On 2012-04-15 11:44, Avi Kivity wrote: > 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? It wasn't an erratum but a documented feature limitation in the AMD architecture that was simply ignored by the old code. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
