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Diffstat (limited to 'docs/system/cpu-models-x86.rst.inc')
| -rw-r--r-- | docs/system/cpu-models-x86.rst.inc | 57 |
1 files changed, 55 insertions, 2 deletions
diff --git a/docs/system/cpu-models-x86.rst.inc b/docs/system/cpu-models-x86.rst.inc index cbad930c70..9a2327828e 100644 --- a/docs/system/cpu-models-x86.rst.inc +++ b/docs/system/cpu-models-x86.rst.inc @@ -49,10 +49,15 @@ mixture of host CPU models between machines, if live migration compatibility is required, use the newest CPU model that is compatible across all desired hosts. -``Skylake-Server``, ``Skylake-Server-IBRS`` +``Cascadelake-Server``, ``Cascadelake-Server-noTSX`` + Intel Xeon Processor (Cascade Lake, 2019), with "stepping" levels 6 + or 7 only. (The Cascade Lake Xeon processor with *stepping 5 is + vulnerable to MDS variants*.) + +``Skylake-Server``, ``Skylake-Server-IBRS``, ``Skylake-Server-IBRS-noTSX`` Intel Xeon Processor (Skylake, 2016) -``Skylake-Client``, ``Skylake-Client-IBRS`` +``Skylake-Client``, ``Skylake-Client-IBRS``, ``Skylake-Client-noTSX-IBRS}`` Intel Core Processor (Skylake, 2015) ``Broadwell``, ``Broadwell-IBRS``, ``Broadwell-noTSX``, ``Broadwell-noTSX-IBRS`` @@ -148,6 +153,54 @@ features are included if using "Host passthrough" or "Host model". Requires the host CPU microcode to support this feature before it can be used for guest CPUs. +``mds-no`` + Recommended to inform the guest OS that the host is *not* vulnerable + to any of the MDS variants ([MFBDS] CVE-2018-12130, [MLPDS] + CVE-2018-12127, [MSBDS] CVE-2018-12126). + + This is an MSR (Model-Specific Register) feature rather than a CPUID feature, + so it will not appear in the Linux ``/proc/cpuinfo`` in the host or + guest. Instead, the host kernel uses it to populate the MDS + vulnerability file in ``sysfs``. + + So it should only be enabled for VMs if the host reports @code{Not + affected} in the ``/sys/devices/system/cpu/vulnerabilities/mds`` file. + +``taa-no`` + Recommended to inform that the guest that the host is ``not`` + vulnerable to CVE-2019-11135, TSX Asynchronous Abort (TAA). + + This too is an MSR feature, so it does not show up in the Linux + ``/proc/cpuinfo`` in the host or guest. + + It should only be enabled for VMs if the host reports ``Not affected`` + in the ``/sys/devices/system/cpu/vulnerabilities/tsx_async_abort`` + file. + +``tsx-ctrl`` + Recommended to inform the guest that it can disable the Intel TSX + (Transactional Synchronization Extensions) feature; or, if the + processor is vulnerable, use the Intel VERW instruction (a + processor-level instruction that performs checks on memory access) as + a mitigation for the TAA vulnerability. (For details, refer to + Intel's `deep dive into MDS + <https://software.intel.com/security-software-guidance/insights/deep-dive-intel-analysis-microarchitectural-data-sampling>`_.) + + Expose this to the guest OS if and only if: (a) the host has TSX + enabled; *and* (b) the guest has ``rtm`` CPU flag enabled. + + By disabling TSX, KVM-based guests can avoid paying the price of + mitigating TSX-based attacks. + + Note that ``tsx-ctrl`` too is an MSR feature, so it does not show + up in the Linux ``/proc/cpuinfo`` in the host or guest. + + To validate that Intel TSX is indeed disabled for the guest, there are + two ways: (a) check for the *absence* of ``rtm`` in the guest's + ``/proc/cpuinfo``; or (b) the + ``/sys/devices/system/cpu/vulnerabilities/tsx_async_abort`` file in + the guest should report ``Mitigation: TSX disabled``. + Preferred CPU models for AMD x86 hosts ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |