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[Qemu-devel] [PATCH v4 2/2] i386/kvm: expose Hyper-V frequency MSRs with


From: Vitaly Kuznetsov
Subject: [Qemu-devel] [PATCH v4 2/2] i386/kvm: expose Hyper-V frequency MSRs with reenlightenment
Date: Thu, 22 Mar 2018 14:13:58 +0100

We can also expose Hyper-V frequency MSRs when reenlightenment feature is
enabled and TSC frequency is known, Hyper-V on KVM will provide stable TSC
page clocksources to its guests.

Signed-off-by: Vitaly Kuznetsov <address@hidden>
---
- Expose frequency MSRs only when either INVTSC or Reenlightenment is
  provided [Paolo Bonzini]
---
 target/i386/kvm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 75f4e1d69e..2c3c19d690 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -651,7 +651,8 @@ static int hyperv_handle_properties(CPUState *cs)
         env->features[FEAT_HYPERV_EAX] |= HV_TIME_REF_COUNT_AVAILABLE;
         env->features[FEAT_HYPERV_EAX] |= HV_REFERENCE_TSC_AVAILABLE;
 
-        if (has_msr_hv_frequencies && tsc_is_stable_and_known(env)) {
+        if (has_msr_hv_frequencies && env->tsc_khz &&
+            (tsc_is_stable_and_known(env) || cpu->hyperv_reenlightenment)) {
             env->features[FEAT_HYPERV_EAX] |= HV_ACCESS_FREQUENCY_MSRS;
             env->features[FEAT_HYPERV_EDX] |= HV_FREQUENCY_MSRS_AVAILABLE;
         }
-- 
2.14.3




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