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From a8a32dd460a1d838cfe97ec53a2eb76c018c5dbf Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 22 Jul 2019 18:22:19 +0100
Subject: [PATCH 38/39] target/i386: skip KVM_GET/SET_NESTED_STATE if VMX
 disabled, or for SVM

RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20190722182220.19374-18-pbonzini@redhat.com>
Patchwork-id: 89636
O-Subject: [RHEL-8.1.0 PATCH qemu-kvm v3 17/18] target/i386: skip KVM_GET/SET_NESTED_STATE if VMX disabled, or for SVM
Bugzilla: 1689269
RH-Acked-by: Peter Xu <zhexu@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Do not allocate env->nested_state unless we later need to migrate the
nested virtualization state.

With this change, nested_state_needed() will return false if the
VMX flag is not included in the virtual machine.  KVM_GET/SET_NESTED_STATE
is also disabled for SVM which is safer (we know that at least the NPT
root and paging mode have to be saved/loaded), and thus the corresponding
subsection can go away as well.

Inspired by a patch from Liran Alon.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 1e44f3ab71fb4291d266a264f7c207ae5c6d59b2)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 target/i386/kvm.c     | 16 ++++++++--------
 target/i386/machine.c | 21 +--------------------
 2 files changed, 9 insertions(+), 28 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 0bd286e..8648f1f 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1220,15 +1220,15 @@ int kvm_arch_init_vcpu(CPUState *cs)
     max_nested_state_len = kvm_max_nested_state_length();
     if (max_nested_state_len > 0) {
         assert(max_nested_state_len >= offsetof(struct kvm_nested_state, data));
-        env->nested_state = g_malloc0(max_nested_state_len);
 
-        env->nested_state->size = max_nested_state_len;
-
-        if (IS_INTEL_CPU(env)) {
-            struct kvm_vmx_nested_state_hdr *vmx_hdr =
-                &env->nested_state->hdr.vmx;
+        if (cpu_has_vmx(env)) {
+            struct kvm_vmx_nested_state_hdr *vmx_hdr;
 
+            env->nested_state = g_malloc0(max_nested_state_len);
+            env->nested_state->size = max_nested_state_len;
             env->nested_state->format = KVM_STATE_NESTED_FORMAT_VMX;
+
+            vmx_hdr = &env->nested_state->hdr.vmx;
             vmx_hdr->vmxon_pa = -1ull;
             vmx_hdr->vmcs12_pa = -1ull;
         }
@@ -2966,7 +2966,7 @@ static int kvm_put_nested_state(X86CPU *cpu)
     CPUX86State *env = &cpu->env;
     int max_nested_state_len = kvm_max_nested_state_length();
 
-    if (max_nested_state_len <= 0) {
+    if (!env->nested_state) {
         return 0;
     }
 
@@ -2980,7 +2980,7 @@ static int kvm_get_nested_state(X86CPU *cpu)
     int max_nested_state_len = kvm_max_nested_state_length();
     int ret;
 
-    if (max_nested_state_len <= 0) {
+    if (!env->nested_state) {
         return 0;
     }
 
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 8d90d98..fa8d1cc 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1004,31 +1004,13 @@ static const VMStateDescription vmstate_vmx_nested_state = {
     }
 };
 
-static bool svm_nested_state_needed(void *opaque)
-{
-    struct kvm_nested_state *nested_state = opaque;
-
-    return (nested_state->format == KVM_STATE_NESTED_FORMAT_SVM);
-}
-
-static const VMStateDescription vmstate_svm_nested_state = {
-    .name = "cpu/kvm_nested_state/svm",
-    .version_id = 1,
-    .minimum_version_id = 1,
-    .needed = svm_nested_state_needed,
-    .fields = (VMStateField[]) {
-        VMSTATE_END_OF_LIST()
-    }
-};
-
 static bool nested_state_needed(void *opaque)
 {
     X86CPU *cpu = opaque;
     CPUX86State *env = &cpu->env;
 
     return (env->nested_state &&
-            (vmx_nested_state_needed(env->nested_state) ||
-             svm_nested_state_needed(env->nested_state)));
+            vmx_nested_state_needed(env->nested_state));
 }
 
 static int nested_state_post_load(void *opaque, int version_id)
@@ -1090,7 +1072,6 @@ static const VMStateDescription vmstate_kvm_nested_state = {
     },
     .subsections = (const VMStateDescription*[]) {
         &vmstate_vmx_nested_state,
-        &vmstate_svm_nested_state,
         NULL
     }
 };
-- 
1.8.3.1