Re: [PATCH v19 030/130] KVM: TDX: Add helper functions to print TDX SEAMCALL error

Huang, Kai
2024-03-22T04:37:48Z

On Thu, 2024-03-21 at 16:52 -0700, Isaku Yamahata wrote:
> On Thu, Mar 21, 2024 at 12:09:57PM +1300,
> "Huang, Kai" <kai.huang@intel.com> wrote:
>
> > > Does it make sense?
> > >
> > > void pr_tdx_error(u64 op, u64 error_code)
> > > {
> > > pr_err_ratelimited("SEAMCALL (0x%016llx) failed: 0x%016llx\n",
> > > op, error_code);
> > > }
> >
> > Should we also have a _ret version?
> >
> > void pr_seamcall_err(u64 op, u64 err)
> > {
> > /* A comment to explain why using the _ratelimited() version? */
>
> Because KVM can hit successive seamcall erorrs e.g. during desutructing TD,
> (it's unintentional sometimes), ratelimited version is preferred as safe guard.
> For example, SEAMCALL on all or some LPs (TDH_MNG_KEY_FREEID) can fail at the
> same time. And the number of LPs can be hundreds.

I mean you certainly have a reason to use _ratelimited() version. My point is
you at least explain it in a comment.

>
>
> > pr_err_ratelimited(...);
> > }
> >
> > void pr_seamcall_err_ret(u64 op, u64 err, struct tdx_module_args *arg)
> > {
> > pr_err_seamcall(op, err);
> >
> > pr_err_ratelimited(...);
> > }
> >
> > (Hmm... if you look at the tdx.c in TDX host, there's similar code there,
> > and again, it was a little bit annoying when I did that..)
> >
> > Again, if we just use seamcall_ret() for ALL SEAMCALLs except VP.ENTER, we
> > can simply have one..
>
> What about this?
>
> void pr_seamcall_err_ret(u64 op, u64 err, struct tdx_module_args *arg)
> {
> pr_err_ratelimited("SEAMCALL (0x%016llx) failed: 0x%016llx\n",
> op, error_code);
> if (arg)
> pr_err_ratelimited(...);
> }
>

Fine to me.

Or call pr_seamcall_err() instead. I don't care too much.