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PCI: Do not enable AtomicOps on VFs
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Host crashes when pci_enable_atomic_ops_to_root() is called for VFs with
virtual buses. The virtual buses added to SR-IOV have bus->self set to NULL
and host crashes due to this.

  PID: 4481   TASK: ffff89c6941b0000  CPU: 53  COMMAND: "bash"
  ...
   #3 [ffff9a9481713808] oops_end at ffffffffb9025cd6
   #4 [ffff9a9481713828] page_fault_oops at ffffffffb906e417
   #5 [ffff9a9481713888] exc_page_fault at ffffffffb9a0ad14
   #6 [ffff9a94817138b0] asm_exc_page_fault at ffffffffb9c00ace
      [exception RIP: pcie_capability_read_dword+28]
      RIP: ffffffffb952fd5c  RSP: ffff9a9481713960  RFLAGS: 00010246
      RAX: 0000000000000001  RBX: ffff89c6b1096000  RCX: 0000000000000000
      RDX: ffff9a9481713990  RSI: 0000000000000024  RDI: 0000000000000000
      RBP: 0000000000000080   R8: 0000000000000008   R9: ffff89c64341a2f8
      R10: 0000000000000002  R11: 0000000000000000  R12: ffff89c648bab000
      R13: 0000000000000000  R14: 0000000000000000  R15: ffff89c648bab0c8
      ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
   #7 [ffff9a9481713988] pci_enable_atomic_ops_to_root at ffffffffb95359a6
   #8 [ffff9a94817139c0] bnxt_qplib_determine_atomics at ffffffffc08c1a33 [bnxt_re]
   grate-driver#9 [ffff9a94817139d0] bnxt_re_dev_init at ffffffffc08ba2d1 [bnxt_re]

Per PCIe r5.0, sec 9.3.5.10, the AtomicOp Requester Enable bit in Device
Control 2 is reserved for VFs.  The PF value applies to all associated VFs.

Return -EINVAL if pci_enable_atomic_ops_to_root() is called for a VF.

Link: https://lore.kernel.org/r/[email protected]
Fixes: 35f5ace ("RDMA/bnxt_re: Enable global atomic ops if platform supports")
Fixes: 430a236 ("PCI: Add pci_enable_atomic_ops_to_root()")
Signed-off-by: Selvin Xavier <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Andy Gospodarek <[email protected]>
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selvintxavier authored and bjorn-helgaas committed Nov 4, 2021
1 parent 06dc660 commit 5ec0a6f
Showing 1 changed file with 8 additions and 0 deletions.
8 changes: 8 additions & 0 deletions drivers/pci/pci.c
Original file line number Diff line number Diff line change
Expand Up @@ -3719,6 +3719,14 @@ int pci_enable_atomic_ops_to_root(struct pci_dev *dev, u32 cap_mask)
struct pci_dev *bridge;
u32 cap, ctl2;

/*
* Per PCIe r5.0, sec 9.3.5.10, the AtomicOp Requester Enable bit
* in Device Control 2 is reserved in VFs and the PF value applies
* to all associated VFs.
*/
if (dev->is_virtfn)
return -EINVAL;

if (!pci_is_pcie(dev))
return -EINVAL;

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