From 07454e2ea84ee9be298c96d9730dc82abfb1488a Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 8 Jun 2021 14:08:11 +0200 Subject: i386: hardcode supported eVMCS version to '1' Currently, the only eVMCS version, supported by KVM (and described in TLFS) is '1'. When Enlightened VMCS feature is enabled, QEMU takes the supported eVMCS version range (from KVM_CAP_HYPERV_ENLIGHTENED_VMCS enablement) and puts it to guest visible CPUIDs. When (and if) eVMCS ver.2 appears a problem on migration is expected: it doesn't seem to be possible to migrate from a host supporting eVMCS ver.2 to a host, which only support eVMCS ver.1. Hardcode eVMCS ver.1 as the result of 'hv-evmcs' enablement for now. Newer eVMCS versions will have to have their own enablement options (e.g. 'hv-evmcs=2'). Signed-off-by: Vitaly Kuznetsov Reviewed-by: Eduardo Habkost Message-Id: <20210608120817.1325125-4-vkuznets@redhat.com> Signed-off-by: Eduardo Habkost --- docs/hyperv.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'docs') diff --git a/docs/hyperv.txt b/docs/hyperv.txt index a51953d..000638a 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -170,7 +170,7 @@ Recommended: hv-frequencies 3.16. hv-evmcs =============== The enlightenment is nested specific, it targets Hyper-V on KVM guests. When -enabled, it provides Enlightened VMCS feature to the guest. The feature +enabled, it provides Enlightened VMCS version 1 feature to the guest. The feature implements paravirtualized protocol between L0 (KVM) and L1 (Hyper-V) hypervisors making L2 exits to the hypervisor faster. The feature is Intel-only. Note: some virtualization features (e.g. Posted Interrupts) are disabled when -- cgit v1.1