xen: Add support for XenServer 6.1 platform device

On XenServer on Windows machine a platform device with ID 2 instead of
1 is used.

This device is mainly identical to device 1 but due to some Windows
update behaviour it was decided to use a device with a different ID.

This causes compatibility issues with Linux which expects, if Xen
is detected, to find a Xen platform device (5853:0001) otherwise code
will crash due to some missing initialization (specifically grant
tables). Specifically from dmesg

RIP: 0010:gnttab_expand+0x29/0x210
Code: 90 0f 1f 44 00 00 55 31 d2 48 89 e5 41 57 41 56 41 55 41 89 fd
41 54 53 48 83 ec 10 48 8b 05 7e 9a 49 02 44 8b 35 a7 9a 49 02
<8b> 48 04 8d 44 39 ff f7 f1 45 8d 24 06 89 c3 e8 43 fe ff ff
44 39
RSP: 0000:ffffba34c01fbc88 EFLAGS: 00010086
...

The device 2 is presented by Xapi adding device specification to
Qemu command line.

Signed-off-by: Frediano Ziglio <[e-mail]>
Acked-by: Juergen Gross <[e-mail]>
Message-ID: <[e-mail]>
Signed-off-by: Juergen Gross <[e-mail]>

drivers/xen/platform-pci.c

···
 
 #define DRV_NAME    "xen-platform-pci"
 
+#define PCI_DEVICE_ID_XEN_PLATFORM_XS61	0x0002
+
 static unsigned long platform_mmio;
 static unsigned long platform_mmio_alloc;
 static unsigned long platform_mmiolen;
···
 
 static const struct pci_device_id platform_pci_tbl[] = {
 	{PCI_VENDOR_ID_XEN, PCI_DEVICE_ID_XEN_PLATFORM,
+		PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
+	{PCI_VENDOR_ID_XEN, PCI_DEVICE_ID_XEN_PLATFORM_XS61,
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
 	{0,}
 };