On Fri, Jan 29, 2016 at 09:53:08AM -0800, Ray Jui wrote: > On 1/29/2016 9:30 AM, Bjorn Helgaas wrote: > >It looks somewhat > >hacky to have the PAXC-specific "slot > 0" test, and I'm not sure it > >should be necessary (again, unless there's some implementation > >deficiency in that PAXC embedded endpoint). I'm looking at section > >7.3 in the spec, and it seems like that endpoint *should* handle > >a config transaction with a non-zero Device Number, i.e., "slot", as > >an Unsupported Request. This should be standard behavior for all PCIe > >endpoints -- we can generate config transactions like that on all root > >complexes on all systems, so all endpoints should be able to handle > >it. > > Unfortunately, it looks like the integrated endpoint connected to > PAXC is not fully compliant to the above described behavior. > > I tested by removing the "slot > 0" test in the driver and added > some debug prints, it appears that attempted access to slot 1, 2, 3 > cannot be rejected properly and results an kernel crash. > > Debugging prints are in the format of <bus>:<slot>:<func> offset:0x<where> > > [ 3.871332] 1:1:0 offset:0x0 > [ 3.874552] 1:2:0 offset:0x0 > [ 3.877759] 1:3:0 offset:0x0 > [ 3.881454] Bad mode in Error handler detected, code 0xbf000002 -- SError > [ 3.888996] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0+ #117 > [ 3.895801] Hardware name: Broadcom NS2 SVK (DT) > [ 3.900967] task: ffffffc0fb088000 ti: ffffffc0fb090000 task.ti: > ffffffc0fb090000 > [ 3.909271] PC is at pci_generic_config_read32+0x74/0xa0 > [ 3.915190] LR is at pci_generic_config_read32+0x28/0xa0 > [ 3.921081] pc : [<ffffffc000374684>] lr : [<ffffffc000374638>] > pstate: 200000c5 > [ 3.929309] sp : ffffffc0fb093900 > [ 3.932969] x29: ffffffc0fb093900 x28: ffffffc0fa9d2400 > [ 3.938864] x27: ffffffc07a93c090 x26: 0000000000000000 > [ 3.944838] x25: 0000000000000000 x24: ffffffc0fa9d2800 > [ 3.950776] x23: 0000000000000040 x22: ffffffc000883318 > [ 3.956678] x21: 0000000000000018 x20: ffffffc0fb093a0c > [ 3.962589] x19: 0000000000000000 x18: 000000000000073f > [ 3.968491] x17: ffffffffffffffff x16: 0000000000000011 > [ 3.974356] x15: 0000000000000000 x14: ffffffffffffffff > [ 3.980311] x13: ffffffffffffffff x12: 0000000000000000 > [ 3.986258] x11: 00000000000002eb x10: 0000000000000006 > [ 3.992177] x9 : 00000000000002ec x8 : 3078303a74657366 > [ 3.998106] x7 : ffffffc000812a70 x6 : ffffffc0007d4dc4 > [ 4.004026] x5 : 000000000000000f x4 : ffffffc0fb09398c > [ 4.009937] x3 : 0000000000000004 x2 : ffffff80000d41f8 > [ 4.015865] x1 : ffffff80000d4000 x0 : 0000000000000000 > > Therefore, we need to keep this 'hacky check' in the iProc host driver. OK, great, then we can finally put this one to bed. Thanks for checking it out! Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
