PCI: vmd: Reset VMD config register between soft reboots

VMD driver can disable or enable MSI remapping by changing
VMCONFIG_MSI_REMAP register. This register needs to be set to the
default value during soft reboots. Drives failed to enumerate
when Windows boots after performing a soft reboot from Linux.
Windows doesn't support MSI remapping disable feature and stale
register value hinders Windows VMD driver initialization process.
Adding vmd_shutdown function to make sure to set the VMCONFIG
register to the default value.

Link: https://lore.kernel.org/r/[email protected]
Fixes: ee81ee8 ("PCI: vmd: Disable MSI-X remapping when possible")
Signed-off-by: Nirmal Patel <[email protected]>
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Reviewed-by: Jon Derrick <[email protected]>

Author: Nirmal Patel

drivers/pci/controller/vmd.c

@@ -1036,6 +1036,13 @@ static void vmd_remove(struct pci_dev *dev)
 	ida_simple_remove(&vmd_instance_ida, vmd->instance);
 }
 
+static void vmd_shutdown(struct pci_dev *dev)
+{
+        struct vmd_dev *vmd = pci_get_drvdata(dev);
+
+        vmd_remove_irq_domain(vmd);
+}
+
 #ifdef CONFIG_PM_SLEEP
 static int vmd_suspend(struct device *dev)
 {
@@ -1101,6 +1108,7 @@ static struct pci_driver vmd_drv = {
 	.id_table	= vmd_ids,
 	.probe		= vmd_probe,
 	.remove		= vmd_remove,
+	.shutdown	= vmd_shutdown,
 	.driver		= {
 		.pm	= &vmd_dev_pm_ops,
 	},