Re: [Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-31 Thread Jan Beulich
>>> On 30.03.17 at 19:09, wrote: > If you do have an external debugger attached, you don't need embedded > int3's to start with, and you'd still hit the debugger_trap_*() calls > before dying. Well, my experience (on other OSes with a better debugger) is different - there are occasions where it i

Re: [Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-30 Thread Andrew Cooper
On 30/03/17 13:08, Jan Beulich wrote: On 30.03.17 at 13:56, wrote: >> On 20/03/17 11:50, Jan Beulich wrote: >> On 20.03.17 at 11:58, wrote: ...rather than leaving fragments of old instructions in place. This reduces the chances of something going further-wrong (as the de

Re: [Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-30 Thread Jan Beulich
>>> On 30.03.17 at 13:56, wrote: > On 20/03/17 11:50, Jan Beulich wrote: > On 20.03.17 at 11:58, wrote: >>> ...rather than leaving fragments of old instructions in place. This reduces >>> the chances of something going further-wrong (as the debug trap will be >>> caught >>> and terminate th

Re: [Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-30 Thread Andrew Cooper
On 20/03/17 11:50, Jan Beulich wrote: On 20.03.17 at 11:58, wrote: >> ...rather than leaving fragments of old instructions in place. This reduces >> the chances of something going further-wrong (as the debug trap will be >> caught >> and terminate the guest) in a cascade-failure where we en

Re: [Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-20 Thread Jan Beulich
>>> On 20.03.17 at 11:58, wrote: > ...rather than leaving fragments of old instructions in place. This reduces > the chances of something going further-wrong (as the debug trap will be > caught > and terminate the guest) in a cascade-failure where we end up executing the > instruction fragments.

[Xen-devel] [PATCH v2] x86/emul: Poision the stubs with debug traps

2017-03-20 Thread Andrew Cooper
...rather than leaving fragments of old instructions in place. This reduces the chances of something going further-wrong (as the debug trap will be caught and terminate the guest) in a cascade-failure where we end up executing the instruction fragments. Before: (XEN) d2v0 exception 6 (ec=