From 61470c276a7785f3615da564f15a5c2368354638 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 18 Jan 2019 11:57:05 +0000 Subject: [PATCH 2/2] i386/kvm: add a comment explaining why .feat_names are commented out for Hyper-V feature bits RH-Author: Vitaly Kuznetsov Message-id: <20190118115705.19731-3-vkuznets@redhat.com> Patchwork-id: 84048 O-Subject: [RHEL8 qemu-kvm PATCH 2/2] i386/kvm: add a comment explaining why .feat_names are commented out for Hyper-V feature bits Bugzilla: 1653511 RH-Acked-by: Mohammed Gamal RH-Acked-by: Eduardo Otubo RH-Acked-by: Eduardo Habkost Hyper-V .feat_names are, unlike hardware features, commented out and it is not obvious why we do that. Document the current status quo. Signed-off-by: Vitaly Kuznetsov Message-Id: <20181221141604.16935-1-vkuznets@redhat.com> Signed-off-by: Eduardo Habkost (cherry picked from commit abd5fc4c862d033a989552914149f01c9476bb16) Signed-off-by: Danilo C. L. de Paula --- target/i386/cpu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 460fe06..8570b25 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -929,6 +929,13 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { */ .no_autoenable_flags = ~0U, }, + /* + * .feat_names are commented out for Hyper-V enlightenments because we + * don't want to have two different ways for enabling them on QEMU command + * line. Some features (e.g. "hyperv_time", "hyperv_vapic", ...) require + * enabling several feature bits simultaneously, exposing these bits + * individually may just confuse guests. + */ [FEAT_HYPERV_EAX] = { .type = CPUID_FEATURE_WORD, .feat_names = { -- 1.8.3.1