Re: [PATCH 1/3] KVM: x86: hyper-v: don't crash on KVM_GET_SUPPORTED_HV_CPUID when kvm_intel.nested is disabled

From: Jim Mattson
Date: Tue Aug 27 2019 - 13:10:05 EST

On Tue, Aug 27, 2019 at 9:04 AM Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
> If kvm_intel is loaded with nested=0 parameter an attempt to perform
> KVM_GET_SUPPORTED_HV_CPUID results in OOPS as nested_get_evmcs_version hook
> in kvm_x86_ops is NULL (we assign it in nested_vmx_hardware_setup() and
> this only happens in case nested is enabled).
> Check that kvm_x86_ops->nested_get_evmcs_version is not NULL before
> calling it. With this, we can remove the stub from svm as it is no
> longer needed.
> Fixes: e2e871ab2f02 ("x86/kvm/hyper-v: Introduce nested_get_evmcs_version() helper")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>