This is a hack specific to my system which I haven't even attempted
to generalize yet. The ATI/AMD Radeon HD5450 VGA BIOS appears to have
a backdoor to determine the physical address of the device. It reads
a value matching the top byte of the I/O Port BAR from a register in
VGA I/O port space then uses in/out to that address during BIOS
execution. On my setup the I/O port BAR is at 0x4000 physically and
emulated for the guest at 0xc0000. So I simply look for this access
and replace 0x40 with 0xc0. That's enough for it to get through BIOS
init, but it's still only partially functional (no VGA text mode).
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
hw/vfio_pci.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
index 846e8de..5db076f 100644
--- a/hw/vfio_pci.c
+++ b/hw/vfio_pci.c
@@ -1041,6 +1041,15 @@ static uint64_t vfio_legacy_read(void *opaque, hwaddr addr, unsigned size)
break;
}
+ /* XXX - Complete hardcoded hack, need to figure out how common this is and
+ * come up with a device quirk and match host phys to guest phys. This is
+ * only known to be needed for an ATI/AMD Radeon HD5450 which stores the
+ * upper byte of the I/O port address in this unused VGA I/O port register.
+ */
+ if (io->region_offset == 0x3c0 && addr == 3 && size == 1 && data == 0x40) {
+ data = 0xc0;
+ }
+
DPRINTF("%s(0x%"HWADDR_PRIx", %d) = 0x%"PRIx64"\n",
__func__, io->region_offset + addr, size, data);
--
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