On Wed, Sep 23, 2020 at 12:10:25AM +0300, Maxim Levitsky wrote:
> This way we don't waste memory on VMs which don't use nesting
> virtualization even when the host enabled it for them.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> ---
> arch/x86/kvm/svm/nested.c | 42 ++++++++++++++++++++++++++++++
> arch/x86/kvm/svm/svm.c | 55 ++++++++++++++++++++++-----------------
> arch/x86/kvm/svm/svm.h | 6 +++++
> 3 files changed, 79 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 09417f5197410..dd13856818a03 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -467,6 +467,9 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
>
> vmcb12 = map.hva;
>
> + if (WARN_ON(!svm->nested.initialized))
Probably should use WARN_ON_ONCE, if this is somehow it, userspace could
easily spam the kernel.
Side topic, do we actually need 'initialized'? Wouldn't checking for a
valid nested.msrpm or nested.hsave suffice?
> + return 1;
> +
> if (!nested_vmcb_checks(svm, vmcb12)) {
> vmcb12->control.exit_code = SVM_EXIT_ERR;
> vmcb12->control.exit_code_hi = 0;
> @@ -684,6 +687,45 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> return 0;
> }
