On Sat, Jun 28, 2014 at 01:44:31PM +0200, Borislav Petkov wrote: > qemu-system-x86-20240 [006] ...1 9406.484134: kvm_page_fault: address 7fffb62ba318 error_code 2 > qemu-system-x86-20240 [006] ...1 9406.484136: kvm_inj_exception: #PF (0x2)a > > kvm injects the #PF into the guest. > > qemu-system-x86-20240 [006] d..2 9406.484136: kvm_entry: vcpu 1 > qemu-system-x86-20240 [006] d..2 9406.484137: kvm_exit: reason PF excp rip 0xffffffff8161130f info 2 7fffb62ba318 > qemu-system-x86-20240 [006] ...1 9406.484138: kvm_page_fault: address 7fffb62ba318 error_code 2 > qemu-system-x86-20240 [006] ...1 9406.484141: kvm_inj_exception: #DF (0x0) > > Second #PF at the same address and kvm injects the #DF. > > BUT(!), why? > > I probably am missing something but WTH are we pagefaulting at a > user address in context_switch() while doing a lockdep call, i.e. > spin_release? We're not touching any userspace gunk there AFAICT. > > Is this an async pagefault or so which kvm is doing so that the guest > rip is actually pointing at the wrong place? > There is nothing in the trace that point to async pagefault as far as I see. > Or something else I'm missing, most probably... > Strange indeed. Can you also enable kvmmmu tracing? You can also instrument kvm_multiple_exception() to see which two exception are combined into #DF. -- 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
