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Re: [Qemu-devel] [PATCH 1/4] target/i386: kvm: Init nested-state for VMX
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 1/4] target/i386: kvm: Init nested-state for VMX when vCPU expose VMX |
Date: |
Thu, 11 Jul 2019 15:45:12 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 |
On 05/07/19 23:06, Liran Alon wrote:
> - if (IS_INTEL_CPU(env)) {
> + if (cpu_has_vmx(env)) {
> struct kvm_vmx_nested_state_hdr *vmx_hdr =
> &env->nested_state->hdr.vmx;
>
I am not sure this is enough, because kvm_get_nested_state and
kvm_put_nested_state would run anyway later. If we want to cull them
completely for a non-VMX virtual machine, I'd do something like this:
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 5035092..73ab102 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1748,14 +1748,13 @@ 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)) {
+ if (cpu_has_vmx(env)) {
struct kvm_vmx_nested_state_hdr *vmx_hdr =
&env->nested_state->hdr.vmx;
+ 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->vmxon_pa = -1ull;
vmx_hdr->vmcs12_pa = -1ull;
@@ -3682,7 +3681,7 @@ 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;
}
@@ -3696,7 +3695,7 @@ 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;
}
What do you think? (As a side effect, this completely disables
KVM_GET/SET_NESTED_STATE on SVM, which I think is safer since it
will have to save at least the NPT root and the paging mode. So we
could remove vmstate_svm_nested_state as well).
Paolo