PCI/PM: Print config space of devices before suspend

When resuming from hibernation (S4, also known as "suspend to disk") on a
VM, we have seen invalid config space, e.g.,

  serial 0000:00:16.3: restoring config space at offset 0x14 (was 0x9104e000, writing 0xffffffff)

To help debug problems like this, log the config space being saved before
suspend, similar to the log in pci_restore_config_dword() when resuming.

Link: https://lore.kernel.org/r/20200113060724.19571-1-yu.c.chen@intel.com
[bhelgaas: commit log]
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Len Brown <lenb@kernel.org>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e87196cc1a7fba33d37661ad0f73ca1dd1418583..34cde70440c321325b777b367e246a06c5c1d311 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1372,8 +1372,11 @@ int pci_save_state(struct pci_dev *dev)
 {
        int i;
        /* XXX: 100% dword access ok here? */
-       for (i = 0; i < 16; i++)
+       for (i = 0; i < 16; i++) {
                pci_read_config_dword(dev, i * 4, &dev->saved_config_space[i]);
+               pci_dbg(dev, "saving config space at offset %#x (reading %#x)\n",
+                       i * 4, dev->saved_config_space[i]);
+       }
        dev->state_saved = true;
 
        i = pci_save_pcie_state(dev);