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

On Fri, 2013-12-13 at 14:02 +1100, Alexey Kardashevskiy wrote:

On 12/13/2013 10:35 AM, Scott Wood wrote:

quoted

On Tue, May 21, 2013 at 01:33:09PM +1000, Alexey Kardashevskiy wrote:

quoted

+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]

quoted

+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 :)

I still get the WARN_ONs even with that patch.  You're still registering
the bus notifier unconditionally.

-Scott