pci: fix corrupted pci conf index register by unaligned write

Commit d0ed8076cbdc261 converted the PCI config access to the memory
API, but also inadvertantly changed it to accept unaligned writes,
and corrupt the index register in the process.  This causes a regression
booting NetBSD.

Fix by ignoring unaligned or non-dword writes.

https://bugs.launchpad.net/qemu/+bug/897771

Reported-by: Andreas Gustafsson <gson@gson.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/pci_host.c b/hw/pci_host.c
index 44c6c207a9fc1ebd23f3de795efe8fbec0bd38f5..804177891a6e36f801ed5a8d68e62a8b468fb534 100644 (file)
--- a/hw/pci_host.c
+++ b/hw/pci_host.c
@@ -101,6 +101,9 @@ static void pci_host_config_write(void *opaque, target_phys_addr_t addr,
 
     PCI_DPRINTF("%s addr " TARGET_FMT_plx " len %d val %"PRIx64"\n",
                 __func__, addr, len, val);
+    if (addr != 0 || len != 4) {
+        return;
+    }
     s->config_reg = val;
 }