From 5ec0a6fcb60ea430f8ee7e0bec22db9b22f856d3 Mon Sep 17 00:00:00 2001

From: Selvin Xavier <selvin.xavier@broadcom.com>

Date: Sat, 11 Sep 2021 03:03:05 -0700

Subject: PCI: Do not enable AtomicOps on VFs

Git-commit: 5ec0a6fcb60ea430f8ee7e0bec22db9b22f856d3

Patch-mainline: v5.16-rc1

References: bsc#1129770

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]

   #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/1631354585-16597-1-git-send-email-selvin.xavier@broadcom.com

Fixes: 35f5ace5dea4 ("RDMA/bnxt_re: Enable global atomic ops if platform supports")

Fixes: 430a23689dea ("PCI: Add pci_enable_atomic_ops_to_root()")

Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Reviewed-by: Andy Gospodarek <gospo@broadcom.com>

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

---

 drivers/pci/pci.c | 8 ++++++++

 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c

index c63598c1cdd85..e55d944ff30f1 100644

--- a/drivers/pci/pci.c

+++ b/drivers/pci/pci.c

@@ -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;

-- 

2.36.0