Re: [Xen-devel] [PATCH V4] x86/altp2m: Fix crash with INVALID_ALTP2M EPTP index

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.06.18 at 15:12, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> xc_altp2m_set_vcpu_enable_notify() ends up calling
> altp2m_vcpu_update_vmfunc_ve(), which sets the
> SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS bit on
> vmx_secondary_exec_control. A subsequent call to
> xc_altp2m_set_domain_state(..., false) (i.e. disabling altp2m
> for the domain) ends up calling altp2m_vcpu_destroy(), which
> calls (in this order) altp2m_vcpu_reset() (which sets the
> current EPTP index to INVALID_ALTP2M), altp2m_vcpu_update_p2m()
> (which __vmwrite()s EPTP_INDEX as INVALID_ALTP2M if
> SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS is set), and
> altp2m_vcpu_update_vmfunc_ve() (which finally clears
> SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS).

I continue to consider this paragraph unreadable, but perhaps it's
just me. The rest of the description looks reasonable to me now.

Please allow some more time than a single day between versions
though, so others also have a chance to respond.

Jan




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