as well as
> for extended context entries. It's hard to find such a bit for both
> legacy and scalable mode context entries. This replaces it with a per-
> IOMMU bitmap.
> 
> Fixes: 7373a8cc38197 ("iommu/vt-d: Setup context and enable RID2PASID support")
> Cc:stable@...r.kernel.org
> Reported-by: Jerry Snitselaar<jsnitsel@...hat.com>
> Tested-by: Wen Jin<wen.jin@...el.com>
> Signed-off-by: Lu Baolu<baolu.lu@...ux.intel.com>

This patch has been queued:

https://lore.kernel.org/linux-iommu/20220823061557.1631056-1-baolu.lu@linux.intel.com/

Best regards,
baolu