[PATCH] PCIe hot plug for Intel iommu

[Fenghua Yu <fenghua.yu@intel.com>]

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@intel.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;
 }