linux-kernel - [RFC PATCH 52/56] x86/bugs: Support parsing mitigation options

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Message-ID: <20251013143444.3999-53-david.kaplan@amd.com>
Date: Mon, 13 Oct 2025 09:34:40 -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: Alexander Graf <graf@...zon.com>, Boris Ostrovsky
	<boris.ostrovsky@...cle.com>, <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 52/56] x86/bugs: Support parsing mitigation options

Add arch-specific function for determining if an option is related to a
mitigation and parsing it.  These will be used for parsing a string of
options for re-evaluating cpu mitigations.

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/include/asm/bugs.h |  2 ++
 arch/x86/kernel/cpu/bugs.c  | 56 +++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/arch/x86/include/asm/bugs.h b/arch/x86/include/asm/bugs.h
index 2e1a7d282e51..1e142a676335 100644
--- a/arch/x86/include/asm/bugs.h
+++ b/arch/x86/include/asm/bugs.h
@@ -13,5 +13,7 @@ static inline int ppro_with_ram_bug(void) { return 0; }
 extern void cpu_bugs_smt_update(void);
 void arch_cpu_reset_mitigations(void);
 void cpu_bugs_update_speculation_msrs(void);
+bool arch_is_mitigation_opt(char *param);
+int arch_parse_mitigation_opt(char *param, char *val);
 
 #endif /* _ASM_X86_BUGS_H */
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 2f82261d033d..26ceb42e0cfb 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -3991,6 +3991,62 @@ void __warn_thunk(void)
 }
 
 #ifdef CONFIG_DYNAMIC_MITIGATIONS
+struct mitigation_info {
+	char *param;
+	int (*parse)(char *str);
+};
+
+static struct mitigation_info mitigation_parsers[] = {
+	{"mds", mds_cmdline},
+	{"tsx_async_abort", tsx_async_abort_parse_cmdline},
+	{"mmio_stale_data", mmio_stale_data_parse_cmdline},
+	{"reg_file_data_sampling", rfds_parse_cmdline},
+	{"srbds", srbds_parse_cmdline},
+	{"gather_data_sampling", gds_parse_cmdline},
+	{"nospectre_v1", nospectre_v1_cmdline},
+	{"retbleed", retbleed_parse_cmdline},
+	{"indirect_target_selection", its_parse_cmdline},
+	{"spectre_v2_user", spectre_v2_user_parse_cmdline},
+	{"nospectre_v2", nospectre_v2_parse_cmdline},
+	{"spectre_v2", spectre_v2_parse_cmdline},
+	{"spectre_bhi", spectre_bhi_parse_cmdline},
+	{"nospec_store_bypass_disable", nossb_parse_cmdline},
+	{"spec_store_bypass_disable", ssb_parse_cmdline},
+	{"l1tf", l1tf_cmdline},
+	{"spec_rstack_overflow", srso_parse_cmdline},
+	{"tsa", tsa_parse_cmdline},
+	{"vmscape", vmscape_parse_cmdline}
+};
+
+static struct mitigation_info *get_mitigation_info(char *param)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(mitigation_parsers); i++) {
+		if (parameq(param, mitigation_parsers[i].param))
+			return &mitigation_parsers[i];
+	}
+
+	return NULL;
+}
+
+bool arch_is_mitigation_opt(char *param)
+{
+	return get_mitigation_info(param);
+}
+
+int arch_parse_mitigation_opt(char *param, char *val)
+{
+	struct mitigation_info *info = get_mitigation_info(param);
+
+	if (!info) {
+		pr_warn("Ignoring non-mitigation option %s\n", param);
+		return 0;
+	}
+
+	return info->parse(val);
+}
+
 void arch_cpu_reset_mitigations(void)
 {
 	spectre_v1_reset_mitigation();
-- 
2.34.1