On Fri, Apr 30, 2021 at 07:16:09AM -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.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 8c8c939a1754..e6819f170ec4 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -88,6 +88,13 @@ struct sev_es_runtime_data {
> * is currently unsupported in SEV-ES guests.
> */
> unsigned long dr7;
> +
> + /*
> + * SEV-SNP requires that the GHCB must be registered before using it.
> + * The flag below will indicate whether the GHCB is registered, if its
> + * not registered then sev_es_get_ghcb() will perform the registration.
> + */
> + bool snp_ghcb_registered;
> };
>
> struct ghcb_state {
> @@ -100,6 +107,9 @@ DEFINE_STATIC_KEY_FALSE(sev_es_enable_key);
> /* Needed in vc_early_forward_exception */
> void do_early_exception(struct pt_regs *regs, int trapnr);
>
> +/* Defined in sev-shared.c */
> +static void snp_register_ghcb(unsigned long paddr);
Can we get rid of those forward declarations pls? Due to sev-shared.c
this file is starting to spawn those and that's ugly.
Either through a code reorg or even defining a sev-internal.h header
which contains all those so that they don't pollute the code?
Thx.
> +
> static void __init setup_vc_stacks(int cpu)
> {
> struct sev_es_runtime_data *data;
> @@ -218,6 +228,12 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state)
> data->ghcb_active = true;
> }
>
> + /* SEV-SNP guest requires that GHCB must be registered before using it. */
> + if (sev_snp_active() && !data->snp_ghcb_registered) {
> + snp_register_ghcb(__pa(ghcb));
> + data->snp_ghcb_registered = true;
> + }
More missed review from last time:
"This needs to be set to true in the function itself, in the success
case."
Can you please be more careful and go through all review comments so
that I don't have to do the same work twice?
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
