On Mon, 2020-10-12 at 17:58 -0500, Bjorn Helgaas wrote: > On Fri, Oct 09, 2020 at 11:51:39PM +0000, Kelley, Sean V wrote: > > On Fri, 2020-10-09 at 15:07 -0700, Sean V Kelley wrote: > > So I tested the following out, including your moving flr to aer.c: > > > > - Renamed flr_on_rciep() to flr_on_rc() for RC devices (RC_END and > > RC_EC) > > > > - Moved check on dev->rcec into aer_root_reset() including the FLR. > > > > - Reworked pci_walk_bridge() to drop extra dev argument and check > > locally for the bridge->rcec. Maybe should also check on type when > > checking on bridge->rcec. > > > > Note I didn't use the check on aer_cap existence because I think > > you > > had added that for simply being able to skip over for the non- > > native > > case and I handle that with the single goto at the beginning which > > takes you to the FLR. > > Right. Well, my thinking was that "root" would be a device with the > AER Root Error Command and Root Error Status registers, i.e., a Root > Port or RCEC. IIUC that basically means the APEI case where firmware > gives us an error record. Got it. > > Isn't the existing v5.9 code buggy in that it unconditionally pokes > these registers? I think the APEI path can end up here, and firmware > probably has not granted us control over AER. Yes, APEI path can end up here even in the absence of AER control. > > Somewhat related question: I'm a little skeptical about the fact that > aer_root_reset() currently does: > > - clear ROOT_PORT_INTR_ON_MESG_MASK > - do reset > - clear PCI_ERR_ROOT_STATUS > - enable ROOT_PORT_INTR_ON_MESG_MASK It's a bit of a mix and growing with RC_END handling. > > In the APEI path all this AER register manipulation must be done by > firmware before passing the error record to the OS. So in the native > case where the OS does own the AER registers, why can't the OS do > that > manipulation in the same order, i.e., all before doing the reset? And you're right, the mix here imposes additional complexity for native versus non-native. If you're not actively engaged with the code, it's not obvious. So, yes moving it out would make more sense. > > > So this is rough, compiled, tested with AER injections but that's > > it... > > I couldn't actually apply the patch below because it seems to be > whitespace-damaged, but I think I like it. Yes, it was a quick copy-paste to an existing email. Will work with your branch. > > - It would be nice to be able to just call pcie_flr() and not have > to add flr_on_rc(). I can't remember why we need the > pcie_has_flr() / pcie_flr() dance. It seems racy and ugly, but I > have a vague recollection that there actually is some reason for > it. I'll have a look. > > - I would *rather* consolidate the AER register updates and test > for > the non-native case once instead of treating it like a completely > separate path with a "goto". But maybe not possible. Not a big > deal either way. Following your line of reasoning above, I think we can better consolidate the AER register updates. > > - Getting rid of the extra "dev" argument to pci_walk_bridge() is a > great side-effect. I didn't even notice that. > > - If we can simplify that "state == pci_channel_io_frozen" case as > this does, that is a *big* deal because there are other patches > just waiting to touch that reset and it will be much simpler if > there's only one reset_subordinate_devices() call there. Agreed. > > If you do work this up, I'd really appreciate it if you can start > with > my pci/err branch so I don't have to re-do all the tweaks I've > already > done: > > > https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/err > Will do. Thanks, Sean > Bjorn
