i386/kvm: expose HV_CPUID_ENLIGHTMENT_INFO.EAX and HV_CPUID_NESTED_FEATURES.EAX as feature words

It was found that QMP users of QEMU (e.g. libvirt) may need
HV_CPUID_ENLIGHTMENT_INFO.EAX/HV_CPUID_NESTED_FEATURES.EAX information. In
particular, 'hv_tlbflush' and 'hv_evmcs' enlightenments are only exposed in
HV_CPUID_ENLIGHTMENT_INFO.EAX.

HV_CPUID_NESTED_FEATURES.EAX is exposed for two reasons: convenience
(we don't need to export it from hyperv_handle_properties() and as
future-proof for Enlightened MSR-Bitmap, PV EPT invalidation and
direct virtual flush features.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20181126135958.20956-1-vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

target/i386/cpu.c

@@ -980,6 +980,36 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         },
         .cpuid = { .eax = 0x40000003, .reg = R_EDX, },
     },
+    [FEAT_HV_RECOMM_EAX] = {
+        .type = CPUID_FEATURE_WORD,
+        .feat_names = {
+            NULL /* hv_recommend_pv_as_switch */,
+            NULL /* hv_recommend_pv_tlbflush_local */,
+            NULL /* hv_recommend_pv_tlbflush_remote */,
+            NULL /* hv_recommend_msr_apic_access */,
+            NULL /* hv_recommend_msr_reset */,
+            NULL /* hv_recommend_relaxed_timing */,
+            NULL /* hv_recommend_dma_remapping */,
+            NULL /* hv_recommend_int_remapping */,
+            NULL /* hv_recommend_x2apic_msrs */,
+            NULL /* hv_recommend_autoeoi_deprecation */,
+            NULL /* hv_recommend_pv_ipi */,
+            NULL /* hv_recommend_ex_hypercalls */,
+            NULL /* hv_hypervisor_is_nested */,
+            NULL /* hv_recommend_int_mbec */,
+            NULL /* hv_recommend_evmcs */,
+            NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+        },
+        .cpuid = { .eax = 0x40000004, .reg = R_EAX, },
+    },
+    [FEAT_HV_NESTED_EAX] = {
+        .type = CPUID_FEATURE_WORD,
+        .cpuid = { .eax = 0x4000000A, .reg = R_EAX, },
+    },
     [FEAT_SVM] = {
         .type = CPUID_FEATURE_WORD,
         .feat_names = {

target/i386/cpu.h

@@ -497,6 +497,8 @@ typedef enum FeatureWord {
     FEAT_HYPERV_EAX,    /* CPUID[4000_0003].EAX */
     FEAT_HYPERV_EBX,    /* CPUID[4000_0003].EBX */
     FEAT_HYPERV_EDX,    /* CPUID[4000_0003].EDX */
+    FEAT_HV_RECOMM_EAX, /* CPUID[4000_0004].EAX */
+    FEAT_HV_NESTED_EAX, /* CPUID[4000_000A].EAX */
     FEAT_SVM,           /* CPUID[8000_000A].EDX */
     FEAT_XSAVE,         /* CPUID[EAX=0xd,ECX=1].EAX */
     FEAT_6_EAX,         /* CPUID[6].EAX */

target/i386/kvm.c

@@ -798,6 +798,48 @@ static int hyperv_handle_properties(CPUState *cs)
         }
         env->features[FEAT_HYPERV_EAX] |= HV_SYNTIMERS_AVAILABLE;
     }
+    if (cpu->hyperv_relaxed_timing) {
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_RELAXED_TIMING_RECOMMENDED;
+    }
+    if (cpu->hyperv_vapic) {
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_APIC_ACCESS_RECOMMENDED;
+    }
+    if (cpu->hyperv_tlbflush) {
+        if (kvm_check_extension(cs->kvm_state,
+                                KVM_CAP_HYPERV_TLBFLUSH) <= 0) {
+            fprintf(stderr, "Hyper-V TLB flush support "
+                    "(requested by 'hv-tlbflush' cpu flag) "
+                    " is not supported by kernel\n");
+            return -ENOSYS;
+        }
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_REMOTE_TLB_FLUSH_RECOMMENDED;
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
+    }
+    if (cpu->hyperv_ipi) {
+        if (kvm_check_extension(cs->kvm_state,
+                                KVM_CAP_HYPERV_SEND_IPI) <= 0) {
+            fprintf(stderr, "Hyper-V IPI send support "
+                    "(requested by 'hv-ipi' cpu flag) "
+                    " is not supported by kernel\n");
+            return -ENOSYS;
+        }
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_CLUSTER_IPI_RECOMMENDED;
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
+    }
+    if (cpu->hyperv_evmcs) {
+        uint16_t evmcs_version;
+
+        if (kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0,
+                                (uintptr_t)&evmcs_version)) {
+            fprintf(stderr, "Hyper-V Enlightened VMCS "
+                    "(requested by 'hv-evmcs' cpu flag) "
+                    "is not supported by kernel\n");
+            return -ENOSYS;
+        }
+        env->features[FEAT_HV_RECOMM_EAX] |= HV_ENLIGHTENED_VMCS_RECOMMENDED;
+        env->features[FEAT_HV_NESTED_EAX] = evmcs_version;
+    }
+
     return 0;
 }
 
@@ -879,7 +921,6 @@ int kvm_arch_init_vcpu(CPUState *cs)
     uint32_t unused;
     struct kvm_cpuid_entry2 *c;
     uint32_t signature[3];
-    uint16_t evmcs_version;
     int kvm_base = KVM_CPUID_SIGNATURE;
     int r;
     Error *local_err = NULL;
@@ -954,44 +995,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
 
         c = &cpuid_data.entries[cpuid_i++];
         c->function = HV_CPUID_ENLIGHTMENT_INFO;
-        if (cpu->hyperv_relaxed_timing) {
+
-            c->eax |= HV_RELAXED_TIMING_RECOMMENDED;
+        c->eax = env->features[FEAT_HV_RECOMM_EAX];
-        }
-        if (cpu->hyperv_vapic) {
-            c->eax |= HV_APIC_ACCESS_RECOMMENDED;
-        }
-        if (cpu->hyperv_tlbflush) {
-            if (kvm_check_extension(cs->kvm_state,
-                                    KVM_CAP_HYPERV_TLBFLUSH) <= 0) {
-                fprintf(stderr, "Hyper-V TLB flush support "
-                        "(requested by 'hv-tlbflush' cpu flag) "
-                        " is not supported by kernel\n");
-                return -ENOSYS;
-            }
-            c->eax |= HV_REMOTE_TLB_FLUSH_RECOMMENDED;
-            c->eax |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
-        }
-        if (cpu->hyperv_ipi) {
-            if (kvm_check_extension(cs->kvm_state,
-                                    KVM_CAP_HYPERV_SEND_IPI) <= 0) {
-                fprintf(stderr, "Hyper-V IPI send support "
-                        "(requested by 'hv-ipi' cpu flag) "
-                        " is not supported by kernel\n");
-                return -ENOSYS;
-            }
-            c->eax |= HV_CLUSTER_IPI_RECOMMENDED;
-            c->eax |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
-        }
-        if (cpu->hyperv_evmcs) {
-            if (kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0,
-                                    (uintptr_t)&evmcs_version)) {
-                fprintf(stderr, "Hyper-V Enlightened VMCS "
-                        "(requested by 'hv-evmcs' cpu flag) "
-                        "is not supported by kernel\n");
-                return -ENOSYS;
-            }
-            c->eax |= HV_ENLIGHTENED_VMCS_RECOMMENDED;
-        }
         c->ebx = cpu->hyperv_spinlock_attempts;
 
         c = &cpuid_data.entries[cpuid_i++];
@@ -1015,7 +1020,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
 
             c = &cpuid_data.entries[cpuid_i++];
             c->function = HV_CPUID_NESTED_FEATURES;
-            c->eax = evmcs_version;
+            c->eax = env->features[FEAT_HV_NESTED_EAX];
         }
     }