linux-kernel - Re: [RFC PATCH 11/34] iommu: Split off default domain allocation from group assignment

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Message-ID: <20200414152752.GC14731@8bytes.org>
Date:   Tue, 14 Apr 2020 17:27:52 +0200
From:   "joro@...tes.org" <joro@...tes.org>
To:     "Derrick, Jonathan" <jonathan.derrick@...el.com>
Cc:     "heiko@...ech.de" <heiko@...ech.de>,
        "kgene@...nel.org" <kgene@...nel.org>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "will@...nel.org" <will@...nel.org>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "krzk@...nel.org" <krzk@...nel.org>,
        "robdclark@...il.com" <robdclark@...il.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "gerald.schaefer@...ibm.com" <gerald.schaefer@...ibm.com>,
        "agross@...nel.org" <agross@...nel.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "jroedel@...e.de" <jroedel@...e.de>
Subject: Re: [RFC PATCH 11/34] iommu: Split off default domain allocation
 from group assignment

Hi Jonathan,

On Mon, Apr 13, 2020 at 10:10:50PM +0000, Derrick, Jonathan wrote:
> I had to add the following for initial VMD support. The new PCIe domain
> added on VMD endpoint probe didn't have the dev_iommu member set on the
> VMD subdevices, which I'm guessing is due to probe_iommu_group already
> having been run on the VMD endpoint's group prior to those subdevices
> being added.
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 8a5e1ac328dd..ac1e4fb9bf48 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1577,6 +1577,9 @@ static int iommu_bus_notifier(struct notifier_block *nb,
>         if (action == BUS_NOTIFY_ADD_DEVICE) {
>                 int ret;
>  
> +               if (!dev_iommu_get(dev))
> +                       return -ENOMEM;
> +
>                 ret = iommu_probe_device(dev);
>                 return (ret) ? NOTIFY_DONE : NOTIFY_OK;
>         } else if (action == BUS_NOTIFY_REMOVED_DEVICE) {

Right, thanks for catching this. The hotplug path does not allocate the
dev->iommu structure yet. I'll have to figure out if the above patch
adds it at the right place, but I'll fix it in the next version.

Thanks again,

	Joerg