Re: [PATCH v2 18/58] i386/tdx: Validate TD attributes

[Xiaoyao Li]

On 8/21/2023 5:16 PM, Daniel P. Berrangé wrote:
> On Fri, Aug 18, 2023 at 05:50:01AM -0400, Xiaoyao Li wrote:
> > Validate TD attributes with tdx_caps that fixed-0 bits must be zero and
> > fixed-1 bits must be set.
> >
> > Besides, sanity check the attribute bits that have not been supported by
> > QEMU yet. e.g., debug bit, it will be allowed in the future when debug
> > TD support lands in QEMU.
> >
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> > Acked-by: Gerd Hoffmann <kraxel@redhat.com>
> > ---
> >   target/i386/kvm/tdx.c | 27 +++++++++++++++++++++++++--
> >   1 file changed, 25 insertions(+), 2 deletions(-)
> >
> > diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> > index 629abd267da8..73da15377ec3 100644
> > --- a/target/i386/kvm/tdx.c
> > +++ b/target/i386/kvm/tdx.c
> > @@ -32,6 +32,7 @@
> >                                        (1U << KVM_FEATURE_PV_SCHED_YIELD) | \
> >                                        (1U << KVM_FEATURE_MSI_EXT_DEST_ID))
> >   
> > +#define TDX_TD_ATTRIBUTES_DEBUG             BIT_ULL(0)
> >   #define TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE   BIT_ULL(28)
> >   #define TDX_TD_ATTRIBUTES_PKS               BIT_ULL(30)
> >   #define TDX_TD_ATTRIBUTES_PERFMON           BIT_ULL(63)
> > @@ -462,13 +463,32 @@ int tdx_kvm_init(MachineState *ms, Error **errp)
> >       return 0;
> >   }
> >   
> > -static void setup_td_guest_attributes(X86CPU *x86cpu)
> > +static int tdx_validate_attributes(TdxGuest *tdx)
> > +{
> > +    if (((tdx->attributes & tdx_caps->attrs_fixed0) | tdx_caps->attrs_fixed1) 
> > !=
> > +        tdx->attributes) {
> > +            error_report("Invalid attributes 0x%lx for TDX VM (fixed0 0x%llx, 
> > fixed1 0x%llx)",
> > +                          tdx->attributes, tdx_caps->attrs_fixed0, 
> > tdx_caps->attrs_fixed1);
> > +            return -EINVAL;
> > +    }
> > +
> > +    if (tdx->attributes & TDX_TD_ATTRIBUTES_DEBUG) {
> > +        error_report("Current QEMU doesn't support attributes.debug[bit 0] for TDX 
> > VM");
> > +        return -EINVAL;
> > +    }
>
> Use error_setg() in both cases, passing in a 'Error **errp' object,
> and 'return -1' instead of returning an errno value.

Will do it in next version.

thanks!

> > +
> > +    return 0;
> > +}
> > +
> > +static int setup_td_guest_attributes(X86CPU *x86cpu)
> >   {
> >       CPUX86State *env = &x86cpu->env;
> >   
> >       tdx_guest->attributes |= (env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS) ?
> >                                TDX_TD_ATTRIBUTES_PKS : 0;
> >       tdx_guest->attributes |= x86cpu->enable_pmu ? TDX_TD_ATTRIBUTES_PERFMON : 
> > 0;
> > +
> > +    return tdx_validate_attributes(tdx_guest);
>
> Pass along "errp" into this
>
> >   }
> >   
> >   int tdx_pre_create_vcpu(CPUState *cpu)
> > @@ -493,7 +513,10 @@ int tdx_pre_create_vcpu(CPUState *cpu)
>
> In an earlier patch I suggested adding 'Error **errp' to this method...
>
> >           goto out_free;
> >       }
> >   
> > -    setup_td_guest_attributes(x86cpu);
> > +    r = setup_td_guest_attributes(x86cpu);
>
> ...it can also be passed into this method
>
> > +    if (r) {
> > +        goto out;
> > +    }
> >   
> >       init_vm->cpuid.nent = kvm_x86_arch_cpuid(env, init_vm->cpuid.entries, 0);
> >       init_vm->attributes = tdx_guest->attributes;
> > --
> > 2.34.1
>
> With regards,
> Daniel