On Tue, 2013-02-05 at 15:42 +0200, Gleb Natapov wrote: > On Tue, Feb 05, 2013 at 06:37:35AM -0700, Alex Williamson wrote: > > On Tue, 2013-02-05 at 12:05 +0000, Pandarathil, Vijaymohan R wrote: > > > > > > > -----Original Message----- > > > > From: linux-pci-owner@xxxxxxxxxxxxxxx [mailto:linux-pci- > > > > owner@xxxxxxxxxxxxxxx] On Behalf Of Gleb Natapov > > > > Sent: Tuesday, February 05, 2013 3:37 AM > > > > To: Pandarathil, Vijaymohan R > > > > Cc: Blue Swirl; Alex Williamson; Bjorn Helgaas; Ortiz, Lance E; > > > > kvm@xxxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > > > > linux-kernel@xxxxxxxxxxxxxxx > > > > Subject: Re: [PATCH v3 3/3] QEMU-AER: Qemu changes to support AER for VFIO- > > > > PCI devices > > > > > > > > On Tue, Feb 05, 2013 at 10:59:41AM +0000, Pandarathil, Vijaymohan R wrote: > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > From: Gleb Natapov [mailto:gleb@xxxxxxxxxx] > > > > > > Sent: Tuesday, February 05, 2013 1:21 AM > > > > > > To: Pandarathil, Vijaymohan R > > > > > > Cc: Blue Swirl; Alex Williamson; Bjorn Helgaas; Ortiz, Lance E; > > > > > > kvm@xxxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > > > > > > linux-kernel@xxxxxxxxxxxxxxx > > > > > > Subject: Re: [PATCH v3 3/3] QEMU-AER: Qemu changes to support AER for > > > > VFIO- > > > > > > PCI devices > > > > > > > > > > > > On Tue, Feb 05, 2013 at 09:05:19AM +0000, Pandarathil, Vijaymohan R > > > > wrote: > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > From: Gleb Natapov [mailto:gleb@xxxxxxxxxx] > > > > > > > > Sent: Tuesday, February 05, 2013 12:05 AM > > > > > > > > To: Blue Swirl > > > > > > > > Cc: Pandarathil, Vijaymohan R; Alex Williamson; Bjorn Helgaas; > > > > Ortiz, > > > > > > Lance > > > > > > > > E; kvm@xxxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; linux- > > > > > > pci@xxxxxxxxxxxxxxx; > > > > > > > > linux-kernel@xxxxxxxxxxxxxxx > > > > > > > > Subject: Re: [PATCH v3 3/3] QEMU-AER: Qemu changes to support AER > > > > for > > > > > > VFIO- > > > > > > > > PCI devices > > > > > > > > > > > > > > > > On Sun, Feb 03, 2013 at 04:36:11PM +0000, Blue Swirl wrote: > > > > > > > > > On Sun, Feb 3, 2013 at 2:10 PM, Pandarathil, Vijaymohan R > > > > > > > > > <vijaymohan.pandarathil@xxxxxx> wrote: > > > > > > > > > > - Create eventfd per vfio device assigned to a guest > > > > and > > > > > > > > register an > > > > > > > > > > event handler > > > > > > > > > > > > > > > > > > > > - This fd is passed to the vfio_pci driver through the > > > > > > SET_IRQ > > > > > > > > ioctl > > > > > > > > > > > > > > > > > > > > - When the device encounters an error, the eventfd is > > > > > > signalled > > > > > > > > > > and the qemu eventfd handler gets invoked. > > > > > > > > > > > > > > > > > > > > - In the handler decide what action to take. Current > > > > action > > > > > > > > taken > > > > > > > > > > is to terminate the guest. > > > > > > > > > > > > > > > > > > Usually this is not OK, but I guess this is not guest > > > > triggerable. > > > > > > > > > > > > > > > > > Still not OK. Why not stop a guest with appropriate stop reason? > > > > > > > > > > > > > > The thinking was that since this is a hardware error, we would want > > > > to > > > > > > stop the guest at the earliest. The hw_error() routine which aborts the > > > > > > qemu process was suggested by Alex and that seemed appropriate. Earlier > > > > I > > > > > > was using qemu_system_shutdown_request(). Any suggestions ? > > > > > > > > > > > > > I am thinking vm_stop(). Stopping SMP guest (and UP too in fact) > > > > > > involves sending IPIs to other cpus running guest's vcpus. Both exit() > > > > > > and vm_stop() will do it, but former is implicitly in the kernel and > > > > > > later is explicitly in QEMU. > > > > > > > > > > I had used vm_stop(RUN_STATE_SHUTDOWN) earlier in my code. But while > > > > testing, guest ended up in a hang rather than exiting. There seems to some > > > > cleanup work which is being done as part of vm_stop. In our case, we wanted > > > > the guest to exit immediately. So use of hw_error() seemed appropriate. > > > > > > > > > What makes you think it hang? It stopped, precisely what it should do if > > > > you call vm_stop(). Now it is possible for vm user to investigate what > > > > happened and even salvage some data from guest memory. > > > > > > That was ignorance on my part on the expected behavior of vm_stop(). > > > So what you are suggesting is to stop the guest displaying an appropriate > > > error/next-steps message and have the users do any data-collection/investigation > > > and then manually kill the guest, if they so desire. Right ? > > > > > > Sounds reasonable. As long as the guest is not touching the device, it should be okay. > > > Alex, Any comments ? > > > > What's the libvirt behavior when a guest goes to vm_stop? My only > > concern would be whether the user is going to be confused by a state > > where the vm is still up, but not running. I imagine they'll have to > > manually stop it and restart it to continue. Thanks, > > > vm_stop() is already the behaviour on KVM internal errors, so management > stack knows how to handle those. Of course vfio should use meaningful > stop reason and not just reuse existing one. Ok, sounds like a good approach to me. Thanks, Alex -- 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
