[PATCH] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Dexuan Cui <decui@microsoft.com>]

For a Linux VM with a NVIDIA GPU running on Hyper-V, before the GPU driver
is installed, hibernating the VM will trigger a panic: if the GPU driver
is not installed and loaded, MSI-X/MSI is not enabled on the device, so
pdev->dev.msi.data is NULL, and msi_lock_descs(&pdev->dev) causes the
NULL pointer dereference. Fix this by checking pdev->dev.msi.data.

Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/pci/controller/pci-hyperv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 2d93d0c4f10d..fdd01bfb8e10 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
 	struct msi_desc *entry;
 	int ret = 0;
 
+	if (!pdev->dev.msi.data)
+		return 0;
+
 	msi_lock_descs(&pdev->dev);
 	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
 		irq_data = irq_get_irq_data(entry->irq);
-- 
2.25.1