Re: [PATCH v10 098/108] KVM: TDX: Implement callbacks for MSR operations for TDX

Isaku Yamahata
2023-01-12T10:11:37Z

On Wed, Jan 04, 2023 at 01:20:13PM -0800,
Ackerley Tng <ackerleytng@google.com> wrote:

>
> I believe we should also have a handler for .msr_filter_changed.
>
> Without an .msr_filter_changed handler, a host crash can occur if we
> first set up a vcpu for the TD, and then set an MSR filter.
>
> If we first set up a vcpu for the TD, and then set an MSR filter, upon
> vcpu_enter_guest, the .msr_filter_changed handler (currently
> vmx_msr_filter_changed()) will be invoked. to_vmx(vcpu) interprets the
> containing struct of struct kvm_vcpu to be a struct vcpu_vmx instead of
> a struct vcpu_tdx.
>
> In my case, I was working on a selftest and the missing handler caused a
> NULL dereference in vmx_disable_intercept_for_msr() because
> vmx->vmcs01.msr_bitmap is NULL.

Nice catch. I'll fix it.
--
Isaku Yamahata <isaku.yamahata@gmail.com>