Gleb Natapov wrote: > On Wed, Apr 14, 2010 at 04:12:46PM +0200, Jan Kiszka wrote: >> Gleb, you might want to have a look at this test. When using it with my >> 2.6.34 queue (or below or with QEMU), I get the following, expected >> output: >> >> fault at 8:4002ef, prev task 18, error code 1234 >> post fault >> >> When using it with master + my error-code patch, I get this: >> >> fault at 8:4002ef, prev task 18, error code 1234 >> >> post fault >> >> I.e. there is blank line, a repeated 0x0a character after returning from >> the fault handler. I'm suspecting that IO string rework triggers this. >> Instrumentation of the testdev showed that the spurious puts() was >> emitted over the instruction that the fault handler returns to. Any >> ideas? >> > Yes, handle_task_switch() needlessly exits to userspace without setting > exit reason, so last exit reason is reused (in your test case this is io write). > This patch should fix the problem: > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index bffd049..d080840 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4740,7 +4740,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason) > if (ret == X86EMUL_CONTINUE) > kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags); > > - return (ret != X86EMUL_CONTINUE); > + return (ret == X86EMUL_CONTINUE); > } > EXPORT_SYMBOL_GPL(kvm_task_switch); > Yep, makes sense and works for me as well. Jan
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