PCI: Enable INTx in pci_reenable_device() only when MSI/MSI-X not enabled

Andreas reported that after 1f42db786b14 ("PCI: Enable INTx if BIOS left
them disabled"), pciehp surprise removal stopped working.

This happens because pci_reenable_device() on the hotplug bridge (used in
the pciehp_configure_device() path) clears the Interrupt Disable bit, which
apparently breaks the bridge's MSI hotplug event reporting.

Previously we cleared the Interrupt Disable bit in do_pci_enable_device(),
which is used by both pci_enable_device() and pci_reenable_device().  But
we use pci_reenable_device() after the driver may have enabled MSI or
MSI-X, and we *set* Interrupt Disable as part of enabling MSI/MSI-X.

This patch clears Interrupt Disable only when MSI/MSI-X has not been
enabled.

Fixes: 1f42db786b14 PCI: Enable INTx if BIOS left them disabled
Link: https://bugzilla.kernel.org/show_bug.cgi?id=71691
Reported-and-tested-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org
CC: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6b05f6134b68..fdbc294821e6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1192,6 +1192,9 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
                 return err;
         pci_fixup_device(pci_fixup_enable, dev);
 
+        if (dev->msi_enabled || dev->msix_enabled)
+                return 0;
+
         pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
         if (pin) {
                 pci_read_config_word(dev, PCI_COMMAND, &cmd);