Re: [Xen-devel] [PATCH V6] x86/altp2m: Hypercall to set altp2m view visibility

[Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>]

On 04.03.2020 16:07, Jan Beulich wrote:
> On 04.03.2020 14:57, Alexandru Stefan ISAILA wrote:
>> Hi George,
>>
>> This is a kind reminder if you can take a look at this patch when you
>> have the time.
> 
> Are you perhaps not aware of the recent maintainer change on
> xen/arch/x86/mm/? What you need to go hunt is ...
> 
>> On 03.03.2020 14:23, Alexandru Stefan ISAILA wrote:
>>> At this moment a guest can call vmfunc to change the altp2m view. This
>>> should be limited in order to avoid any unwanted view switch.
>>>
>>> The new xc_altp2m_set_visibility() solves this by making views invisible
>>> to vmfunc.
>>> This is done by having a separate arch.altp2m_working_eptp that is
>>> populated and made invalid in the same places as altp2m_eptp. This is
>>> written to EPTP_LIST_ADDR.
>>> The views are made in/visible by marking them with INVALID_MFN or
>>> copying them back from altp2m_eptp.
>>> To have consistency the visibility also applies to
>>> p2m_switch_domain_altp2m_by_id().
>>>
>>> Note: If altp2m mode is set to mixed the guest is able to change the view
>>> visibility and then call vmfunc.
>>>
>>> Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
>>> ---
>>> CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
>>> CC: Wei Liu <wl@xxxxxxx>
>>> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>> CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
>>> CC: Jan Beulich <jbeulich@xxxxxxxx>
>>> CC: Julien Grall <julien@xxxxxxx>
>>> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>>> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>>> CC: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
>>> CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
>>> CC: Kevin Tian <kevin.tian@xxxxxxxxx>
>>> ---
>>> Changes since V5:
>>>     - Change idx type from uint16_t to unsigned int
>>>     - Add rc var and dropped the err return from p2m_get_suppress_ve().
>>>
>>> Changes since V4:
>>>     - Move p2m specific things from hvm to p2m.c
>>>     - Add comment for altp2m_idx bounds check
>>>     - Add altp2m_list_lock/unlock().
>>>
>>> Changes since V3:
>>>     - Change var name form altp2m_idx to idx to shorten line length
>>>     - Add bounds check for idx
>>>     - Update commit message
>>>     - Add comment in xenctrl.h.
>>>
>>> Changes since V2:
>>>     - Drop hap_enabled() check
>>>     - Reduce the indentation depth in hvm.c
>>>     - Fix assignment indentation
>>>     - Drop pad2.
>>>
>>> Changes since V1:
>>>     - Drop double view from title.
>>> ---
>>>    tools/libxc/include/xenctrl.h   |  7 +++++++
>>>    tools/libxc/xc_altp2m.c         | 24 +++++++++++++++++++++++
> 
> ... a tool stack ack and ...
> 
>>>    xen/arch/x86/hvm/hvm.c          | 14 ++++++++++++++
>>>    xen/arch/x86/hvm/vmx/vmx.c      |  2 +-
> 
> ... and a VMX one, also for ...
> 
>>>    xen/arch/x86/mm/hap/hap.c       | 15 +++++++++++++++
>>>    xen/arch/x86/mm/p2m-ept.c       |  1 +
> 
> ... this.
> 

Ok, tanks for this, I just saw the changes on the maintainers.

Alex

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