Re: [V2 PATCH 0/6] KVM: selftests: selftests for fd-based private memory

[Ackerley Tng]

Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx> writes:

> On Fri, Feb 10, 2023 at 11:59:23AM -0800, Vishal Annapurve wrote:
> > On Tue, Jan 17, 2023 at 7:11 PM Vishal Annapurve <vannapurve@xxxxxxxxxx>  
> > wrote:
> > >
> > > ...

> > > > Last question, do you have a list of testcases that you  
> > consider "required" for
> > > > UPM?  My off-the-cuff list of selftests I want to have before  
> > merging UPM is pretty
> > > > short at this point:
> > > >
> > > >   - Negative testing of the memslot changes, e.g. bad alignment, bad  
> > fd,
> > > >     illegal memslot updates, etc.
> > > >   - Negative testing of restrictedmem, e.g. various combinations of  
> > overlapping
> > > >     bindings of a single restrictedmem instance.
> > > >   - Access vs. conversion stress, e.g. accessing a region in the  
> > guest while it's
> > > >     concurrently converted by the host, maybe with fancy guest code  
> > to try and
> > > >     detect TLB or ordering bugs?
> > >
> > > List of testcases that I was tracking (covered by the current
> > > selftests) as required:
> > > 1) Ensure private memory contents are not accessible to host userspace
> > > using the HVA
> > > 2) Ensure shared memory contents are visible/accessible from both host
> > > userspace and the guest
> > > 3) Ensure 1 and 2 holds across explicit memory conversions
> > > 4) Exercise memory conversions with mixed shared/private memory pages
> > > in a huge page to catch issues like [2]
> > > 5) Ensure that explicit memory conversions don't affect nearby GPA  
> > ranges
> > >
> > > Test Cases that will be covered by TDX/SNP selftests (in addition to
> > > above scenarios):
> > > 6) Ensure 1 and 2 holds across implicit memory conversions
> > > 7) Ensure that implicit memory conversions don't affect nearby GPA  
> > ranges
> > >
> > > Additional testcases possible:
> > > 8) Running conversion tests for non-overlapping GPA ranges of
> > > same/different memslots from multiple vcpus
> > >
> > > [1] -  
> > https://github.com/sean-jc/linux/commit/7e536bf3c45c623425bc84e8a96634efc3a619ed
> > > [2] -  
> > https://lore.kernel.org/linux-mm/CAGtprH82H_fjtRbL0KUxOkgOk4pgbaEbAydDYfZ0qxz41JCnAQ@xxxxxxxxxxxxxx/

> > List of additional testcases that could help increase basic coverage
> > (including what sean mentioned earlier):
> > 1) restrictedmem functionality testing
> >      - read/write/mmap should not work
> >      - fstat/fallocate should work as expected
> > 2) restrictedmem registration/modification testing with:
> >      - bad alignment, bad fd, modifying properties of existing memslot
> >      - Installing multiple memslots with ranges within the same
> > restricted mem files
> >      - deleting memslots with restricted memfd while guests are being  
> > executed

> In case you havn't started, I will work on 1) and 2) for the following
> days. As a start, I will first add restrictedmem tests (without KVM) then
> move to new memslots related tests.

> Chao

> > 3) Runtime restricted mem testing:
> >      - Access vs conversion testing from multiple vcpus
> >      - conversion and access to non-overlapping ranges from multiple vcpus

> > Regards,
> > Vishal

Chao, I'll work on

+ Running conversion tests for non-overlapping GPA ranges of
  same/different memslots from multiple vcpus
+ Deleting memslots with restricted memfd while guests are being
  executed
+ Installing multiple memslots with ranges within the same restricted
  mem files

this week.