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



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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