On Tue, Aug 26, 2025 at 4:22 AM Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx> wrote:
>
>
>
> On 8/21/2025 12:29 PM, Sagi Shahar wrote:
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> >
> > This also exercises the KVM_TDX_CAPABILITIES ioctl.
>
> That commit message should describe what the patch does instead of relying on
> the title/short log.
>
> >
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > Co-developed-by: Sagi Shahar <sagis@xxxxxxxxxx>
> > Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
> > ---
> > .../selftests/kvm/lib/x86/tdx/tdx_util.c | 17 +++++++++++++++++
> > 1 file changed, 17 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > index 3869756a5641..d8eab99d9333 100644
> > --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> > @@ -232,6 +232,21 @@ static void vm_tdx_filter_cpuid(struct kvm_vm *vm,
> > free(tdx_cap);
> > }
> >
> > +static void tdx_check_attributes(struct kvm_vm *vm, uint64_t attributes)
> > +{
> > + struct kvm_tdx_capabilities *tdx_cap;
> > +
> > + tdx_cap = tdx_read_capabilities(vm);
> > +
> > + /* TDX spec: any bits 0 in supported_attrs must be 0 in attributes */
> > + TEST_ASSERT_EQ(attributes & ~tdx_cap->supported_attrs, 0);
> > +
> > + /* TDX spec: any bits 1 in attributes must be 1 in supported_attrs */
>
> The comments are not accurate.
>
> The descriptions in TDX spec are for ATTRIBUTES_ FIXED0 and ATTRIBUTES_ FIXED1.
> They are related to tdx_cap->supported_attrs returned by KVM, but they are not
> the same.
>
I actually think that one of the conditions is redundant. Here's my reasoning:
If a bit is 0 in attributes then both conditions will be true
regardless of the value of supported_attrs.
If a bit is 1 in attributes then both conditions will be true iff the
corresponding bit in supported_attrs is 1.
I'm going to keep only the second condition which is clearer and
update the comment.
>
> > + TEST_ASSERT_EQ(attributes & tdx_cap->supported_attrs, attributes);
> > +
> > + free(tdx_cap);
> > +}
> > +
> > void vm_tdx_init_vm(struct kvm_vm *vm, uint64_t attributes)
> > {
> > struct kvm_tdx_init_vm *init_vm;
> > @@ -251,6 +266,8 @@ void vm_tdx_init_vm(struct kvm_vm *vm, uint64_t attributes)
> > memcpy(&init_vm->cpuid, cpuid, kvm_cpuid2_size(cpuid->nent));
> > free(cpuid);
> >
> > + tdx_check_attributes(vm, attributes);
> > +
> > init_vm->attributes = attributes;
> >
> > vm_tdx_vm_ioctl(vm, KVM_TDX_INIT_VM, 0, init_vm);
>
