Re: [Xen-devel] [RFC v2]Proposal to allow setting up shared memory areas between VMs from xl config file

[Zhongze Liu <blackskygg@xxxxxxxxx>]

Hi Julien,

2017-06-21 1:29 GMT+08:00 Julien Grall <julien.grall@xxxxxxx>:
> Hi,
>
> Thank you for the new proposal.
>
> On 06/20/2017 06:18 PM, Zhongze Liu wrote:
>>
>> In the example above. A memory area ID1 will be shared between vm1 and
>> vm2.
>> This area will be taken from vm1 and mapped into vm2's stage-2 page table.
>> The parameter "prot=RO" means that this memory area are offered with
>> read-only
>> permission. vm1 can access this area using gmfn1~gmfn2, and vm2 using
>> gmfn5~gmfn6.
>
>
> [...]
>
>>
>> ======================================
>> 2.3 mapping the memory areas
>> ======================================
>> Handle the newly added config option in tools/{xl, libxl} and utilize
>> toos/libxc to do the actual memory mapping. Specifically, we will use
>> a wrapper to XENMME_add_to_physmap_batch with XENMAPSPACE_gmfn_foreign to
>> do the actual mapping. But since there isn't such a wrapper in libxc,
>> we'll
>> have to add a new wrapper, xc_domain_add_to_physmap_batch in
>> libxc/xc_domain.c
>
>
> In the paragrah above, you suggest the user can select the permission on the
> shared page. However, the hypercall XENMEM_add_to_physmap does not currently
> take permission. So how do you plan to handle that?
>

I think this could be done via XENMEM_access_op?

Cheers,

Zhongze Liu

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