linux-kernel - Re: [PATCH] PCIe hot plug for Intel iommu

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Message-ID: <86802c440910220007s5881653o5fbbc810523b18fe@mail.gmail.com>
Date:	Thu, 22 Oct 2009 00:07:11 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
To:	Fenghua Yu <fenghua.yu@...el.com>, jbarnes@...tuousgeek.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	Joerg Roedel <joro@...tes.org>,
	Francois Isabelle <Francois.Isabelle@...kontron.com>,
	iommu <iommu@...ts.linux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCIe hot plug for Intel iommu

On Tue, Oct 6, 2009 at 11:23 AM, Fenghua Yu <fenghua.yu@...el.com> wrote:
> To support PCIe hot plug in IOMMU, we register a notifier to respond to device
> change action.
>
> When the notifier gets BUS_NOTIFY_UNBOUND_DRIVER, it removes the device from its
> DMAR domain.
>
> A hot added device will be added into an IOMMU domain when it first does IOMMU
> op. So there is no need to add more code for hot add.
>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
>
> ---
>
>  intel-iommu.c |   29 +++++++++++++++++++++++++++++
>  1 files changed, 29 insertions(+)
>
> diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
> index 855dd7c..d8b8cfc 100644
> --- a/drivers/pci/intel-iommu.c
> +++ b/drivers/pci/intel-iommu.c
> @@ -3193,6 +3193,33 @@ static int __init init_iommu_sysfs(void)
>  }
>  #endif /* CONFIG_PM */
>
> +/*
> + * Here we only respond to action of unbound device from driver.
> + *
> + * Added device is not attached to its DMAR domain here yet. That will happen
> + * when mapping the device to iova.
> + */
> +static int device_notifier(struct notifier_block *nb,
> +                                 unsigned long action, void *data)
> +{
> +       struct device *dev = data;
> +       struct pci_dev *pdev = to_pci_dev(dev);
> +       struct dmar_domain *domain;
> +
> +       domain = find_domain(pdev);
> +       if (!domain)
> +               return 0;
> +
> +       if (action == BUS_NOTIFY_UNBOUND_DRIVER && !iommu_pass_through)
> +               domain_remove_one_dev_info(domain, pdev);
> +
> +       return 0;
> +}
> +
> +static struct notifier_block device_nb = {
> +       .notifier_call = device_notifier,
> +};
> +
>  int __init intel_iommu_init(void)
>  {
>        int ret = 0;
> @@ -3245,6 +3272,8 @@ int __init intel_iommu_init(void)
>
>        register_iommu(&intel_iommu_ops);
>
> +       bus_register_notifier(&pci_bus_type, &device_nb);
> +
>        return 0;
>  }
>

it seems this one should be get into 2.6.32....and .stable

otherwise second hot plug in the same pcie slot will not work with dma.

YH
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