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Message-ID: <20240912190857.235849-14-david.kaplan@amd.com>
Date: Thu, 12 Sep 2024 14:08:36 -0500
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 13/34] x86/bugs: Restructure bhi mitigation
Restructure bhi mitigation to use select/apply functions to create
consistent vulnerability handling.
Define new AUTO mitigation for bhi.
Signed-off-by: David Kaplan <david.kaplan@....com>
---
arch/x86/kernel/cpu/bugs.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index eaef5a1cb4a3..da6ca2fc939d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -82,6 +82,8 @@ static void __init l1d_flush_select_mitigation(void);
static void __init srso_select_mitigation(void);
static void __init gds_select_mitigation(void);
static void __init gds_apply_mitigation(void);
+static void __init bhi_select_mitigation(void);
+static void __init bhi_apply_mitigation(void);
/* The base value of the SPEC_CTRL MSR without task-specific bits set */
u64 x86_spec_ctrl_base;
@@ -201,6 +203,7 @@ void __init cpu_select_mitigations(void)
*/
srso_select_mitigation();
gds_select_mitigation();
+ bhi_select_mitigation();
/*
* After mitigations are selected, some may need to update their
@@ -222,6 +225,7 @@ void __init cpu_select_mitigations(void)
rfds_apply_mitigation();
srbds_apply_mitigation();
gds_apply_mitigation();
+ bhi_apply_mitigation();
}
/*
@@ -1719,12 +1723,13 @@ static bool __init spec_ctrl_bhi_dis(void)
enum bhi_mitigations {
BHI_MITIGATION_OFF,
+ BHI_MITIGATION_AUTO,
BHI_MITIGATION_ON,
BHI_MITIGATION_VMEXIT_ONLY,
};
static enum bhi_mitigations bhi_mitigation __ro_after_init =
- IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
+ IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_AUTO : BHI_MITIGATION_OFF;
static int __init spectre_bhi_parse_cmdline(char *str)
{
@@ -1745,6 +1750,18 @@ static int __init spectre_bhi_parse_cmdline(char *str)
early_param("spectre_bhi", spectre_bhi_parse_cmdline);
static void __init bhi_select_mitigation(void)
+{
+ if (!boot_cpu_has(X86_BUG_BHI) || cpu_mitigations_off())
+ return;
+
+ if (bhi_mitigation == BHI_MITIGATION_OFF)
+ return;
+
+ if (bhi_mitigation == BHI_MITIGATION_AUTO)
+ bhi_mitigation = BHI_MITIGATION_ON;
+}
+
+static void __init bhi_apply_mitigation(void)
{
if (bhi_mitigation == BHI_MITIGATION_OFF)
return;
@@ -1876,9 +1893,6 @@ static void __init spectre_v2_select_mitigation(void)
mode == SPECTRE_V2_RETPOLINE)
spec_ctrl_disable_kernel_rrsba();
- if (boot_cpu_has(X86_BUG_BHI))
- bhi_select_mitigation();
-
spectre_v2_enabled = mode;
pr_info("%s\n", spectre_v2_strings[mode]);
--
2.34.1
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