On 23.07.20 16:27, Vitaly Kuznetsov wrote:
> HF2_GIF_MASK is set in env->hflags2 unconditionally on CPU reset
> (see x86_cpu_reset()) but when calling KVM_SET_NESTED_STATE,
> KVM_STATE_NESTED_GIF_SET is only valid for nSVM as e.g. nVMX code
> looks like
>
> if (kvm_state->hdr.vmx.vmxon_pa == -1ull) {
> if (kvm_state->flags & ~KVM_STATE_NESTED_EVMCS)
> return -EINVAL;
> }
>
> Also, when adjusting the environment after KVM_GET_NESTED_STATE we
> need not reset HF2_GIF_MASK on VMX as e.g. x86_cpu_pending_interrupt()
> expects it to be set.
>
> Alternatively, we could've made env->hflags2 SVM-only.
>
> Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
> Fixes: b16c0e20c742 ("KVM: add support for AMD nested live migration")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> target/i386/kvm.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 2b6b7443d273..3c4647fbfbf6 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -3883,7 +3883,9 @@ static int kvm_put_nested_state(X86CPU *cpu)
> } else {
> env->nested_state->flags &= ~KVM_STATE_NESTED_GUEST_MODE;
> }
> - if (env->hflags2 & HF2_GIF_MASK) {
> +
> + /* Don't set KVM_STATE_NESTED_GIF_SET on VMX as it is illegal */
> + if (cpu_has_svm(env) && (env->hflags2 & HF2_GIF_MASK)) {
> env->nested_state->flags |= KVM_STATE_NESTED_GIF_SET;
> } else {
> env->nested_state->flags &= ~KVM_STATE_NESTED_GIF_SET;
> @@ -3925,10 +3927,14 @@ static int kvm_get_nested_state(X86CPU *cpu)
> } else {
> env->hflags &= ~HF_GUEST_MASK;
> }
> - if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) {
> - env->hflags2 |= HF2_GIF_MASK;
> - } else {
> - env->hflags2 &= ~HF2_GIF_MASK;
> +
> + /* Keep HF2_GIF_MASK set on !SVM as x86_cpu_pending_interrupt() needs it */
> + if (cpu_has_svm(env)) {
> + if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) {
> + env->hflags2 |= HF2_GIF_MASK;
> + } else {
> + env->hflags2 &= ~HF2_GIF_MASK;
> + }
> }
>
> return ret;
>
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
Thanks!
Jan
--
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