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

[Borislav Petkov]

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.

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