Re: [PATCH Part1 v5 13/38] x86/sev: Register GHCB memory when SEV-SNP is active

[Brijesh Singh]

On 8/23/21 12:35 PM, Borislav Petkov wrote:
> On Fri, Aug 20, 2021 at 10:19:08AM -0500, Brijesh Singh wrote:
> > The SEV-SNP guest is required to perform GHCB GPA registration. This is
> > because the hypervisor may prefer that a guest use a consistent and/or
> > specific GPA for the GHCB associated with a vCPU. For more information,
> > see the GHCB specification section GHCB GPA Registration.
> >
> > During the boot, init_ghcb() allocates a per-cpu GHCB page. On very first
> > VC exception, the exception handler switch to using the per-cpu GHCB page
> > allocated during the init_ghcb(). The GHCB page must be registered in
> > the current vcpu context.
> >
> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> > ---
> >   arch/x86/kernel/sev-internal.h | 12 ++++++++++++
> >   arch/x86/kernel/sev.c          | 28 ++++++++++++++++++++++++++++
> >   2 files changed, 40 insertions(+)
> >   create mode 100644 arch/x86/kernel/sev-internal.h
> >
> > diff --git a/arch/x86/kernel/sev-internal.h b/arch/x86/kernel/sev-internal.h
> > new file mode 100644
> > index 000000000000..0fb7324803b4
> > --- /dev/null
> > +++ b/arch/x86/kernel/sev-internal.h
> > @@ -0,0 +1,12 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Forward declarations for sev-shared.c
> > + *
> > + * Author: Brijesh Singh <brijesh.singh@xxxxxxx>
> > + */
> > +
> > +#ifndef __X86_SEV_INTERNAL_H__
> > +
> > +static void snp_register_ghcb_early(unsigned long paddr);
> > +
> > +#endif	/* __X86_SEV_INTERNAL_H__ */
>
> I believe you don't need that header if you move __sev_get_ghcb()
> and snp_register_ghcb() under the #include "sev-shared.c" so that
> snp_register_ghcb_early() is visible by then.

thanks, I will merge this in next version.