i386: HV_HYPERCALL_AVAILABLE privilege bit is always needed
commitb26f68c36bf6edaaa224f8a6ab285394af4d0f8c
authorVitaly Kuznetsov <vkuznets@redhat.com>
Tue, 8 Jun 2021 12:08:15 +0000 (8 14:08 +0200)
committerEduardo Habkost <ehabkost@redhat.com>
Tue, 13 Jul 2021 13:13:29 +0000 (13 09:13 -0400)
tree2cea8c96e1c39ca417cbf4c19a82ce94a58d4d7a
parent5ce48fa354f2270731e20f81dbb7ff191630c321
i386: HV_HYPERCALL_AVAILABLE privilege bit is always needed

According to TLFS, Hyper-V guest is supposed to check
HV_HYPERCALL_AVAILABLE privilege bit before accessing
HV_X64_MSR_GUEST_OS_ID/HV_X64_MSR_HYPERCALL MSRs but at least some
Windows versions ignore that. As KVM is very permissive and allows
accessing these MSRs unconditionally, no issue is observed. We may,
however, want to tighten the checks eventually. Conforming to the
spec is probably also a good idea.

Enable HV_HYPERCALL_AVAILABLE bit unconditionally.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210608120817.1325125-8-vkuznets@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
target/i386/kvm/kvm.c