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authorVitaly Kuznetsov <vkuznets@redhat.com>2019-05-17 16:19:20 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2019-06-21 02:29:38 +0200
commite48ddcc6ce13323087133f5922f8eb2fe516817b (patch)
tree95ec7889bab11bbfba0aefef2cebed488b814bdb /docs/hyperv.txt
parentfb19f72b774ce47cd26955ad61547bc3f7f02626 (diff)
i386/kvm: implement 'hv-passthrough' mode
In many case we just want to give Windows guests all currently supported Hyper-V enlightenments and that's where this new mode may come handy. We pass through what was returned by KVM_GET_SUPPORTED_HV_CPUID. hv_cpuid_check_and_set() is modified to also set cpu->hyperv_* flags as we may want to check them later (and we actually do for hv_runtime, hv_synic,...). 'hv-passthrough' is a development only feature, a migration blocker is added to prevent issues while migrating between hosts with different feature sets. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20190517141924.19024-6-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index c423e0fca2..beadb2d0d4 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -175,6 +175,16 @@ without the feature to find out if enabling it is beneficial.
Requires: hv-vapic
+4. Development features
+========================
+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
+flag.
+Note: enabling this flag effectively prevents migration as supported features
+may differ between target and destination.
+
+
4. Useful links
================
Hyper-V Top Level Functional specification and other information: