[PATCH v4 1/6] i386: Use hv_build_cpuid_leaf() for HV_CPUID_NESTED_FEATURES

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Previously, HV_CPUID_NESTED_FEATURES.EAX CPUID leaf was handled differently
as it was only used to encode the supported eVMCS version range. In fact,
there are also feature (e.g. Enlightened MSR-Bitmap) bits there. In
preparation to adding these features, move HV_CPUID_NESTED_FEATURES leaf
handling to hv_build_cpuid_leaf() and drop now-unneeded 'hyperv_nested'.

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 target/i386/cpu.h     |  1 -
 target/i386/kvm/kvm.c | 25 +++++++++++++++----------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 0d528ac58f32..2e918daf6bef 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1804,7 +1804,6 @@ struct ArchCPU {
     uint32_t hyperv_vendor_id[3];
     uint32_t hyperv_interface_id[4];
     uint32_t hyperv_limits[3];
-    uint32_t hyperv_nested[4];
     bool hyperv_enforce_cpuid;
     uint32_t hyperv_ver_id_build;
     uint16_t hyperv_ver_id_major;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a9ee8eebd76f..93bfefa4a79e 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -831,6 +831,8 @@ static bool tsc_is_stable_and_known(CPUX86State *env)
         || env->user_tsc_khz;
 }
 
+#define DEFAULT_EVMCS_VERSION ((1 << 8) | 1)
+
 static struct {
     const char *desc;
     struct {
@@ -1254,6 +1256,13 @@ static uint32_t hv_build_cpuid_leaf(CPUState *cs, uint32_t func, int reg)
         }
     }
 
+    /* HV_CPUID_NESTED_FEATURES.EAX also encodes the supported eVMCS range */
+    if (func == HV_CPUID_NESTED_FEATURES && reg == R_EAX) {
+        if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS)) {
+            r |= DEFAULT_EVMCS_VERSION;
+        }
+    }
+
     return r;
 }
 
@@ -1384,11 +1393,11 @@ static int hyperv_fill_cpuids(CPUState *cs,
     struct kvm_cpuid_entry2 *c;
     uint32_t signature[3];
     uint32_t cpuid_i = 0, max_cpuid_leaf = 0;
+    uint32_t nested_eax =
+        hv_build_cpuid_leaf(cs, HV_CPUID_NESTED_FEATURES, R_EAX);
 
-    max_cpuid_leaf = HV_CPUID_IMPLEMENT_LIMITS;
-    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS)) {
-        max_cpuid_leaf = MAX(max_cpuid_leaf, HV_CPUID_NESTED_FEATURES);
-    }
+    max_cpuid_leaf = nested_eax ? HV_CPUID_NESTED_FEATURES :
+        HV_CPUID_IMPLEMENT_LIMITS;
 
     if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNDBG)) {
         max_cpuid_leaf =
@@ -1461,7 +1470,7 @@ static int hyperv_fill_cpuids(CPUState *cs,
     c->ecx = cpu->hyperv_limits[1];
     c->edx = cpu->hyperv_limits[2];
 
-    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS)) {
+    if (nested_eax) {
         uint32_t function;
 
         /* Create zeroed 0x40000006..0x40000009 leaves */
@@ -1473,7 +1482,7 @@ static int hyperv_fill_cpuids(CPUState *cs,
 
         c = &cpuid_ent[cpuid_i++];
         c->function = HV_CPUID_NESTED_FEATURES;
-        c->eax = cpu->hyperv_nested[0];
+        c->eax = nested_eax;
     }
 
     if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNDBG)) {
@@ -1522,8 +1531,6 @@ static bool evmcs_version_supported(uint16_t evmcs_version,
         (max_version <= max_supported_version);
 }
 
-#define DEFAULT_EVMCS_VERSION ((1 << 8) | 1)
-
 static int hyperv_init_vcpu(X86CPU *cpu)
 {
     CPUState *cs = CPU(cpu);
@@ -1620,8 +1627,6 @@ static int hyperv_init_vcpu(X86CPU *cpu)
                          supported_evmcs_version >> 8);
             return -ENOTSUP;
         }
-
-        cpu->hyperv_nested[0] = evmcs_version;
     }
 
     if (cpu->hyperv_enforce_cpuid) {
-- 
2.35.3