On Thu, Oct 17, 2019 at 07:57:35PM -0400, Derek Yerger wrote: > On 10/16/19 1:49 PM, Sean Christopherson wrote: > >On Wed, Oct 16, 2019 at 11:28:57AM -0600, Alex Williamson wrote: > >>On Wed, 16 Oct 2019 00:49:51 -0400 > >>Derek Yerger<derek@xxxxxxx> wrote: > >> > >>>In at least Linux 5.2.7 via Fedora, up to 5.2.18, guest OS applications > >>>repeatedly crash with segfaults. The problem does not occur on 5.1.16. > >>> > >>>System is running Fedora 29 with kernel 5.2.18. Guest OS is Windows 10 with an > >>>AMD Radeon 540 GPU passthrough. When on 5.2.7 or 5.2.18, specific windows > >>>applications frequently and repeatedly crash, throwing exceptions in random > >>>libraries. Going back to 5.1.16, the issue does not occur. > >>> > >>>The host system is unaffected by the regression. > >>> > >>>Keywords: kvm mmu pci passthrough vfio vfio-pci amdgpu > >>> > >>>Possibly related: Unmerged [PATCH] KVM: x86/MMU: Zap all when removing memslot > >>>if VM has assigned device > >>That was never merged because it was superseded by: > >> > >>d012a06ab1d2 Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot" > >> > >>That revert also induced this commit: > >> > >>002c5f73c508 KVM: x86/mmu: Reintroduce fast invalidate/zap for flushing memslot > >> > >>Both of these were merged to stable, showing up in 5.2.11 and 5.2.16 > >>respectively, so seeing these sorts of issues might be considered a > >>known issue on 5.2.7, but not 5.2.18 afaik. Do you have a specific > >>test that reliably reproduces the issue? Thanks, > Test case 1: Kernel 5.2.18, PCI passthrough, Windows 10 guest, error condition. > Error 1: Application error in Firefox, restarting firefox and restoring tabs > reliably causes application crash with stack overflow error. > Error 2: Guest BSOD by the morning if left idle > Error 3: Guest BSOD within 1 minute of using SolidWorks CAD software > > Test case 2: Kernel 5.2.18, no PCI passthrough, same environment. Guest BSOD > encountered. > > Test case 3: Kernel 5.1.16, no PCI passthrough, same environment. Worked in > Solidworks for 10 minutes without BSOD. Opened firefox and restored tabs, no > crash. > > Test case 4: Kernel 5.1.16, with PCI passthrough, same environment. Worked > in Solidworks for a half hour. Opened firefox and restored tabs, no crash. > > Other factors: The guest does not change between tests. Same drivers, > software, etc. I have reliably switched between 5.2.x and 5.1.x multiple > times in the past month and repeatably see issues with 5.2.x. At this point > I'm unsure if it's PCI passthrough causing the problem. > > I know I should probably start from fresh host and guest, but time isn't > really permitting. > >Also, does the failure reproduce on on 5.2.1 - 5.2.6? The memslot debacle > >exists on all flavors of 5.2.x, if the errors showed up in 5.2.7 then they > >are being caused by something else. > After experiencing the issue in absence of PCI passthrough, I believe the > problem is unrelated to the memslot debacle. Heh, should've checked from the get go... It's definitely not the memslot issue, because the memslot bug is in 5.1.16 as well. :-) > I'm stuck on 5.1.x for now, maybe I'll give up and get a dedicated windows > machine /s What hardware are you running on? I was thinking this was AMD specific, but then realized you said "AMD Radeon 540 GPU" and not "AMD CPU".
