Re: [PATCH v6 0/3] Introduce Notify VM exit

[Chenyi Qiang]

On 5/24/2022 3:30 AM, Paolo Bonzini wrote:
> On 4/21/22 09:29, Chenyi Qiang wrote:
> > Virtual machines can exploit Intel ISA characterstics to cause
> > functional denial of service to the VMM. This series introduces a new
> > feature named Notify VM exit, which can help mitigate such kind of
> > attacks.
> >
> > Patch 1: An extension of KVM_SET_VCPU_EVENTS ioctl to inject a
> > synthesized shutdown event from user space. This is also a fix for other
> > synthesized triple fault, e.g. the RSM patch or nested_vmx_abort(),
> > which could get lost when exit to userspace to do migrate.
> >
> > Patch 2: A selftest about get/set triple fault event.
> >
> > Patch 3: The main patch to enable Notify VM exit.
>
> Chenyi, can you send v7 for inclusion?
>
> Paolo

Hi Paolo

v7 is sent out at
https://lore.kernel.org/lkml/20220524135624.22988-1-chenyi.qiang@xxxxxxxxx/

> > ---
> > Change logs:
> > v5 -> v6
> > - Do some changes in document.
> > - Add a selftest about get/set triple fault event. (Sean)
> > - extend the argument to include both the notify window and some flags
> >    when enabling KVM_CAP_X86_BUS_LOCK_EXIT CAP. (Sean)
> > - Change to use KVM_VCPUEVENT_VALID_TRIPE_FAULT in flags field and add
> >    pending_triple_fault field in struct kvm_vcpu_events, which allows
> >    userspace to make/clear triple fault request. (Sean)
> > - Add a flag in kvm_x86_ops to avoid the kvm_has_notify_vmexit global
> >    varialbe and its export.(Sean)
> > - v5: 
> > https://lore.kernel.org/lkml/20220318074955.22428-1-chenyi.qiang@xxxxxxxxx/ 
> >
> >
> > v4 -> v5
> > - rename KVM_VCPUEVENTS_SHUTDOWN to KVM_VCPUEVENTS_TRIPLE_FAULT. Make it
> >    bidirection and add it to get_vcpu_events. (Sean)
> > - v4: 
> > https://lore.kernel.org/all/20220310084001.10235-1-chenyi.qiang@xxxxxxxxx/ 
> >
> >
> > v3 -> v4
> > - Change this feature to per-VM scope. (Jim)
> > - Once VM_CONTEXT_INVALID set in exit_qualification, exit to user space
> >    notify this fatal case, especially the notify VM exit happens in L2.
> >    (Jim)
> > - extend KVM_SET_VCPU_EVENTS to allow user space to inject a shutdown
> >    event. (Jim)
> > - A minor code changes.
> > - Add document for the new KVM capability.
> > - v3: 
> > https://lore.kernel.org/lkml/20220223062412.22334-1-chenyi.qiang@xxxxxxxxx/ 
> >
> >
> > v2 -> v3
> > - add a vcpu state notify_window_exits to record the number of
> >    occurence as well as a pr_warn output. (Sean)
> > - Add the handling in nested VM to prevent L1 bypassing the restriction
> >    through launching a L2. (Sean)
> > - Only kill L2 when L2 VM is context invalid, synthesize a
> >    EXIT_REASON_TRIPLE_FAULT to L1 (Sean)
> > - To ease the current implementation, make module parameter
> >    notify_window read-only. (Sean)
> > - Disable notify window exit by default.
> > - v2: 
> > https://lore.kernel.org/lkml/20210525051204.1480610-1-tao3.xu@xxxxxxxxx/
> >
> > v1 -> v2
> > - Default set notify window to 0, less than 0 to disable.
> > - Add more description in commit message.
> > ---
> >
> > Chenyi Qiang (2):
> >    KVM: X86: Save&restore the triple fault request
> >    KVM: selftests: Add a test to get/set triple fault event
> >
> > Tao Xu (1):
> >    KVM: VMX: Enable Notify VM exit
> >
> >   Documentation/virt/kvm/api.rst                | 55 +++++++++++
> >   arch/x86/include/asm/kvm_host.h               |  9 ++
> >   arch/x86/include/asm/vmx.h                    |  7 ++
> >   arch/x86/include/asm/vmxfeatures.h            |  1 +
> >   arch/x86/include/uapi/asm/kvm.h               |  4 +-
> >   arch/x86/include/uapi/asm/vmx.h               |  4 +-
> >   arch/x86/kvm/vmx/capabilities.h               |  6 ++
> >   arch/x86/kvm/vmx/nested.c                     |  8 ++
> >   arch/x86/kvm/vmx/vmx.c                        | 48 +++++++++-
> >   arch/x86/kvm/x86.c                            | 33 ++++++-
> >   arch/x86/kvm/x86.h                            |  5 +
> >   include/uapi/linux/kvm.h                      | 10 ++
> >   tools/testing/selftests/kvm/.gitignore        |  1 +
> >   tools/testing/selftests/kvm/Makefile          |  1 +
> >   .../kvm/x86_64/triple_fault_event_test.c      | 96 +++++++++++++++++++
> >   15 files changed, 280 insertions(+), 8 deletions(-)
> >   create mode 100644 
> > tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c