From decb4f2013141906913b2c358f043337ab982d3e Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Thu, 22 Apr 2021 18:11:21 +0200
Subject: [PATCH] i386: move eVMCS enablement to hyperv_init_vcpu()

hyperv_expand_features() will be called before we create vCPU so
evmcs enablement should go away. hyperv_init_vcpu() looks like the
right place.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20210422161130.652779-11-vkuznets@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/kvm/kvm.c | 60 ++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 23 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 10c836a2bf..57282246c6 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -963,6 +963,7 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs)
 {
     struct kvm_cpuid2 *cpuid;
     int max = 7; /* 0x40000000..0x40000005, 0x4000000A */
+    int i;
 
     /*
      * When the buffer is too small, KVM_GET_SUPPORTED_HV_CPUID fails with
@@ -972,6 +973,22 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs)
     while ((cpuid = try_get_hv_cpuid(cs, max)) == NULL) {
         max++;
     }
+
+    /*
+     * KVM_GET_SUPPORTED_HV_CPUID does not set EVMCS CPUID bit before
+     * KVM_CAP_HYPERV_ENLIGHTENED_VMCS is enabled but we want to get the
+     * information early, just check for the capability and set the bit
+     * manually.
+     */
+    if (kvm_check_extension(cs->kvm_state,
+                            KVM_CAP_HYPERV_ENLIGHTENED_VMCS) > 0) {
+        for (i = 0; i < cpuid->nent; i++) {
+            if (cpuid->entries[i].function == HV_CPUID_ENLIGHTMENT_INFO) {
+                cpuid->entries[i].eax |= HV_ENLIGHTENED_VMCS_RECOMMENDED;
+            }
+        }
+    }
+
     return cpuid;
 }
 
@@ -1201,24 +1218,6 @@ static int hyperv_expand_features(CPUState *cs)
     if (!hyperv_enabled(cpu))
         return 0;
 
-    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS) ||
-        cpu->hyperv_passthrough) {
-        uint16_t evmcs_version;
-
-        r = kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0,
-                                (uintptr_t)&evmcs_version);
-
-        if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS) && r) {
-            fprintf(stderr, "Hyper-V %s is not supported by kernel\n",
-                    kvm_hyperv_properties[HYPERV_FEAT_EVMCS].desc);
-            return -ENOSYS;
-        }
-
-        if (!r) {
-            cpu->hyperv_nested[0] = evmcs_version;
-        }
-    }
-
     if (cpu->hyperv_passthrough) {
         cpu->hyperv_vendor_id[0] =
             hv_cpuid_get_host(cs, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, R_EBX);
@@ -1456,6 +1455,21 @@ static int hyperv_init_vcpu(X86CPU *cpu)
         }
     }
 
+    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS)) {
+        uint16_t evmcs_version;
+
+        ret = kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0,
+                                  (uintptr_t)&evmcs_version);
+
+        if (ret < 0) {
+            fprintf(stderr, "Hyper-V %s is not supported by kernel\n",
+                    kvm_hyperv_properties[HYPERV_FEAT_EVMCS].desc);
+            return ret;
+        }
+
+        cpu->hyperv_nested[0] = evmcs_version;
+    }
+
     return 0;
 }
 
@@ -1520,6 +1534,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
     }
 
     if (hyperv_enabled(cpu)) {
+        r = hyperv_init_vcpu(cpu);
+        if (r) {
+            return r;
+        }
+
         cpuid_i = hyperv_fill_cpuids(cs, cpuid_data.entries);
         kvm_base = KVM_CPUID_SIGNATURE_NEXT;
         has_msr_hv_hypercall = true;
@@ -1869,11 +1888,6 @@ int kvm_arch_init_vcpu(CPUState *cs)
 
     kvm_init_msrs(cpu);
 
-    r = hyperv_init_vcpu(cpu);
-    if (r) {
-        goto fail;
-    }
-
     return 0;
 
  fail: