[PULL,5/5] i386/kvm: add a comment explaining why .feat_names are commented out for Hyper-V feature bits
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Message ID 20190114143432.4771-6-ehabkost@redhat.com
State New
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Series
  • [PULL,1/5] i386/kvm: expose HV_CPUID_ENLIGHTMENT_INFO.EAX and HV_CPUID_NESTED_FEATURES.EAX as feature words
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Commit Message

Eduardo Habkost Jan. 14, 2019, 2:34 p.m. UTC
From: Vitaly Kuznetsov <vkuznets@redhat.com>

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 <vkuznets@redhat.com>
Message-Id: <20181221141604.16935-1-vkuznets@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/cpu.c | 7 +++++++
 1 file changed, 7 insertions(+)

Patch
diff mbox series

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 3ece83696e..2f5412592d 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 = {