From: Alexandru Gagniuc <mr.nuke.me@gmail.com>
To: linux-pci@vger.kernel.org, bhelgaas@google.com
Cc: keith.busch@intel.com, alex_gagniuc@dellteam.com,
austin_bolen@dell.com, shyam_iyer@dell.com, Narendra_K@Dell.com,
Stuart_Hayes@Dell.com, lukas@wunner.de,
Alexandru Gagniuc <mr.nuke.me@gmail.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected
Date: Mon, 30 Jul 2018 16:21:44 -0500 [thread overview]
Message-ID: <20180730212146.31909-1-mr.nuke.me@gmail.com> (raw)
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@gmail.com>
---
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
next reply other threads:[~2018-07-30 21:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-30 21:21 Alexandru Gagniuc [this message]
2018-08-29 16:59 ` [PATCH] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected Alex G.
2018-09-12 21:28 ` Bjorn Helgaas
2018-09-18 13:07 ` Alex_Gagniuc
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