From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "David Hildenbrand" <david@redhat.com>,
"Wanpeng Li" <kernellwp@gmail.com>, kvm <kvm@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
"Mohammed Gamal" <mmorsy@redhat.com>,
"Cathy Avery" <cavery@redhat.com>, "Bandan Das" <bsd@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V
Date: Tue, 16 Jan 2018 15:43:56 +0100 [thread overview]
Message-ID: <87po69hnir.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <fce01165-912c-a592-2f10-71041ab13b29@redhat.com> (Paolo Bonzini's message of "Tue, 16 Jan 2018 15:27:33 +0100")
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 16/01/2018 14:58, Vitaly Kuznetsov wrote:
>>> Haven't looked into the details, but we have to watch out for other
>>> VCPUs trying to modify that vmcs12.
>>>
>>> Basically because other VCPUs could try to modify values in vmcs12 while
>>> we are currently building vmcs02. Nasty races could result in us copying
>>> stuff (probably unchecked) into vmcs02 and therefore running something
>>> that was not intended.
>>>
>> I don't think we share VMCS among vCPUs, do we?
>
> VMCS is just memory, so who knows what a malicious L1 guest will do.
> But for vmread/vmwrite we can go through hypervisor memory, for
> enlightened VMCS we cannot.
>
True; not sure if Hyper-V actually copies the data to some internal
storage, probably it does. TLFS explicitly forbids making the same
enlightened VMCS active on several vCPUs simultaneously but again, this
is just memory...
--
Vitaly
next prev parent reply other threads:[~2018-01-16 14:43 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 17:30 [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 1/6] x86/kvm: rename HV_X64_MSR_APIC_ASSIST_PAGE to HV_X64_MSR_VP_ASSIST_PAGE Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 2/6] x86/hyper-v: define virtual processor assist page structure Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 3/6] x86/hyper-v: allocate and use hv_vp_assist_pages Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 4/6] x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 5/6] x86/hyper-v: detect nested features Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 6/6] x86/kvm: use enlightened VMCS when running on Hyper-V Vitaly Kuznetsov
2018-01-16 1:21 ` [RFC 0/6] Enlightened VMCS support for KVM " Wanpeng Li
2018-01-16 12:05 ` Vitaly Kuznetsov
2018-01-16 13:39 ` David Hildenbrand
2018-01-16 13:47 ` Paolo Bonzini
2018-01-16 13:58 ` Vitaly Kuznetsov
2018-01-16 14:27 ` Paolo Bonzini
2018-01-16 14:43 ` Vitaly Kuznetsov [this message]
2018-01-16 14:56 ` David Hildenbrand
2018-01-16 15:03 ` Paolo Bonzini
2018-01-16 17:16 ` Radim Krčmář
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