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

[Jan Beulich <jbeulich@xxxxxxxx>]

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.

Jan

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