Subject: Re: [1/3] powerpc/vfio: Enable on POWERNV platform

From: Alexey Kardashevskiy <[email-masked]>
Date: Fri, 13 Dec 2013 14:02:06 +1100

On 12/13/2013 10:35 AM, Scott Wood wrote:
> On Tue, May 21, 2013 at 01:33:09PM +1000, Alexey Kardashevskiy wrote:
>> +static int iommu_add_device(struct device *dev)
>> +{
>> +	struct iommu_table *tbl;
>> +	int ret = 0;
>> +
>> +	if (WARN_ON(dev->iommu_group)) {
>> +		pr_warn("iommu_tce: device %s is already in iommu group %d, skipping\n",
>> +				dev_name(dev),
>> +				iommu_group_id(dev->iommu_group));
>> +		return -EBUSY;
>> +	}
> [snip]
>> +static int __init tce_iommu_init(void)
>> +{
>> +	struct pci_dev *pdev = NULL;
>> +
>> +	BUILD_BUG_ON(PAGE_SIZE < IOMMU_PAGE_SIZE);
>> +
>> +	for_each_pci_dev(pdev)
>> +		iommu_add_device(&pdev->dev);
>> +
>> +	bus_register_notifier(&pci_bus_type, &tce_iommu_bus_nb);
>> +	return 0;
>> +}
>> +
>> +subsys_initcall_sync(tce_iommu_init);
> 
> This is missing a check to see whether the appropriate hardware is
> present.  This file should also be renamed to something less generic, and
> depend on a kconfig symbol more specific than CONFIG_PPC64.
> 
> When this is combined with CONFIG_FSL_PAMU on hardware with a PAMU, I get
> a bunch of those "WARN_ON(dev->iommu_group)" dumps because PAMU already
> got to them.  Presumably without PAMU it silently (or with just pr_debug)
> bails out at some other point.

I posted (yet again) yesterday "[PATCH v11] PPC: POWERNV: move
iommu_add_device earlier" which should fix this. And Bharat asked many
times for this to get accepted :)

-- 
Alexey