[rfc/patch] pv-on-hvm: make netfront grab PCI ressources.

[Gerd Hoffmann <kraxel@suse.de>]

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  Hi,

This patch makes netfront grab the rtl8139 PCI ressources when running
as paravirtualized driver in a HVM domain.  If the driver fails to grab
the ressources it refuses to load.  If it succeeds grabbing the
ressources this shoulld prevent any other driver from taking the device.

This makes sure that we don't have two drivers (8139 pci driver and
netfront) active for the same device.

The device is matched by both pci id and pci subsystem id (which was
added a few days ago), so netfront (aka xen-vnif) will grab a virtual
network card only, not a real rtl8139 card.

As a bonus we'll get driver auto loading support as the modutils are
able now to figure the

Comments?
  Gerd

PS: The same would be good for blkfront too, although there it is less
    critical as only one of the drivers succeeds registering the ide
    major number, so it can't happen that both grab the same disk.

-- 
Gerd Hoffmann <kraxel@suse.de>

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diff -r 780f097b54c5 linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c	Wed Feb 07 17:29:52 2007 +0000
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c	Thu Feb 08 16:44:05 2007 +0100
@@ -2074,8 +2074,97 @@ static struct notifier_block notifier_in
 	.priority       = 0
 };
 
+/* ------------------------------------------------------------------ */
+
+#ifndef CONFIG_XEN
+#include <linux/pci.h>
+
+#define DRV_NAME "netfront"
+
+static int rtl8139_taken = 0;
+
+static void __devexit rtl8139_release(struct pci_dev *pdev)
+{
+	long ioaddr, iolen;
+	long mmio_addr, mmio_len;
+
+	ioaddr = pci_resource_start(pdev, 0);
+	iolen = pci_resource_len(pdev, 0);
+	mmio_addr = pci_resource_start(pdev, 1);
+	mmio_len = pci_resource_len(pdev, 1);
+
+	release_region(ioaddr, iolen);
+	release_mem_region(mmio_addr, mmio_len);
+
+	printk(KERN_INFO DRV_NAME ": released rtl8139 card\n");
+	rtl8139_taken--;
+}
+
+static int __devinit rtl8139_grab(struct pci_dev *pdev,
+				  const struct pci_device_id *ent)
+{
+	int ret;
+	long ioaddr, iolen;
+	long mmio_addr, mmio_len;
+
+	ret = pci_enable_device(pdev);
+	if (ret) {
+		printk(KERN_ERR DRV_NAME ": can't enable device\n");
+		return ret;
+	}
+
+	ioaddr = pci_resource_start(pdev, 0);
+	iolen = pci_resource_len(pdev, 0);
+
+	mmio_addr = pci_resource_start(pdev, 1);
+	mmio_len = pci_resource_len(pdev, 1);
+
+	if (request_mem_region(mmio_addr, mmio_len, DRV_NAME) == NULL)
+	{
+		printk(KERN_ERR DRV_NAME ": MEM I/O resource 0x%lx @ 0x%lx busy\n",
+		       mmio_addr, mmio_len);
+		return -EBUSY;
+	}
+
+	if (request_region(ioaddr, iolen, DRV_NAME) == NULL)
+	{
+		printk(KERN_ERR DRV_NAME ": I/O resource 0x%lx @ 0x%lx busy\n",
+		       iolen, ioaddr);
+		release_mem_region(mmio_addr, mmio_len);
+		return -EBUSY;
+	}
+
+	printk(KERN_INFO DRV_NAME ": grabbed rtl8139 card\n");
+	rtl8139_taken++;
+	return 0;
+}
+
+static struct pci_device_id rtl8139_pci_tbl[] __devinitdata = {
+	{
+		.vendor    = 0x10ec,  // Realtek
+		.device    = 0x8139,  // 8139
+		.subvendor = 0x5853,  // XenSource
+		.subdevice = 0x0001,  // #1
+	},
+	{0,}
+};
+MODULE_DEVICE_TABLE(pci, rtl8139_pci_tbl);
+
+static struct pci_driver rtl8139_grabber = {
+	.name     = DRV_NAME,
+	.probe    = rtl8139_grab,
+	.remove   = __devexit_p(rtl8139_release),
+	.id_table = rtl8139_pci_tbl,
+};
+
+#endif
+
+/* ------------------------------------------------------------------ */
+
 static int __init netif_init(void)
 {
+	int ret;
+	
 	if (!is_running_on_xen())
 		return -ENODEV;
 
@@ -2092,6 +2181,14 @@ static int __init netif_init(void)
 	if (is_initial_xendomain())
 		return 0;
 
+#ifndef CONFIG_XEN
+	ret = pci_module_init(&rtl8139_grabber);
+	if (ret)
+		return ret;
+	if (!rtl8139_taken)
+		return -EBUSY;
+#endif
+
 	IPRINTK("Initialising virtual ethernet driver.\n");
 
 	(void)register_inetaddr_notifier(&notifier_inetdev);
@@ -2108,6 +2205,9 @@ static void __exit netif_exit(void)
 
 	unregister_inetaddr_notifier(&notifier_inetdev);
 
+#ifndef CONFIG_XEN
+	pci_unregister_driver(&rtl8139_grabber);
+#endif
 	return xenbus_unregister_driver(&netfront);
 }
 module_exit(netif_exit);

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