Re: [RFC PATCH v5 086/104] KVM: TDX: handle ept violation/misconfig exit

[Xiaoyao Li]

On 4/7/2022 4:50 AM, Sagi Shahar wrote:
> On Fri, Mar 4, 2022 at 12:23 PM <isaku.yamahata@xxxxxxxxx> wrote:
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> >
> > On EPT violation, call a common function, __vmx_handle_ept_violation() to
> > trigger x86 MMU code.  On EPT misconfiguration, exit to ring 3 with
> > KVM_EXIT_UNKNOWN.  because EPT misconfiguration can't happen as MMIO is
> > trigged by TDG.VP.VMCALL. No point to set a misconfiguration value for the
> > fast path.
> >
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > ---
> >   arch/x86/kvm/vmx/tdx.c | 40 ++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 38 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index 6fbe89bcfe1e..2c35dcad077e 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -1081,6 +1081,40 @@ void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
> >          __vmx_deliver_posted_interrupt(vcpu, &tdx->pi_desc, vector);
> >   }
> >
> > +#define TDX_SEPT_PFERR (PFERR_WRITE_MASK | PFERR_USER_MASK)
>
> TDX_SEPT_PFERR is defined using PFERR_.* bitmask but
> __vmx_handle_ept_violation is accepting an EPT_VIOLATION_.* bitmask.
> so (PFERR_WRITE_MASK | PFERR_USER_MASK) will get interpreted as
> (EPT_VIOLATION_ACC_WRITE | EPT_VIOLATION_ACC_INSTR) which will get
> translated to (PFERR_WRITE_MASK | PFERR_FETCH_MASK). Was that the
> intention of this code?

No. It's a mistake. We have corrected internally you can find corrected 
code in github repo or see it in next version.