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

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Date:   Tue, 7 Mar 2023 10:18:09 +0800
From:   Chao Peng <chao.p.peng@...ux.intel.com>
To:     Ackerley Tng <ackerleytng@...gle.com>
Cc:     vannapurve@...gle.com, seanjc@...gle.com, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, pbonzini@...hat.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        joro@...tes.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
        shuah@...nel.org, yang.zhong@...el.com, ricarkol@...gle.com,
        aaronlewis@...gle.com, wei.w.wang@...el.com,
        kirill.shutemov@...ux.intel.com, corbet@....net, hughd@...gle.com,
        jlayton@...nel.org, bfields@...ldses.org,
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        maciej.szmigiero@...cle.com, mizhang@...gle.com, bgardon@...gle.com
Subject: Re: [V2 PATCH 0/6] KVM: selftests: selftests for fd-based private
 memory

On Mon, Mar 06, 2023 at 06:21:24PM +0000, Ackerley Tng wrote:
> Chao Peng <chao.p.peng@...ux.intel.com> 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@...gle.com> 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@mail.gmail.com/
> 
> > > 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.

Thanks Ackerley. Looks good to me.

BTW, for whom may have interest, below are the testcases I added:
https://github.com/chao-p/linux/commit/24dd1257d5c93acb8c8cc6c76c51cf6869970f8a
https://github.com/chao-p/linux/commit/39a872ef09d539ce0c953451152eb05276b87018
https://github.com/chao-p/linux/commit/ddd2c92b268a2fdc6158f82a6169ad1a57f2a01d

Chao