Re: [Xen-devel] [PATCH for-4.12 V5 2/2] x86/altp2m: fix HVMOP_altp2m_set_domain_state race

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 2/18/19 1:19 PM, Jan Beulich wrote:
> > > > On 15.02.19 at 16:41, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> > HVMOP_altp2m_set_domain_state does not domain_pause(), presumably
> > on purpose (as it was originally supposed to cater to a in-guest
> > agent, and a domain pausing itself is not a good idea).
> >
> > This can lead to domain crashes in the vmx_vmexit_handler() code
> > that checks if the guest has the ability to switch EPTP without an
> > exit. That code can __vmread() the host p2m's EPT_POINTER
> > (before HVMOP_altp2m_set_domain_state "for_each_vcpu()" has a
> > chance to run altp2m_vcpu_initialise(), but after
> > d->arch.altp2m_active is set).
> >
> > Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> Also I assume you mean to have the same justification here as
> you have in patch 1, as to 4.12 inclusion. And for this reason
> I'm also Cc-ing Jürgen again.
Ideed, I do. Thank you very much.


Thanks,
Razvan

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