When a PCI device is gone, we don't want to send IO to it if we can
avoid it. We expose functionality via the irq_chip structure. As
users of that structure may not know about the underlying PCI device,
it's our responsibility to guard against removed devices.
irq_write_msi_msg is already guarded. pci_msi_(un)mask_irq are not.
Guard them for completeness.
For example, surprise removal of a PCIe device triggers teardown. This
touches the irq_chips ops some point to disable the interrupts. I/O
generated here can crash the system on machines with buggy firmware.
Not triggering the IO in the first place eliminates the problem.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
---
There's another patch by Lukas Wunner that is needed (not yet published)
in order to fully block IO on SURPRISE!!! removal. The existing code only
sets the PCI_DEV_DISCONNECTED bit in an unreasonably narrow set of
circumstances. Lukas' patch fixes that.
However, this change is otherwise fully independent, and enjoy!
drivers/pci/msi.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 4d88afdfc843..5f47b5cb0401 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -227,6 +227,9 @@ static void msi_set_mask_bit(struct irq_data *data, u32 flag)
{
struct msi_desc *desc = irq_data_get_msi_desc(data);
+ if (pci_dev_is_disconnected(msi_desc_to_pci_dev(desc)))
+ return;
+
if (desc->msi_attrib.is_msix) {
msix_mask_irq(desc, flag);
readl(desc->mask_base); /* Flush write to device */
--
2.17.1
