linux-kernel - Re: [PATCH v2] Enhance dmar to support device hotplug

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Date:	Tue, 10 Dec 2013 12:03:25 -0500
From:	Don Dutile <ddutile@...hat.com>
To:	Yijing Wang <wangyijing@...wei.com>
CC:	Alex Williamson <alex.williamson@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Joerg Roedel <joro@...tes.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Vinod Koul <vinod.koul@...el.com>,
	linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
	Hanjun Guo <guohanjun@...wei.com>, dmaengine@...r.kernel.org,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v2] Enhance dmar to support device hotplug

On 11/21/2013 03:21 AM, Yijing Wang wrote:
> This is the v2 patch, the v1 link: http://marc.info/?l=linux-pci&m=138364004628824&w=2
>
> v1->v2: keep (pci_dev *) pointer array in dmar_drhd_uni, only use pci device id
> 		to update pci_dev * pointer info during device hotplug in intel iommu
> 		driver notifier.
>
> Currently, DMAR driver save target pci devices pointers for drhd/rmrr/atsr
> in (pci_dev *) array, but never update these info after initialization.
> It's not safe, because pci devices maybe hot added or removed during
> system running. They will have new pci_dev * pointer. So if there have
> two IOMMUs or more in system, these devices will find a wrong drhd during
> DMA mapping. And DMAR faults will occur. This patch save pci device id
> as well as (pci_dev *) to fix this issue. Pci device id will be used to update
> pci_dev * poninter during device hotplug in intel iommu driver notifier.
> Other, here use list to manage target devices for IOMMU,
> we can easily use list helper.
>
> Yijing Wang (1):
>    IOMMU: enhance dmar to support device hotplug
>
>   drivers/iommu/dmar.c        |   82 +++++++++++-----------
>   drivers/iommu/intel-iommu.c |  161 +++++++++++++++++++++++++++++-------------
>   include/linux/dmar.h        |   24 ++++--
>   3 files changed, 167 insertions(+), 100 deletions(-)
>
>
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>

Can this bug & fix be demonstrated by configuring & de-configuring VFs
on an SRIOV device, since that effectively looks like a hot-add & hot-remove ?

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