xen, gfx passthrough: retrieve VGA BIOS to work

Now we retrieve VGA bios like kvm stuff in qemu but we need to
fix Device Identification in case if its not matched with the
real IGD device since Seabios is always trying to compare this
ID to work out VGA BIOS.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index 9b3df811b1..3232296bf8 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -109,3 +109,82 @@ int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
 
     return 0;
 }
+
+static void *get_vgabios(XenPCIPassthroughState *s, int *size,
+                       XenHostPCIDevice *dev)
+{
+    return pci_assign_dev_load_option_rom(&s->dev, OBJECT(&s->dev), size,
+                                          dev->domain, dev->bus,
+                                          dev->dev, dev->func);
+}
+
+/* Refer to Seabios. */
+struct rom_header {
+    uint16_t signature;
+    uint8_t size;
+    uint8_t initVector[4];
+    uint8_t reserved[17];
+    uint16_t pcioffset;
+    uint16_t pnpoffset;
+} __attribute__((packed));
+
+struct pci_data {
+    uint32_t signature;
+    uint16_t vendor;
+    uint16_t device;
+    uint16_t vitaldata;
+    uint16_t dlen;
+    uint8_t drevision;
+    uint8_t class_lo;
+    uint16_t class_hi;
+    uint16_t ilen;
+    uint16_t irevision;
+    uint8_t type;
+    uint8_t indicator;
+    uint16_t reserved;
+} __attribute__((packed));
+
+int xen_pt_setup_vga(XenPCIPassthroughState *s, XenHostPCIDevice *dev)
+{
+    unsigned char *bios = NULL;
+    struct rom_header *rom;
+    int bios_size;
+    char *c = NULL;
+    char checksum = 0;
+    uint32_t len = 0;
+    struct pci_data *pd = NULL;
+
+    if (!is_igd_vga_passthrough(dev)) {
+        return -1;
+    }
+
+    bios = get_vgabios(s, &bios_size, dev);
+    if (!bios) {
+        XEN_PT_ERR(&s->dev, "VGA: Can't getting VBIOS!\n");
+        return -1;
+    }
+
+    /* Currently we fixed this address as a primary. */
+    rom = (struct rom_header *)bios;
+    pd = (void *)(bios + (unsigned char)rom->pcioffset);
+
+    /* We may need to fixup Device Identification. */
+    if (pd->device != s->real_device.device_id) {
+        pd->device = s->real_device.device_id;
+
+        len = rom->size * 512;
+        /* Then adjust the bios checksum */
+        for (c = (char *)bios; c < ((char *)bios + len); c++) {
+            checksum += *c;
+        }
+        if (checksum) {
+            bios[len - 1] -= checksum;
+            XEN_PT_LOG(&s->dev, "vga bios checksum is adjusted %x!\n",
+                       checksum);
+        }
+    }
+
+    /* Currently we fixed this address as a primary for legacy BIOS. */
+    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
+    return 0;
+}