From 70367f091777419f42e5f68f4206deb641335877 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 2 Sep 2021 11:35:26 +0200 Subject: i386: Support KVM_CAP_HYPERV_ENFORCE_CPUID By default, KVM allows the guest to use all currently supported Hyper-V enlightenments when Hyper-V CPUID interface was exposed, regardless of if some features were not announced in guest visible CPUIDs. hv-enforce-cpuid feature alters this behavior and only allows the guest to use exposed Hyper-V enlightenments. The feature is supported by Linux >= 5.14 and is not enabled by default in QEMU. Signed-off-by: Vitaly Kuznetsov Message-Id: <20210902093530.345756-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- docs/hyperv.txt | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'docs/hyperv.txt') diff --git a/docs/hyperv.txt b/docs/hyperv.txt index 000638a..072709a 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -203,8 +203,11 @@ 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 -======================== +4. Supplementary features +========================= + +4.1. hv-passthrough +=================== In some cases (e.g. during development) it may make sense to use QEMU in 'pass-through' mode and give Windows guests all enlightenments currently supported by KVM. This pass-through mode is enabled by "hv-passthrough" CPU @@ -215,8 +218,16 @@ values from KVM to QEMU. "hv-passthrough" overrides all other "hv-*" settings on the command line. Also, enabling this flag effectively prevents migration as the list of enabled enlightenments may differ between target and destination hosts. +4.2. hv-enforce-cpuid +===================== +By default, KVM allows the guest to use all currently supported Hyper-V +enlightenments when Hyper-V CPUID interface was exposed, regardless of if +some features were not announced in guest visible CPUIDs. 'hv-enforce-cpuid' +feature alters this behavior and only allows the guest to use exposed Hyper-V +enlightenments. + -4. Useful links +5. Useful links ================ Hyper-V Top Level Functional specification and other information: https://github.com/MicrosoftDocs/Virtualization-Documentation -- cgit v1.1