Re: [PATCH v8 11/40] x86/sev: Register GHCB memory when SEV-SNP is active

Borislav Petkov
2021-12-22T13:16:45Z

On Fri, Dec 10, 2021 at 09:43:03AM -0600, Brijesh Singh wrote:
> @@ -652,7 +652,7 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
> * This function runs on the first #VC exception after the kernel
> * switched to virtual addresses.
> */
> -static bool __init sev_es_setup_ghcb(void)
> +static bool __init setup_ghcb(void)
> {
> /* First make sure the hypervisor talks a supported protocol. */
> if (!sev_es_negotiate_protocol())

Ok, let me stare at this for a while:

This gets called by handle_vc_boot_ghcb() which gets set at build time:

arch/x86/kernel/head_64.S:372:SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)

initial_vc_handler() gets called by vc_boot_ghcb() which gets set in

early_setup_idt()

and that function already does sev_snp_register_ghcb().

So why don't you concentrate the work setup_ghcb() does before the first
#VC and call it in early_setup_idt(), before the IDT is set?

And then you get rid of yet another setup-at-first-use case?

Thx.

--
Regards/Gruss,
Boris.