From: Jim Mattson <jmattson@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>,
Chenyi Qiang <chenyi.qiang@intel.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] KVM: VMX: Enable Notify VM exit
Date: Fri, 25 Feb 2022 10:06:48 -0800 [thread overview]
Message-ID: <CALMp9eQHKn=ApthER084vKGiQCMdVX7ztB5iLupBPdUY59WV_A@mail.gmail.com> (raw)
In-Reply-To: <7859e03f-10fa-dbc2-ed3c-5c09e62f9016@redhat.com>
On Fri, Feb 25, 2022 at 7:13 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 2/25/22 16:12, Xiaoyao Li wrote:
> >>>>
> >>>
> >>> I don't like the idea of making things up without notifying userspace
> >>> that this is fictional. How is my customer running nested VMs supposed
> >>> to know that L2 didn't actually shutdown, but L0 killed it because the
> >>> notify window was exceeded? If this information isn't reported to
> >>> userspace, I have no way of getting the information to the customer.
> >>
> >> Then, maybe a dedicated software define VM exit for it instead of
> >> reusing triple fault?
> >>
> >
> > Second thought, we can even just return Notify VM exit to L1 to tell L2
> > causes Notify VM exit, even thought Notify VM exit is not exposed to L1.
>
> That might cause NULL pointer dereferences or other nasty occurrences.
Could we synthesize a machine check? I haven't looked in detail at the
MCE MSRs, but surely there must be room in there for Intel to reserve
some encodings for synthesized machine checks.
next prev parent reply other threads:[~2022-02-25 18:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-23 6:24 [PATCH v3] KVM: VMX: Enable Notify VM exit Chenyi Qiang
2022-02-25 11:54 ` Paolo Bonzini
2022-02-25 12:46 ` Xiaoyao Li
2022-02-25 14:54 ` Jim Mattson
2022-02-25 15:04 ` Xiaoyao Li
2022-02-25 15:12 ` Xiaoyao Li
2022-02-25 15:13 ` Paolo Bonzini
2022-02-25 18:06 ` Jim Mattson [this message]
2022-02-25 18:29 ` Sean Christopherson
2022-02-25 19:15 ` Jim Mattson
2022-02-26 4:07 ` Xiaoyao Li
2022-02-26 4:25 ` Jim Mattson
2022-02-26 4:53 ` Jim Mattson
2022-02-26 6:24 ` Xiaoyao Li
2022-02-26 14:24 ` Jim Mattson
2022-02-28 7:10 ` Xiaoyao Li
2022-02-28 14:30 ` Jim Mattson
2022-03-01 1:40 ` Xiaoyao Li
2022-03-01 4:32 ` Jim Mattson
2022-03-01 5:30 ` Xiaoyao Li
2022-03-01 21:57 ` Jim Mattson
2022-03-02 2:15 ` Chenyi Qiang
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