[PATCH v3] sparc/PCI: Fix for panic while enabling SR-IOV

[Babu Moger]

We noticed this panic while enabling SR-IOV in sparc.

mlx4_core: Mellanox ConnectX core driver v2.2-1 (Jan  1 2015)
mlx4_core: Initializing 0007:01:00.0
mlx4_core 0007:01:00.0: Enabling SR-IOV with 5 VFs
mlx4_core: Initializing 0007:01:00.1
Unable to handle kernel NULL pointer dereference
insmod(10010): Oops [#1]
CPU: 391 PID: 10010 Comm: insmod Not tainted
		4.1.12-32.el6uek.kdump2.sparc64 #1
TPC: <dma_supported+0x20/0x80>
I7: <__mlx4_init_one+0x324/0x500 [mlx4_core]>
Call Trace:
 [00000000104c5ea4] __mlx4_init_one+0x324/0x500 [mlx4_core]
 [00000000104c613c] mlx4_init_one+0xbc/0x120 [mlx4_core]
 [0000000000725f14] local_pci_probe+0x34/0xa0
 [0000000000726028] pci_call_probe+0xa8/0xe0
 [0000000000726310] pci_device_probe+0x50/0x80
 [000000000079f700] really_probe+0x140/0x420
 [000000000079fa24] driver_probe_device+0x44/0xa0
 [000000000079fb5c] __device_attach+0x3c/0x60
 [000000000079d85c] bus_for_each_drv+0x5c/0xa0
 [000000000079f588] device_attach+0x88/0xc0
 [000000000071acd0] pci_bus_add_device+0x30/0x80
 [0000000000736090] virtfn_add.clone.1+0x210/0x360
 [00000000007364a4] sriov_enable+0x2c4/0x520
 [000000000073672c] pci_enable_sriov+0x2c/0x40
 [00000000104c2d58] mlx4_enable_sriov+0xf8/0x180 [mlx4_core]
 [00000000104c49ac] mlx4_load_one+0x42c/0xd40 [mlx4_core]
Disabling lock debugging due to kernel taint
Caller[00000000104c5ea4]: __mlx4_init_one+0x324/0x500 [mlx4_core]
Caller[00000000104c613c]: mlx4_init_one+0xbc/0x120 [mlx4_core]
Caller[0000000000725f14]: local_pci_probe+0x34/0xa0
Caller[0000000000726028]: pci_call_probe+0xa8/0xe0
Caller[0000000000726310]: pci_device_probe+0x50/0x80
Caller[000000000079f700]: really_probe+0x140/0x420
Caller[000000000079fa24]: driver_probe_device+0x44/0xa0
Caller[000000000079fb5c]: __device_attach+0x3c/0x60
Caller[000000000079d85c]: bus_for_each_drv+0x5c/0xa0
Caller[000000000079f588]: device_attach+0x88/0xc0
Caller[000000000071acd0]: pci_bus_add_device+0x30/0x80
Caller[0000000000736090]: virtfn_add.clone.1+0x210/0x360
Caller[00000000007364a4]: sriov_enable+0x2c4/0x520
Caller[000000000073672c]: pci_enable_sriov+0x2c/0x40
Caller[00000000104c2d58]: mlx4_enable_sriov+0xf8/0x180 [mlx4_core]
Caller[00000000104c49ac]: mlx4_load_one+0x42c/0xd40 [mlx4_core]
Caller[00000000104c5f90]: __mlx4_init_one+0x410/0x500 [mlx4_core]
Caller[00000000104c613c]: mlx4_init_one+0xbc/0x120 [mlx4_core]
Caller[0000000000725f14]: local_pci_probe+0x34/0xa0
Caller[0000000000726028]: pci_call_probe+0xa8/0xe0
Caller[0000000000726310]: pci_device_probe+0x50/0x80
Caller[000000000079f700]: really_probe+0x140/0x420
Caller[000000000079fa24]: driver_probe_device+0x44/0xa0
Caller[000000000079fb08]: __driver_attach+0x88/0xa0
Caller[000000000079d90c]: bus_for_each_dev+0x6c/0xa0
Caller[000000000079f29c]: driver_attach+0x1c/0x40
Caller[000000000079e35c]: bus_add_driver+0x17c/0x220
Caller[00000000007a02d4]: driver_register+0x74/0x120
Caller[00000000007263fc]: __pci_register_driver+0x3c/0x60
Caller[00000000104f62bc]: mlx4_init+0x60/0xcc [mlx4_core]
Kernel panic - not syncing: Fatal exception
Press Stop-A (L1-A) to return to the boot prom
---[ end Kernel panic - not syncing: Fatal exception

Details:
Here is the call sequence
virtfn_add->__mlx4_init_one->dma_set_mask->dma_supported

The panic happened at line 760(file arch/sparc/kernel/iommu.c)

758 int dma_supported(struct device *dev, u64 device_mask)
759 {
760         struct iommu *iommu = dev->archdata.iommu;
761         u64 dma_addr_mask = iommu->dma_addr_mask;
762
763         if (device_mask >= (1UL << 32UL))
764                 return 0;
765
766         if ((device_mask & dma_addr_mask) == dma_addr_mask)
767                 return 1;
768
769 #ifdef CONFIG_PCI
770         if (dev_is_pci(dev))
771		return pci64_dma_supported(to_pci_dev(dev), device_mask);
772 #endif
773
774         return 0;
775 }
776 EXPORT_SYMBOL(dma_supported);

Same panic happened with Intel ixgbe driver also.

SR-IOV code looks for arch specific data while enabling
VFs. When VF device is added, driver probe function makes set
of calls to initialize the pci device. Because the VF device is
added different way than the normal PF device(which happens via
of_create_pci_dev for sparc), some of the arch specific initialization
does not happen for VF device.  That causes panic when archdata is
accessed.

To fix this, I have used already defined weak function
pcibios_setup_device to copy archdata from PF to VF.
Also verified the fix.

Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@xxxxxxxxxx>
Reviewed-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
---
v2:
 Removed RFC.
 Made changes per comments from Ethan Zhao.
 Now the changes are only in Sparc specific code.
 Removed the changes from driver/pci.
 Implemented already defined weak function pcibios_add_device
 in arch/sparc/kernel/pci.c to initialize sriov archdata. 

v3:
 Fixed the compile error reported in kbuild test robot.

 arch/sparc/kernel/pci.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index badf095..00a99c5 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -994,6 +994,23 @@ void pcibios_set_master(struct pci_dev *dev)
 	/* No special bus mastering setup handling */
 }
 
+#ifdef CONFIG_PCI_IOV
+int pcibios_add_device(struct pci_dev *dev)
+{
+	struct pci_dev *pdev;
+	/*
+	 * Add sriov arch specific initialization here.
+	 * Copy dev_archdata from PF to VF
+	 */
+	if (dev->is_virtfn) {
+		pdev = dev->physfn;
+		memcpy(&dev->dev.archdata, &pdev->dev.archdata,
+				sizeof(struct dev_archdata));
+	}
+	return 0;
+}
+#endif /* CONFIG_PCI_IOV */
+
 static int __init pcibios_init(void)
 {
 	pci_dfl_cache_line_size = 64 >> 2;
-- 
1.7.1