task #29600094

commit b4f6dcb9d35688392d668c46e834f72c55900b49 upstream.
Backport summary: for 4.19 kernel ICX PCIe Gen4 support.

As per Figure 6-3 in PCIe r4.0, sec 6.2.6, ERR_ messages will be forwarded
from the secondary interface to the primary interface, if the SERR# Enable
bit in the Bridge Control register is set.

It seems clear that an ACPI hotplug parameter method (_HPP or _HPX) that
tells us to "enable SERR in the command register" (ACPI v6.2, sec 6.2.8,
6.2.9.1) refers to PCI_COMMAND_SERR, which enables reporting of errors by
the function itself.

For bridges, we also interpreted that to mean we should enable
PCI_BRIDGE_CTL_SERR, which enables *forwarding* of errors by the bridge.
But we didn't enable PCI_BRIDGE_CTL_SERR anywhere else, which means we
never enabled it for non-ACPI systems or ACPI systems that didn't supply
hotplug parameters.

That means errors reported below bridges were often never forwarded up to a
Root Port where they could be signaled via AER.

Enable PCI_BRIDGE_CTL_SERR for all bridges so we can get better error
reporting for downstream devices.
Signed-off-by: NBharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
[bhelgaas: changelog]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
(cherry picked from commit b4f6dcb9d35688392d668c46e834f72c55900b49)
Signed-off-by: NEthan Zhao <haifeng.zhao@intel.com>
Signed-off-by: NArtie Ding <artie.ding@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>