[Xen-devel] [PATCH 2/2] xen-pciback: Allow enabling/disabling expansion ROM

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

From: Dwayne Litzenberger <dlitz@xxxxxxxxx>

Newer AMD GPUs store their initialization routines as bytecode on the
ROM.  This fixes the following initialization error inside the VM when
doing PCI passthrough:

    radeon 0000:00:05.0: Invalid PCI ROM header signature: expecting 0xaa55, 
got 0xffff
    radeon 0000:00:05.0: Invalid PCI ROM header signature: expecting 0xaa55, 
got 0xffff
    [drm:radeon_get_bios [radeon]] *ERROR* Unable to locate a BIOS ROM
    radeon 0000:00:05.0: Fatal error during GPU init

Signed-off-by: Dwayne Litzenberger <dlitz@xxxxxxxxx>
---
 drivers/xen/xen-pciback/conf_space_header.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/xen-pciback/conf_space_header.c 
b/drivers/xen/xen-pciback/conf_space_header.c
index 697d0a8..bc145d3 100644
--- a/drivers/xen/xen-pciback/conf_space_header.c
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -150,21 +150,21 @@ static int rom_write(struct pci_dev *dev, int offset, u32 
value, void *data)
        if ((value | ~PCI_ROM_ADDRESS_MASK) == ~0U)
                bar->which = 1;
        else {
-               u32 tmpval;
-               err = pci_read_config_dword(dev, offset, &tmpval);
+               u32 newval = bar->val;
+
+               /* Allow enabling/disabling rom, if present */
+               if (newval & PCI_ROM_ADDRESS_MASK) {
+                       newval &= ~PCI_ROM_ADDRESS_ENABLE;
+                       newval |= value & PCI_ROM_ADDRESS_ENABLE;
+               }
+
+               err = pci_write_config_dword(dev, offset, newval);
                if (err)
                        goto out;
-               if (tmpval != bar->val && value == bar->val) {
-                       /* Allow restoration of bar value. */
-                       err = pci_write_config_dword(dev, offset, bar->val);
-                       if (err)
-                               goto out;
-               }
+               bar->val = newval;
                bar->which = 0;
        }
 
-       /* Do we need to support enabling/disabling the rom address here? */
-
 out:
        return err;
 }
-- 
git-series 0.9.1

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