[PATCH RFC v4 08/21] nvme-pci: Handle movable BARs

[Sergey Miroshnichenko]

Hotplugged devices can affect the existing ones by moving their BARs.
PCI subsystem will inform the NVME driver about this by invoking
reset_prepare()+reset_done(), then iounmap()+ioremap() must be called.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
---
 drivers/nvme/host/pci.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 92bad1c810ac..ccea3033a67a 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -106,6 +106,7 @@ struct nvme_dev {
 	unsigned int num_vecs;
 	int q_depth;
 	u32 db_stride;
+	resource_size_t current_phys_bar;
 	void __iomem *bar;
 	unsigned long bar_mapped_size;
 	struct work_struct remove_work;
@@ -1672,13 +1673,16 @@ static int nvme_remap_bar(struct nvme_dev *dev, unsigned long size)
 {
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 
-	if (size <= dev->bar_mapped_size)
+	if (dev->bar &&
+	    dev->current_phys_bar == pci_resource_start(pdev, 0) &&
+	    size <= dev->bar_mapped_size)
 		return 0;
 	if (size > pci_resource_len(pdev, 0))
 		return -ENOMEM;
 	if (dev->bar)
 		iounmap(dev->bar);
-	dev->bar = ioremap(pci_resource_start(pdev, 0), size);
+	dev->current_phys_bar = pci_resource_start(pdev, 0);
+	dev->bar = ioremap(dev->current_phys_bar, size);
 	if (!dev->bar) {
 		dev->bar_mapped_size = 0;
 		return -ENOMEM;
@@ -2504,6 +2508,8 @@ static void nvme_reset_work(struct work_struct *work)
 	if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING))
 		goto out;
 
+	nvme_remap_bar(dev, db_bar_size(dev, 0));
+
 	/*
 	 * If we're called to reset a live controller first shut it down before
 	 * moving on.
@@ -2910,6 +2916,23 @@ static void nvme_error_resume(struct pci_dev *pdev)
 	flush_work(&dev->ctrl.reset_work);
 }
 
+void nvme_rescan_prepare(struct pci_dev *pdev)
+{
+	struct nvme_dev *dev = pci_get_drvdata(pdev);
+
+	nvme_dev_disable(dev, false);
+	nvme_dev_unmap(dev);
+	dev->bar = NULL;
+}
+
+void nvme_rescan_done(struct pci_dev *pdev)
+{
+	struct nvme_dev *dev = pci_get_drvdata(pdev);
+
+	nvme_dev_map(dev);
+	nvme_reset_ctrl_sync(&dev->ctrl);
+}
+
 static const struct pci_error_handlers nvme_err_handler = {
 	.error_detected	= nvme_error_detected,
 	.slot_reset	= nvme_slot_reset,
@@ -2974,6 +2997,8 @@ static struct pci_driver nvme_driver = {
 	},
 	.sriov_configure = pci_sriov_configure_simple,
 	.err_handler	= &nvme_err_handler,
+	.rescan_prepare	= nvme_rescan_prepare,
+	.rescan_done	= nvme_rescan_done,
 };
 
 static int __init nvme_init(void)
-- 
2.20.1