diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/pci/pci.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b2879a6be..8cc6a8913 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3769,8 +3769,21 @@ int pci_enable_atomic_ops_to_root(struct pci_dev *dev, u32 cap_mask) } root = pcie_find_root_port(dev); - if (!root) + if (!root) { + + /* + * A hypervisor may expose a topology with the root port + * not visible to the guest. If the hypervisor has already + * set AtomicOp Requester Enable in the endpoint, we assume + * it has verified support in the root port, so it is safe + * for the driver to use AtomicOps. + */ + pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl2); + if (ctl2 & PCI_EXP_DEVCTL2_ATOMIC_REQ) + return 0; + return -EINVAL; + } pcie_capability_read_dword(root, PCI_EXP_DEVCAP2, &cap); if ((cap & cap_mask) != cap_mask) |