On Tue, 2022-11-22 at 11:14 -0800, Dave Hansen wrote:
> On 11/20/22 16:26, Kai Huang wrote:
> > The first step of initializing the module is to call TDH.SYS.INIT once
> > on any logical cpu to do module global initialization. Do the module
> > global initialization.
> >
> > It also detects the TDX module, as seamcall() returns -ENODEV when the
> > module is not loaded.
>
> Part of making a good patch set is telling a bit of a story. In patch
> 4, you laid out 6 steps necessary to initialize TDX. On top of that,
> there is infrastructure It would be great to lay that out in a way that
> folks can actually follow along.
>
> For instance, it would be great to tell the reader here that this patch
> is an inflection point. It is transitioning out of the infrastructure
> (patches 1->6) and into the actual "multi-steps" of initialization that
> the module spec requires.
>
> This patch is *TOTALLY* different from the one before it because it
> actually _starts_ to do something useful.
>
> But, you wouldn't know it from the changelog.
I'll try to enhance the changelog to make them more connected. Right now I
don't have a clear clue on how to write in best way.
>
> > arch/x86/virt/vmx/tdx/tdx.c | 19 +++++++++++++++++--
> > arch/x86/virt/vmx/tdx/tdx.h | 1 +
> > 2 files changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> > index 5db1a05cb4bd..f292292313bd 100644
> > --- a/arch/x86/virt/vmx/tdx/tdx.c
> > +++ b/arch/x86/virt/vmx/tdx/tdx.c
> > @@ -208,8 +208,23 @@ static void seamcall_on_each_cpu(struct seamcall_ctx *sc)
> > */
> > static int init_tdx_module(void)
> > {
> > - /* The TDX module hasn't been detected */
> > - return -ENODEV;
> > + int ret;
> > +
> > + /*
> > + * Call TDH.SYS.INIT to do the global initialization of
> > + * the TDX module. It also detects the module.
> > + */
> > + ret = seamcall(TDH_SYS_INIT, 0, 0, 0, 0, NULL, NULL);
> > + if (ret)
> > + goto out;
>
> Please also note that the 0's are all just unused parameters. They mean
> nothing.
Will add to the comment.
>
> > +
> > + /*
> > + * Return -EINVAL until all steps of TDX module initialization
> > + * process are done.
> > + */
> > + ret = -EINVAL;
> > +out:
> > + return ret;
> > }
>
> It might be a bit unconventional, but can you imagine how well it would
> tell the story if this comment said:
>
> /*
> * TODO:
> * - Logical-CPU scope initialization (TDH_SYS_INIT_LP)
> * - Enumerate capabilities and platform configuration
> (TDH_SYS_CONFIG)
> ...
> */
>
> and then each of the following patches that *did* those things removed
> the TODO line from the list.
>
> That TODO list could have been added in patch 4.
>
Thanks for suggestion. Will do.
I think I can do this to "construct TDMRs" related patches too.
