[Qemu-devel] [PULL 10/16] kvm: make availability of Hyper-V enlightenments dependent on KVM_CAP_HYPERV

[Paolo Bonzini <pbonzini@redhat.com>]

The MS docs specify HV_X64_MSR_HYPERCALL as a mandatory interface,
thus we must provide the MSRs even if the user only specified
features that, like relaxed timing, in principle don't require them.
And the MSRs are only there if the hypervisor has KVM_CAP_HYPERV.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-i386/kvm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 5738911..e6831b2 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -72,6 +72,8 @@ static bool has_msr_misc_enable;
 static bool has_msr_bndcfgs;
 static bool has_msr_kvm_steal_time;
 static int lm_capable_kernel;
+static bool has_msr_hv_hypercall;
+static bool has_msr_hv_vapic;
 
 static bool has_msr_architectural_pmu;
 static uint32_t num_architectural_pmu_counters;
@@ -437,8 +439,10 @@ static bool hyperv_hypercall_available(X86CPU *cpu)
 
 static bool hyperv_enabled(X86CPU *cpu)
 {
-    return hyperv_hypercall_available(cpu) ||
-           cpu->hyperv_relaxed_timing;
+    CPUState *cs = CPU(cpu);
+    return kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV) > 0 &&
+           (hyperv_hypercall_available(cpu) ||
+            cpu->hyperv_relaxed_timing);
 }
 
 #define KVM_MAX_CPUID_ENTRIES  100
@@ -493,6 +497,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         if (cpu->hyperv_vapic) {
             c->eax |= HV_X64_MSR_HYPERCALL_AVAILABLE;
             c->eax |= HV_X64_MSR_APIC_ACCESS_AVAILABLE;
+            has_msr_hv_vapic = true;
         }
 
         c = &cpuid_data.entries[cpuid_i++];
@@ -500,7 +505,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         if (cpu->hyperv_relaxed_timing) {
             c->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
         }
-        if (cpu->hyperv_vapic) {
+        if (has_msr_hv_vapic) {
             c->eax |= HV_X64_APIC_ACCESS_RECOMMENDED;
         }
         c->ebx = cpu->hyperv_spinlock_attempts;
@@ -511,6 +516,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         c->ebx = 0x40;
 
         kvm_base = KVM_CPUID_SIGNATURE_NEXT;
+        has_msr_hv_hypercall = true;
     }
 
     memcpy(signature, "KVMKVMKVM\0\0\0", 12);
@@ -1223,11 +1229,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
             kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_CTRL,
                               env->msr_global_ctrl);
         }
-        if (hyperv_hypercall_available(cpu)) {
+        if (has_msr_hv_hypercall) {
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_GUEST_OS_ID, 0);
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_HYPERCALL, 0);
         }
-        if (cpu->hyperv_vapic) {
+        if (has_msr_hv_vapic) {
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_APIC_ASSIST_PAGE, 0);
         }
 
-- 
1.8.3.1