Re: [PATCH v2 09/12] x86/sev: Use AP Jump Table blob to stop CPU

Borislav Petkov
2021-11-15T18:44:29Z

On Mon, Sep 13, 2021 at 05:56:00PM +0200, Joerg Roedel wrote:
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index 134a7c9d91b6..cd14b6e10f12 100644
> --- a/arch/x86/include/asm/sev.h
> +++ b/arch/x86/include/asm/sev.h
> @@ -81,12 +81,19 @@ static __always_inline void sev_es_nmi_complete(void)
> __sev_es_nmi_complete();
> }
> extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
> +void __sev_es_stop_this_cpu(void);
> +static __always_inline void sev_es_stop_this_cpu(void)

What's that for?

IOW, the below seems to build too:

---
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 1f16fc907636..398105580862 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -87,12 +87,7 @@ extern enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
struct es_em_ctxt *ctxt,
u64 exit_code, u64 exit_info_1,
u64 exit_info_2);
-void __sev_es_stop_this_cpu(void);
-static __always_inline void sev_es_stop_this_cpu(void)
-{
- if (static_branch_unlikely(&sev_es_enable_key))
- __sev_es_stop_this_cpu();
-}
+void sev_es_stop_this_cpu(void);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 39378357dc5a..7a74b3273f1a 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -694,8 +694,11 @@ void __noreturn sev_jumptable_ap_park(void)
}
STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park);

-void __sev_es_stop_this_cpu(void)
+void sev_es_stop_this_cpu(void)
{
+ if (!static_branch_unlikely(&sev_es_enable_key))
+ return;
+
/* Only park in the AP Jump Table when the code has been installed */
if (!sev_ap_jumptable_blob_installed)
return;

---

And as previously mentioned s/sev_es/sev/ if those are going to be used
on SNP guests too.

--
Regards/Gruss,
Boris.