kvm: Enable -cpu option to hide KVM

The latest Nvidia driver (337.88) specifically checks for KVM as the
hypervisor and reports Code 43 for the driver in a Windows guest when
found.  Removing or changing the KVM signature is sufficient for the
driver to load and work.  This patch adds an option to easily allow
the KVM hypervisor signature to be hidden using '-cpu kvm=off'.  We
continue to expose KVM via the cpuid value by default.  The state of
this option does not supercede or replace -enable-kvm or the accel=kvm
machine option.  This only changes the visibility of KVM to the guest
and paravirtual features specifically tied to the KVM cpuid.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index e9b3d577b3d8b76314405016119cd92defffe9f5..0808cfc67df5db460ba2e28d83c3b54ecbe1c767 100644 (file)
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -87,6 +87,7 @@ typedef struct X86CPU {
     bool hyperv_time;
     bool check_cpuid;
     bool enforce_cpuid;
+    bool expose_kvm;
 
     /* if true the CPUID code directly forward host cache leaves to the guest */
     bool cache_info_passthrough;

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 042a48d70301c6659a7dd456056e3935ff3e08f2..cbf1d979cbf6bb5fd66a717cbb83cd4b26baf91c 100644 (file)
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2792,6 +2792,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("hv-time", X86CPU, hyperv_time, false),
     DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, false),
     DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
+    DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
     DEFINE_PROP_END_OF_LIST()
 };
 

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 3931d4c340570f50053942c1aef0b50b978add60..40cd4b84afb1e8981e8d56ea70db8bcc6080efe5 100644 (file)
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -528,23 +528,25 @@ int kvm_arch_init_vcpu(CPUState *cs)
         has_msr_hv_hypercall = true;
     }
 
-    memcpy(signature, "KVMKVMKVM\0\0\0", 12);
-    c = &cpuid_data.entries[cpuid_i++];
-    c->function = KVM_CPUID_SIGNATURE | kvm_base;
-    c->eax = 0;
-    c->ebx = signature[0];
-    c->ecx = signature[1];
-    c->edx = signature[2];
+    if (cpu->expose_kvm) {
+        memcpy(signature, "KVMKVMKVM\0\0\0", 12);
+        c = &cpuid_data.entries[cpuid_i++];
+        c->function = KVM_CPUID_SIGNATURE | kvm_base;
+        c->eax = 0;
+        c->ebx = signature[0];
+        c->ecx = signature[1];
+        c->edx = signature[2];
 
-    c = &cpuid_data.entries[cpuid_i++];
-    c->function = KVM_CPUID_FEATURES | kvm_base;
-    c->eax = env->features[FEAT_KVM];
+        c = &cpuid_data.entries[cpuid_i++];
+        c->function = KVM_CPUID_FEATURES | kvm_base;
+        c->eax = env->features[FEAT_KVM];
 
-    has_msr_async_pf_en = c->eax & (1 << KVM_FEATURE_ASYNC_PF);
+        has_msr_async_pf_en = c->eax & (1 << KVM_FEATURE_ASYNC_PF);
 
-    has_msr_pv_eoi_en = c->eax & (1 << KVM_FEATURE_PV_EOI);
+        has_msr_pv_eoi_en = c->eax & (1 << KVM_FEATURE_PV_EOI);
 
-    has_msr_kvm_steal_time = c->eax & (1 << KVM_FEATURE_STEAL_TIME);
+        has_msr_kvm_steal_time = c->eax & (1 << KVM_FEATURE_STEAL_TIME);
+    }
 
     cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);