Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since race

[Paolo Bonzini]

Il 04/07/2014 13:07, Jan Kiszka ha scritto:
> On 2014-07-04 12:52, Jan Kiszka wrote:
> > On 2014-07-04 11:38, Paolo Bonzini wrote:
> > > Il 04/07/2014 11:33, Jan Kiszka ha scritto:
> > > > The compiler is not aware of the fact that push/pop exists in this
> > > > function and, thus, places the vmcs parameter on the stack without
> > > > reserving the space. So the pushfq will overwrite the vmcs pointer and
> > > > let the function fail.
> > >
> > > Is that just a missing "memory" clobber?  push/pop clobbers memory.
> >
> > Nope, we would needs some clobber like "stack". I wonder what is
> > required to use push in inline assembly safely?
>
> My colleague just found the answer: -mno-red-zone is required for 64-bit
> in order to play freely with the stack (or you need to stay off that
> zone, apparently some 128 bytes below the stack pointer). The kernel
> sets that switch, our unit tests do not.

Are you posting a patch?  (Also, what compiler is that?)

Paolo

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