On Tue, Apr 17, 2012 at 08:04:16AM +0200, Gerhard Wiesinger wrote: > On 15.04.2012 11:44, Avi Kivity wrote: > >On 04/12/2012 09:32 PM, Gerhard Wiesinger wrote: > >>Hello, > >> > >>I'm having problems with recents kernels and qemu-kvm with a DOS VM: > >>TD286 > >>System: Bad selector: 0007 > >>System: Bad selector: 0D87 > >>System: Bad selector: 001F > >>System: Bad selector: 0007 > >>GP at 0020 21D4 EC 0DC4 > >>Error 269 loading D:\BP\BIN\TD286.EXE into extended memory > >> > >>Another 286 DOS Extender application also rises a general protection > >>fault: > >>GP at 0020 18A1 CODE 357C > >> > >>Doesn't depend on the used DOS memory manager and is always > >>reproduceable. > >> > >>Depends only on kernel version and not qemu-kvm and seabios (tried to > >>bisect it without success): > >># NOK: Linux 3.3.1-3.fc16.x86_64 #1 SMP Wed Apr 4 18:08:51 UTC 2012 > >>x86_64 x86_64 x86_64 GNU/Linux > >># NOK: Linux 3.2.10-3.fc16.x86_64 #1 SMP Thu Mar 15 19:39:46 UTC 2012 > >>x86_64 x86_64 x86_64 GNU/Linux > >># OK: Linux 3.1.9-1.fc16.x86_64 #1 SMP Fri Jan 13 16:37:42 UTC 2012 > >>x86_64 x86_64 x86_64 GNU/Linux > >># OK: Linux 2.6.41.9-1.fc15.x86_64 #1 SMP Fri Jan 13 16:46:51 UTC 2012 > >>x86_64 x86_64 x86_64 GNU/Linux > >> > >>CPU is an AMD one. > >> > >>Any ideas how to fix it again? > >>Any switches which might help? > >> > > > >The trigger is probably > > > >>commit f1c1da2bde712812a3e0f9a7a7ebe7a916a4b5f4 > >>Author: Jan Kiszka<jan.kiszka@xxxxxxxxxxx> > >>Date: Tue Oct 18 18:23:11 2011 +0200 > >> > >> KVM: SVM: Keep intercepting task switching with NPT enabled > >> > >> AMD processors apparently have a bug in the hardware task switching > >> support when NPT is enabled. If the task switch triggers a NPF, we can > >> get wrong EXITINTINFO along with that fault. On resume, spurious > >> exceptions may then be injected into the guest. > >> > >> We were able to reproduce this bug when our guest triggered #SS > >>and the > >> handler were supposed to run over a separate task with not yet touched > >> stack pages. > >> > >> Work around the issue by continuing to emulate task switches even in > >> NPT mode. > >> > >> Signed-off-by: Jan Kiszka<jan.kiszka@xxxxxxxxxxx> > >> Signed-off-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx> > >Although it's not the patch's direct fault - it simply exposed an > >existing bug in kvm. > > > >Things to try: > >- revert the patch with a newer kernel > >- try 3.4-rc2 which has some task switch fixes from Kevin; if you want a > >Fedora kernel, use rawhide's [2] > >- post traces [1] > > > >Jan, Joerg, was an AMD erratum published for the bug? > > > >[1] http://www.linux-kvm.org/page/Tracing > >[2] > >http://mirrors.kernel.org/fedora/development/rawhide/x86_64/os/Packages/k/kernel-3.4.0-0.rc2.git2.1.fc18.x86_64.rpm > > > > Hello Avi, > > Status is as follows: > 1.) Kernel 3.4.x DIDN'T fix the problem > 2.) Reverting f1c1da2bde712812a3e0f9a7a7ebe7a916a4b5f4 FIXED the problem. > > So the bug is still in 3.2., 3.3, 3.4rc present and a possible fix > doesn't work. Should be fixed in 3.4 release. > > How to proceed further? > Can you post image of your VM somewhere? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
