lkml.org 
[lkml]   [2024]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 05/15] x86/sev: Use kernel provided SVSM Calling Areas
On Wed, May 08, 2024 at 02:13:17PM -0500, Tom Lendacky wrote:
> ok, maybe __perform_svsm_msr_protocol or such.

We'll bikeshed it in the coming weeks.

> There's quite a bit of interaction so I'll make sure to prefix everything.

Ack.

> The paravirt versions of local_irq_save and local_irq_restore can't be used
> as early as this routine is called.

tglx says you should do native_local_irq_save()/.._restore() helpers
just like the arch_local_irq_save()/..._restore() ones but use only
native_ functions without the paravirt gunk.

In a prepatch pls.

> > > + struct svsm_call call = {};
> > > + int ret;
> > > + u64 pa;
> > > +
> > > + /*
> > > + * Record the SVSM Calling Area address (CAA) if the guest is not
> > > + * running at VMPL0. The CA will be used to communicate with the
> > > + * SVSM to perform the SVSM services.
> > > + */
> > > + setup_svsm_ca(cc_info);
> > > +
> > > + /* Nothing to do if not running under an SVSM. */
> > > + if (!vmpl)
> > > + return;
> >
> > You set up stuff above and now you bail out?
>
> setup_svsm_ca() is what sets the vmpl variable. So nothing will have been
> setup if the VMPL is zero, in which case we don't continue on.

You still assign

/*
* The CA is identity mapped when this routine is called, both by the
* decompressor code and the early kernel code.
*/
boot_svsm_caa = (struct svsm_ca *)caa;
boot_svsm_caa_pa = caa;

regardless of vmpl.

I think you should assign those only when vmpl != 0.

Otherwise the code is confusing.

> > Judging by setup_svsm_ca() you don't really need that vmpl var but you
> > can check
> >
> > if (!boot_svsm_caa)
> > return;
> >
> > to determine whether a SVSM was detected.
>
> Yes, but the vmpl var will be used for attestation requests, sysfs, etc.

I guess that comes later in the patchset...

> > Huh, setup_svsm_ca() already assigned those...
>
> setup_svsm_ca() assigned the ones from the secrets page. The kernel now
> switches to using its own CA.

Comment pls.

Thx.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

\
 
 \ /
  Last update: 2024-05-08 21:59    [W:0.173 / U:0.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site