On Thu, Aug 03, 2017 at 01:48:51AM +0300, Alexander Bezzubikov wrote: > 2017-08-03 1:35 GMT+03:00 Bjorn Helgaas <helgaas@xxxxxxxxxx>: > > On Tue, Jul 18, 2017 at 05:12:25PM +0300, Aleksandr Bezzubikov wrote: > >> An MSI-based SHPC built in PCI bridges can configure hotplugged devices > >> only if they notify the bridge with MSI. > > > > I think you're referring to the events listed in SHPC r1.0, sec 4.7.3, > > table 4-24, right? Attention Button Press, Isolated Power Fault, Card > > Presence Change, MRS Sensor Change, etc? > > > > So IIUC, this is really about the bridge itself generating MSIs about > > slot-related events, not the hot-added devices generating MSIs. > > > > You're right, it's definitely about the bridge's built-in SHPC > that generates MSIs. Great, thanks for confirming that. I applied this to pci/hotplug for v4.14 with the following changelog: PCI: shpchp: Enable bridge bus mastering if MSI is enabled An SHPC may generate MSIs to notify software about slot or controller events (SHPC spec r1.0, sec 4.7). A PCI device can only generate an MSI if it has bus mastering enabled. Enable bus mastering if the bridge contains an SHPC that uses MSI for event notifications. Signed-off-by: Aleksandr Bezzubikov <zuban32s@xxxxxxxxx> [bhelgaas: changelog] Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Reviewed-by: Marcel Apfelbaum <marcel@xxxxxxxxxx> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx
