[PATCH v2 1/4] pci: disable msi/msix at probe time

From: Michael S. Tsirkin
Date: Thu Mar 19 2015 - 14:58:14 EST


commit d52877c7b1afb8c37ebe17e2005040b79cb618b0
pci/irq: let pci_device_shutdown to call pci_msi_shutdown v2

attempted to address the problem of kexec getting
started after linux enabled msi/msix for a device,
and drivers being confused by msi being enabled,
by disabling msi at shutdown.

But arguably, it's better to disable msi/msix when kexec
starts - for example, kexec might run after a crash (kdump)
and shutdown callbacks are not always invoked in that case.

Cc: Yinghai Lu <yhlu.kernel.send@xxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Cc: Fam Zheng <famz@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
drivers/pci/pci-driver.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 3cb2210..2ebd2a8 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -305,6 +305,12 @@ static long local_pci_probe(void *_ddi)
*/
pm_runtime_get_sync(dev);
pci_dev->driver = pci_drv;
+ /*
+ * When using kexec, msi might be left enabled by the previous kernel,
+ * this breaks things as some drivers assume msi/msi-x is off at boot.
+ * Fix this by forcing msi off at startup.
+ */
+ pci_msi_off(pci_dev);
rc = pci_drv->probe(pci_dev, ddi->id);
if (!rc)
return rc;
--
MST

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