Re: [PATCH v1 4/7] x86/vmx: add do_vmtrace_op

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.06.2020 13:55, Roger Pau Monné wrote:
> On Thu, Jun 18, 2020 at 01:01:39PM +0200, Michał Leszczyński wrote:
>> It was previously stated that:
>>
>>> PVH or HVM domain
>>> won't be able to use this interface since it has no way to request the
>>> mapping of a specific mfn into it's physmap.
>>
>> but however, taking LibVMI as an example:
>>
>> https://github.com/libvmi/libvmi/blob/c461e20ae88bc62c08c27f50fcead23c27a30f9e/libvmi/driver/xen/xen.c#L51
>>
>> An essential abstraction xen_get_memory() relies on xc_map_foreign_range(). 
>> Doesn't this mean that it's not usable from PVH or HVM domains, or did I got 
>> it all wrong?
> 
> That was my fault, so the buffer mfns are assigned to Xen, and then
> the Xen domain ID is used to map those, which should work on both PV
> and HVM (or PVH).
> 
> I still think using XENMEM_acquire_resource might be better, but I
> would let others comment.

+1

Jan