i386: Implement pseudo 'hv-avic' ('hv-apicv') enlightenment
The enlightenment allows to use Hyper-V SynIC with hardware APICv/AVIC
enabled. Normally, Hyper-V SynIC disables these hardware features and
suggests the guest to use paravirtualized AutoEOI feature. Linux-4.15
gains support for conditional APICv/AVIC disablement, the feature
stays on until the guest tries to use AutoEOI feature with SynIC. With
'HV_DEPRECATING_AEOI_RECOMMENDED' bit exposed, modern enough Windows/
Hyper-V versions should follow the recommendation and not use the
(unwanted) feature.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210902093530.345756-7-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 072709a..cd1ea3b 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -189,7 +189,15 @@
Requires: hv-vpindex, hv-synic, hv-time, hv-stimer
-3.17. hv-no-nonarch-coresharing=on/off/auto
+3.18. hv-avic (hv-apicv)
+=======================
+The enlightenment allows to use Hyper-V SynIC with hardware APICv/AVIC enabled.
+Normally, Hyper-V SynIC disables these hardware feature and suggests the guest
+to use paravirtualized AutoEOI feature.
+Note: enabling this feature on old hardware (without APICv/AVIC support) may
+have negative effect on guest's performace.
+
+3.19. 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
