Re: [PATCH v8 3/9] i386: hardcode supported eVMCS version to '1'

[Eduardo Habkost]

On Tue, Jun 08, 2021 at 02:08:11PM +0200, Vitaly Kuznetsov wrote:
> 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.

Should we rewrite this as "it wouldn't be possible to migrate",
as this patch fixes the problem and makes it possible?

> 
> 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 <vkuznets@redhat.com>

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

-- 
Eduardo