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Diffstat (limited to 'docs/hyperv.txt')
| -rw-r--r-- | docs/hyperv.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/docs/hyperv.txt b/docs/hyperv.txt index 8fdf25c829..6518b716a9 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -184,6 +184,19 @@ enabled. Requires: hv-vpindex, hv-synic, hv-time, hv-stimer +3.17. hv-no-nonarch-coresharing=on/off/auto +=========================================== +This enlightenment tells guest OS that virtual processors will never share a +physical core unless they are reported as sibling SMT threads. This information +is required by Windows and Hyper-V guests to properly mitigate SMT related CPU +vulnerabilities. +When the option is set to 'auto' QEMU will enable the feature only when KVM +reports that non-architectural coresharing is impossible, this means that +hyper-threading is not supported or completely disabled on the host. This +setting also prevents migration as SMT settings on the destination may differ. +When the option is set to 'on' QEMU will always enable the feature, regardless +of host setup. To keep guests secure, this can only be used in conjunction with +exposing correct vCPU topology and vCPU pinning. 4. Development features ======================== |