Re: [Xen-devel] [PATCH v6] altp2m: Introduce external-only and limited use-cases

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.04.17 at 17:24, <tamas.lengyel@xxxxxxxxxxxx> wrote:
> Currently setting altp2mhvm=1 in the domain configuration allows access to the
> altp2m interface for both in-guest and external privileged tools. This poses
> a problem for use-cases where only external access should be allowed, 
> requiring
> the user to compile Xen with XSM enabled to be able to appropriately restrict
> access.
> 
> In this patch we deprecate the altp2mhvm domain configuration option and
> introduce the altp2m option, which allows specifying if by default the altp2m
> interface should be external-only or limited. The information is stored in
> HVM_PARAM_ALTP2M which we now define with specific XEN_ALTP2M_* modes.
> If external mode is selected, the XSM check is shifted to use XSM_DM_PRIV
> type check, thus restricting access to the interface by the guest itself. Note
> that we keep the default XSM policy untouched. Users of XSM who wish to 
> enforce
> external mode for altp2m can do so by adjusting their XSM policy directly,
> as this domain config option does not override an active XSM policy.
> 
> Also, as part of this patch we adjust the hvmop handler to require
> HVM_PARAM_ALTP2M to be of a type other then disabled for all ops. This has 
> been
> previously only required for get/set altp2m domain state, all other options
> were gated on altp2m_enabled. Since altp2m_enabled only gets set during set
> altp2m domain state, this change introduces no new requirements to the other
> ops but makes it more clear that it is required for all ops.
> 
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
> Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

x86 hypervisor and public interface parts
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>



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