Restructure ssb to use select/apply functions to create consistent
vulnerability handling.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
 arch/x86/kernel/cpu/bugs.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 32ebe9e934fe..c996c1521851 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -65,6 +65,7 @@ static void __init spectre_v2_user_select_mitigation(void);
 static void __init spectre_v2_user_update_mitigation(void);
 static void __init spectre_v2_user_apply_mitigation(void);
 static void __init ssb_select_mitigation(void);
+static void __init ssb_apply_mitigation(void);
 static void __init l1tf_select_mitigation(void);
 static void __init mds_select_mitigation(void);
 static void __init mds_update_mitigation(void);
@@ -223,6 +224,7 @@ void __init cpu_select_mitigations(void)
 	spectre_v2_apply_mitigation();
 	retbleed_apply_mitigation();
 	spectre_v2_user_apply_mitigation();
+	ssb_apply_mitigation();
 	mds_apply_mitigation();
 	taa_apply_mitigation();
 	mmio_apply_mitigation();
@@ -2211,13 +2213,26 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
 		break;
 	}
 
+	return mode;
+}
+
+static void ssb_select_mitigation(void)
+{
+	ssb_mode = __ssb_select_mitigation();
+
+	if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+		pr_info("%s\n", ssb_strings[ssb_mode]);
+}
+
+static void __init ssb_apply_mitigation(void)
+{
 	/*
 	 * We have three CPU feature flags that are in play here:
 	 *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
 	 *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
 	 *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
 	 */
-	if (mode == SPEC_STORE_BYPASS_DISABLE) {
+	if (ssb_mode == SPEC_STORE_BYPASS_DISABLE) {
 		setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
 		/*
 		 * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
@@ -2232,15 +2247,6 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
 		}
 	}
 
-	return mode;
-}
-
-static void ssb_select_mitigation(void)
-{
-	ssb_mode = __ssb_select_mitigation();
-
-	if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
-		pr_info("%s\n", ssb_strings[ssb_mode]);
 }
 
 #undef pr_fmt
-- 
2.34.1

On 12.09.24 г. 22:08 ч., David Kaplan wrote:
> Restructure ssb to use select/apply functions to create consistent
> vulnerability handling.
> 
> Signed-off-by: David Kaplan <david.kaplan@amd.com>
> ---
>   arch/x86/kernel/cpu/bugs.c | 26 ++++++++++++++++----------
>   1 file changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index 32ebe9e934fe..c996c1521851 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -65,6 +65,7 @@ static void __init spectre_v2_user_select_mitigation(void);
>   static void __init spectre_v2_user_update_mitigation(void);
>   static void __init spectre_v2_user_apply_mitigation(void);
>   static void __init ssb_select_mitigation(void);
> +static void __init ssb_apply_mitigation(void);
>   static void __init l1tf_select_mitigation(void);
>   static void __init mds_select_mitigation(void);
>   static void __init mds_update_mitigation(void);
> @@ -223,6 +224,7 @@ void __init cpu_select_mitigations(void)
>   	spectre_v2_apply_mitigation();
>   	retbleed_apply_mitigation();
>   	spectre_v2_user_apply_mitigation();
> +	ssb_apply_mitigation();
>   	mds_apply_mitigation();
>   	taa_apply_mitigation();
>   	mmio_apply_mitigation();
> @@ -2211,13 +2213,26 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void)
>   		break;
>   	}
>   
> +	return mode;
> +}
> +
> +static void ssb_select_mitigation(void)
> +{
> +	ssb_mode = __ssb_select_mitigation();
> +
> +	if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
> +		pr_info("%s\n", ssb_strings[ssb_mode]);
> +}

nit: While at it simply open code __ssb_select_mitigation() here.

<snip>