linux-kernel - [RFC PATCH 07/34] x86/bugs: Remove md_clear_*

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Message-ID: <20240912190857.235849-8-david.kaplan@amd.com>
Date: Thu, 12 Sep 2024 14:08:30 -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 07/34] x86/bugs: Remove md_clear_*_mitigation()

The functionality in md_clear_update_mitigation() and
md_clear_select_mitigation() is now integrated into the select/update
functions for the MDS, TAA, MMIO, and RFDS vulnerabilities.

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/kernel/cpu/bugs.c | 65 --------------------------------------
 1 file changed, 65 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d3e6ce7238e4..df41572c5d10 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -62,8 +62,6 @@ static void __init l1tf_select_mitigation(void);
 static void __init mds_select_mitigation(void);
 static void __init mds_update_mitigation(void);
 static void __init mds_apply_mitigation(void);
-static void __init md_clear_update_mitigation(void);
-static void __init md_clear_select_mitigation(void);
 static void __init taa_select_mitigation(void);
 static void __init taa_update_mitigation(void);
 static void __init taa_apply_mitigation(void);
@@ -197,7 +195,6 @@ void __init cpu_select_mitigations(void)
 	taa_select_mitigation();
 	mmio_select_mitigation();
 	rfds_select_mitigation();
-	md_clear_select_mitigation();
 	srbds_select_mitigation();
 	l1d_flush_select_mitigation();
 
@@ -661,68 +658,6 @@ static __init int rfds_parse_cmdline(char *str)
 }
 early_param("reg_file_data_sampling", rfds_parse_cmdline);
 
-#undef pr_fmt
-#define pr_fmt(fmt)     "" fmt
-
-static void __init md_clear_update_mitigation(void)
-{
-	if (cpu_mitigations_off())
-		return;
-
-	if (!boot_cpu_has(X86_FEATURE_CLEAR_CPU_BUF))
-		goto out;
-
-	/*
-	 * X86_FEATURE_CLEAR_CPU_BUF is now enabled. Update MDS, TAA and MMIO
-	 * Stale Data mitigation, if necessary.
-	 */
-	if (mds_mitigation == MDS_MITIGATION_OFF &&
-	    boot_cpu_has_bug(X86_BUG_MDS)) {
-		mds_mitigation = MDS_MITIGATION_FULL;
-		mds_select_mitigation();
-	}
-	if (taa_mitigation == TAA_MITIGATION_OFF &&
-	    boot_cpu_has_bug(X86_BUG_TAA)) {
-		taa_mitigation = TAA_MITIGATION_VERW;
-		taa_select_mitigation();
-	}
-	/*
-	 * MMIO_MITIGATION_OFF is not checked here so that mmio_stale_data_clear
-	 * gets updated correctly as per X86_FEATURE_CLEAR_CPU_BUF state.
-	 */
-	if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) {
-		mmio_mitigation = MMIO_MITIGATION_VERW;
-		mmio_select_mitigation();
-	}
-	if (rfds_mitigation == RFDS_MITIGATION_OFF &&
-	    boot_cpu_has_bug(X86_BUG_RFDS)) {
-		rfds_mitigation = RFDS_MITIGATION_VERW;
-		rfds_select_mitigation();
-	}
-out:
-	if (boot_cpu_has_bug(X86_BUG_MDS))
-		pr_info("MDS: %s\n", mds_strings[mds_mitigation]);
-	if (boot_cpu_has_bug(X86_BUG_TAA))
-		pr_info("TAA: %s\n", taa_strings[taa_mitigation]);
-	if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
-		pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]);
-	else if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
-		pr_info("MMIO Stale Data: Unknown: No mitigations\n");
-	if (boot_cpu_has_bug(X86_BUG_RFDS))
-		pr_info("Register File Data Sampling: %s\n", rfds_strings[rfds_mitigation]);
-}
-
-static void __init md_clear_select_mitigation(void)
-{
-
-	/*
-	 * As these mitigations are inter-related and rely on VERW instruction
-	 * to clear the microarchitural buffers, update and print their status
-	 * after mitigation selection is done for each of these vulnerabilities.
-	 */
-	md_clear_update_mitigation();
-}
-
 #undef pr_fmt
 #define pr_fmt(fmt)	"SRBDS: " fmt
 
-- 
2.34.1