linux-kernel - Re: [PATCH RESEND 00/30] My patch queue

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Date:   Tue, 08 Feb 2022 14:45:19 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Cc:     Tony Luck <tony.luck@...el.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Wanpeng Li <wanpengli@...cent.com>,
        Ingo Molnar <mingo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        intel-gvt-dev@...ts.freedesktop.org,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <seanjc@...gle.com>,
        David Airlie <airlied@...ux.ie>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
        Daniel Vetter <daniel@...ll.ch>,
        Borislav Petkov <bp@...en8.de>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>
Subject: Re: [PATCH RESEND 00/30] My patch queue

On Tue, 2022-02-08 at 13:02 +0100, Paolo Bonzini wrote:
> On 2/7/22 16:54, Maxim Levitsky wrote:
> > This is set of various patches that are stuck in my patch queue.
> > 
> > KVM_REQ_GET_NESTED_STATE_PAGES patch is mostly RFC, but it does seem
> > to work for me.
> > 
> > Read-only APIC ID is also somewhat RFC.
> > 
> > Some of these patches are preparation for support for nested AVIC
> > which I almost done developing, and will start testing very soon.
> > 
> > Resend with cleaned up CCs.
> 
> 1-9 are all bugfixes and pretty small, so I queued them.
> 
> 10 is also a bugfix but I think it should be split up further, so I'll 
> resend it.

> 
> For 11-30 I'll start reviewing them, but most of them are independent 
> series.

Thank you very much!

I must again say sorry that I posted the whole thing as a one patch series,
next time I'll post each series separately, and I also try to post
the patches as soon as I write them.

 I didn't post them because I felt that the whole thing needs good testing 
and I only recently gotten to somewhat automate my nested migration tests 
which I usually use to test this kind of work.

Best regards,
	Maxim Levitsky

PS: the strict_mmu option does have quite an effect on nested migration with npt=0/ept=0.
In my testing such migration crashes with pagefault in L2 kernel after around 50-100
iterations, while with this options, on survived ~1000 iterations and around the same on intel,
and on both machines L1 eventually crashed with a page fault instead.

Could be that it just throws timing off, or maybe we still do have some form of bug
in shadow paging after all, maybe even 2 bugs.
Hmmm....

I automated these tests so I can run them for days until I have more confidence
in what is going on.

Best regards,
	Maxim Levitsky

> 
> Paolo
>