The KVM introspection subsystem provides a facility for applications running
on the host or in a separate VM, to control the execution of other VM-s
(pause, resume, shutdown), query the state of the vCPUs (GPRs, MSRs etc.),
alter the page access bits in the shadow page tables (only for the hardware
backed ones, eg. Intel's EPT) and receive notifications when events of
interest have taken place (shadow page table level faults, key MSR writes,
hypercalls etc.). Some notifications can be responded to with an action
(like preventing an MSR from being written), others are mere informative
(like breakpoint events which can be used for execution tracing).
With few exceptions, all events are optional. An application using this
subsystem will explicitly register for them.
The use case that gave way for the creation of this subsystem is to monitor
the guest OS and as such the ABI/API is highly influenced by how the guest
software (kernel, applications) sees the world. For example, some events
provide information specific for the host CPU architecture
(eg. MSR_IA32_SYSENTER_EIP) merely because its leveraged by guest software
to implement a critical feature (fast system calls).
At the moment, the target audience for KVMI are security software authors
that wish to perform forensics on newly discovered threats (exploits) or
to implement another layer of security like preventing a large set of
kernel rootkits simply by "locking" the kernel image in the shadow page
tables (ie. enforce .text r-x, .rodata rw- etc.). It's the latter case that
made KVMI a separate subsystem, even though many of these features are
available in the device manager (eg. QEMU). The ability to build a security
application that does not interfere (in terms of performance) with the
guest software asks for a specialized interface that is designed for minimum
overhead.
This patch series is based on 5.0-rc7,
commit de3ccd26fafc ("KVM: MMU: record maximum physical address width in
kvm_mmu_extended_role").
The previous RFC (v5) can be read here:
https://www.spinics.net/lists/kvm/msg179441.html
Thanks to Samuel Laurén and Mathieu Tarral, the previous version has
been integrated and tested with libVMI.
KVM-VMI: https://github.com/KVM-VMI/kvm-vmi
Kernel: https://github.com/KVM-VMI/kvm/tree/kvmi
QEMU: https://github.com/KVM-VMI/qemu/tree/kvmi
(not all patches, but enough to work)
libVMI: https://github.com/KVM-VMI/libvmi/tree/kvmi
Thanks to Weijiang Yang, the previous version has been integrated and
tested with the SPP patch series.
https://github.com/adlazar/kvm/tree/kvmi-v5-spp
Quickstart:
https://github.com/adlazar/kvm/blob/kvmi-v5-spp/tools/kvm/kvmi/README
I hope this version will be merged into KVM-VMI project too.
Patches 1-20: unroll a big part of the KVM introspection subsystem,
sent in one patch in the previous versions.
Patches 21-24: extend the current page tracking code.
Patches 25-33: make use of page tracking to support the
KVMI_SET_PAGE_ACCESS introspection command and the KVMI_EVENT_PF event
(on EPT violations caused by the tracking settings).
Patches 34-42: include the SPP feature (Enable Sub-page
Write Protection Support), already sent to KVM list:
https://lore.kernel.org/lkml/[email protected]/
Patches 43-46: add the commands needed to use SPP.
Patches 47-63: unroll almost all the rest of the introspection code.
Patches 64-67: add single-stepping, mostly as a way to overcome the
unimplemented instructions, but also as a feature for the introspection
tool.
Patches 68-70: cover more cases related to EPT violations.
Patches 71-73: add the remote mapping feature, allowing the introspection
tool to map into its address space a page from guest memory.
Patches 74: add a fix to hypercall emulation.
Patches 75-76: disable some features/optimizations when the introspection
code is present.
Patches 77-78: add trace functions for the introspection code and change
some related to interrupts/exceptions injection.
Patches 79-92: new instruction for the x86 emulator, including cmpxchg
fixes.
To do:
- run stress tests with SPP enabled
- add introspection support for alternate EPT views (almost done)
- add introspection support for virtualization exceptions #VE (almost done)
- add KVM tests
Changes since v5:
- small changes to the protocol, but enough to make it backward
incompatible with v5
- fix CR3 interception (thanks to Mathieu Tarral for reporting the issue)
- add SPP support (thanks to Weijiang Yang)
- add two more ioctls in order to let userspace/QEMU control
the commands/events allowed for introspection
- extend the breakpoint event with the instruction length
- complete the descriptor table registers interception
- add new instructions to the x86 emulator
- move arch dependent code to arch/x86/kvm/
- lots of fixes, especially on page tracking, single-stepping, exception
injection and remote memory mapping
- the guests are much more stable (on pair with our introspection
products using Xen)
- speed improvements (the penalty on web browsing actions is 50% lower,
at least)
Adalbert Lazăr (25):
kvm: introspection: add basic ioctls (hook/unhook)
kvm: introspection: add permission access ioctls
kvm: introspection: add the read/dispatch message function
kvm: introspection: add KVMI_GET_VERSION
kvm: introspection: add KVMI_CONTROL_CMD_RESPONSE
kvm: introspection: honor the reply option when handling the
KVMI_GET_VERSION command
kvm: introspection: add KVMI_CHECK_COMMAND and KVMI_CHECK_EVENT
kvm: introspection: add KVMI_CONTROL_VM_EVENTS
kvm: introspection: add a jobs list to every introspected vCPU
kvm: introspection: make the vCPU wait even when its jobs list is
empty
kvm: introspection: add KVMI_EVENT_UNHOOK
kvm: x86: intercept the write access on sidt and other emulated
instructions
kvm: introspection: add KVMI_CONTROL_SPP
kvm: introspection: extend the internal database of tracked pages with
write_bitmap info
kvm: introspection: add KVMI_GET_PAGE_WRITE_BITMAP
kvm: introspection: add KVMI_SET_PAGE_WRITE_BITMAP
kvm: add kvm_vcpu_kick_and_wait()
kvm: introspection: add KVMI_PAUSE_VCPU and KVMI_EVENT_PAUSE_VCPU
kvm: x86: add kvm_arch_vcpu_set_guest_debug()
kvm: introspection: add custom input when single-stepping a vCPU
kvm: x86: keep the page protected if tracked by the introspection tool
kvm: x86: filter out access rights only when tracked by the
introspection tool
kvm: x86: disable gpa_available optimization in
emulator_read_write_onepage()
kvm: x86: disable EPT A/D bits if introspection is present
kvm: introspection: add trace functions
Marian Rotariu (1):
kvm: introspection: add KVMI_GET_CPUID
Mihai Donțu (47):
kvm: introduce KVMI (VM introspection subsystem)
kvm: introspection: add KVMI_GET_GUEST_INFO
kvm: introspection: handle introspection commands before returning to
guest
kvm: introspection: handle vCPU related introspection commands
kvm: introspection: handle events and event replies
kvm: introspection: introduce event actions
kvm: introspection: add KVMI_GET_VCPU_INFO
kvm: page track: add track_create_slot() callback
kvm: x86: provide all page tracking hooks with the guest virtual
address
kvm: page track: add support for preread, prewrite and preexec
kvm: x86: wire in the preread/prewrite/preexec page trackers
kvm: x86: add kvm_mmu_nested_pagefault()
kvm: introspection: use page track
kvm: x86: consult the page tracking from kvm_mmu_get_page() and
__direct_map()
kvm: introspection: add KVMI_CONTROL_EVENTS
kvm: x86: add kvm_spt_fault()
kvm: introspection: add KVMI_EVENT_PF
kvm: introspection: add KVMI_GET_PAGE_ACCESS
kvm: introspection: add KVMI_SET_PAGE_ACCESS
kvm: introspection: add KVMI_READ_PHYSICAL and KVMI_WRITE_PHYSICAL
kvm: introspection: add KVMI_GET_REGISTERS
kvm: introspection: add KVMI_SET_REGISTERS
kvm: introspection: add KVMI_INJECT_EXCEPTION + KVMI_EVENT_TRAP
kvm: introspection: add KVMI_CONTROL_CR and KVMI_EVENT_CR
kvm: introspection: add KVMI_CONTROL_MSR and KVMI_EVENT_MSR
kvm: introspection: add KVMI_GET_XSAVE
kvm: introspection: add KVMI_GET_MTRR_TYPE
kvm: introspection: add KVMI_EVENT_XSETBV
kvm: introspection: add KVMI_EVENT_BREAKPOINT
kvm: introspection: add KVMI_EVENT_HYPERCALL
kvm: introspection: use single stepping on unimplemented instructions
kvm: x86: emulate a guest page table walk on SPT violations due to A/D
bit updates
kvm: x86: do not unconditionally patch the hypercall instruction
during emulation
kvm: x86: emulate movsd xmm, m64
kvm: x86: emulate movss xmm, m32
kvm: x86: emulate movq xmm, m64
kvm: x86: emulate movq r, xmm
kvm: x86: emulate movd xmm, m32
kvm: x86: enable the half part of movss, movsd, movups
kvm: x86: emulate lfence
kvm: x86: emulate xorpd xmm2/m128, xmm1
kvm: x86: emulate xorps xmm/m128, xmm
kvm: x86: emulate fst/fstp m64fp
kvm: x86: make lock cmpxchg r, r/m atomic
kvm: x86: emulate lock cmpxchg8b atomically
kvm: x86: emulate lock cmpxchg16b m128
kvm: x86: fallback to the single-step on multipage CMPXCHG emulation
Mircea Cîrjaliu (5):
kvm: introspection: add vCPU related data
kvm: introspection: add KVMI_EVENT_CREATE_VCPU
mm: add support for remote mapping
kvm: introspection: add memory map/unmap support on the guest side
kvm: introspection: use remote mapping
Nicușor Cîțu (5):
kvm: x86: block any attempt to disable MSR interception if tracked by
introspection
kvm: introspection: add KVMI_EVENT_DESCRIPTOR
kvm: introspection: add single-stepping
kvm: introspection: add KVMI_EVENT_SINGLESTEP
kvm: x86: add tracepoints for interrupt and exception injections
Yang Weijiang (9):
Documentation: Introduce EPT based Subpage Protection
KVM: VMX: Add control flags for SPP enabling
KVM: VMX: Implement functions for SPPT paging setup
KVM: VMX: Introduce SPP access bitmap and operation functions
KVM: VMX: Add init/set/get functions for SPP
KVM: VMX: Introduce SPP user-space IOCTLs
KVM: VMX: Handle SPP induced vmexit and page fault
KVM: MMU: Enable Lazy mode SPPT setup
KVM: MMU: Handle host memory remapping and reclaim
Documentation/virtual/kvm/api.txt | 104 ++
Documentation/virtual/kvm/hypercalls.txt | 68 +-
Documentation/virtual/kvm/kvmi.rst | 1640 +++++++++++++++++
Documentation/virtual/kvm/spp_kvm.txt | 173 ++
arch/x86/Kconfig | 9 +
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/kvm_emulate.h | 3 +-
arch/x86/include/asm/kvm_host.h | 52 +-
arch/x86/include/asm/kvm_page_track.h | 33 +-
arch/x86/include/asm/kvmi_guest.h | 10 +
arch/x86/include/asm/kvmi_host.h | 51 +
arch/x86/include/asm/vmx.h | 12 +
arch/x86/include/uapi/asm/kvmi.h | 124 ++
arch/x86/include/uapi/asm/vmx.h | 2 +
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/cpu/intel.c | 4 +
arch/x86/kernel/kvmi_mem_guest.c | 26 +
arch/x86/kvm/Kconfig | 7 +
arch/x86/kvm/Makefile | 1 +
arch/x86/kvm/emulate.c | 315 +++-
arch/x86/kvm/kvmi.c | 1141 ++++++++++++
arch/x86/kvm/mmu.c | 645 ++++++-
arch/x86/kvm/mmu.h | 5 +
arch/x86/kvm/page_track.c | 147 +-
arch/x86/kvm/svm.c | 168 +-
arch/x86/kvm/trace.h | 118 +-
arch/x86/kvm/vmx/capabilities.h | 5 +
arch/x86/kvm/vmx/vmx.c | 347 +++-
arch/x86/kvm/vmx/vmx.h | 2 +
arch/x86/kvm/x86.c | 601 ++++++-
drivers/gpu/drm/i915/gvt/kvmgt.c | 2 +-
include/linux/kvm_host.h | 26 +
include/linux/kvmi.h | 68 +
include/linux/page-flags.h | 9 +-
include/linux/remote_mapping.h | 167 ++
include/linux/swait.h | 11 +
include/trace/events/kvmi.h | 680 +++++++
include/uapi/linux/kvm.h | 34 +
include/uapi/linux/kvm_para.h | 10 +-
include/uapi/linux/kvmi.h | 286 +++
include/uapi/linux/remote_mapping.h | 18 +
kernel/signal.c | 1 +
mm/Kconfig | 8 +
mm/Makefile | 1 +
mm/memory-failure.c | 69 +-
mm/migrate.c | 9 +-
mm/remote_mapping.c | 1834 +++++++++++++++++++
mm/rmap.c | 13 +-
mm/vmscan.c | 3 +-
virt/kvm/kvm_main.c | 70 +-
virt/kvm/kvmi.c | 2054 ++++++++++++++++++++++
virt/kvm/kvmi_int.h | 311 ++++
virt/kvm/kvmi_mem.c | 324 ++++
virt/kvm/kvmi_mem_guest.c | 651 +++++++
virt/kvm/kvmi_msg.c | 1236 +++++++++++++
55 files changed, 13485 insertions(+), 225 deletions(-)
create mode 100644 Documentation/virtual/kvm/kvmi.rst
create mode 100644 Documentation/virtual/kvm/spp_kvm.txt
create mode 100644 arch/x86/include/asm/kvmi_guest.h
create mode 100644 arch/x86/include/asm/kvmi_host.h
create mode 100644 arch/x86/include/uapi/asm/kvmi.h
create mode 100644 arch/x86/kernel/kvmi_mem_guest.c
create mode 100644 arch/x86/kvm/kvmi.c
create mode 100644 include/linux/kvmi.h
create mode 100644 include/linux/remote_mapping.h
create mode 100644 include/trace/events/kvmi.h
create mode 100644 include/uapi/linux/kvmi.h
create mode 100644 include/uapi/linux/remote_mapping.h
create mode 100644 mm/remote_mapping.c
create mode 100644 virt/kvm/kvmi.c
create mode 100644 virt/kvm/kvmi_int.h
create mode 100644 virt/kvm/kvmi_mem.c
create mode 100644 virt/kvm/kvmi_mem_guest.c
create mode 100644 virt/kvm/kvmi_msg.c
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