linux-kernel - [PATCH RFC 2/7] x86: cpu: modify boot_command_line to saved_command

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Date:   Thu,  2 Jul 2020 18:18:22 +0300
From:   Mihai Carabas <mihai.carabas@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        Mihai Carabas <mihai.carabas@...cle.com>
Subject: [PATCH RFC 2/7] x86: cpu: modify boot_command_line to saved_command_line

as boot_command_line has the __initdata attribute and cannot be
used after booting the kernel. command_line evaluation needs to
be used on microcode late loading in order to enforce the proper
mitigations for different CPU bugs.

Signed-off-by: Mihai Carabas <mihai.carabas@...cle.com>
---
 arch/x86/kernel/cpu/bugs.c | 11 ++++++-----
 arch/x86/kernel/cpu/tsx.c  |  2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 7091947..1760598 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -684,7 +684,7 @@ static void spec_v2_user_print_cond(const char *reason, bool secure)
 		break;
 	}
 
-	ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
+	ret = cmdline_find_option(saved_command_line, "spectre_v2_user",
 				  arg, sizeof(arg));
 	if (ret < 0)
 		return SPECTRE_V2_USER_CMD_AUTO;
@@ -822,11 +822,12 @@ static enum spectre_v2_mitigation_cmd spectre_v2_parse_cmdline(void)
 	char arg[20];
 	int ret, i;
 
-	if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
+	if (cmdline_find_option_bool(saved_command_line, "nospectre_v2") ||
 	    cpu_mitigations_off())
 		return SPECTRE_V2_CMD_NONE;
 
-	ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
+	ret = cmdline_find_option(saved_command_line, "spectre_v2", arg,
+	    sizeof(arg));
 	if (ret < 0)
 		return SPECTRE_V2_CMD_AUTO;
 
@@ -1096,11 +1097,11 @@ static enum ssb_mitigation_cmd ssb_parse_cmdline(void)
 	char arg[20];
 	int ret, i;
 
-	if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
+	if (cmdline_find_option_bool(saved_command_line, "nospec_store_bypass_disable") ||
 	    cpu_mitigations_off()) {
 		return SPEC_STORE_BYPASS_CMD_NONE;
 	} else {
-		ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
+		ret = cmdline_find_option(saved_command_line, "spec_store_bypass_disable",
 					  arg, sizeof(arg));
 		if (ret < 0)
 			return SPEC_STORE_BYPASS_CMD_AUTO;
diff --git a/arch/x86/kernel/cpu/tsx.c b/arch/x86/kernel/cpu/tsx.c
index 7c46581..436fa93 100644
--- a/arch/x86/kernel/cpu/tsx.c
+++ b/arch/x86/kernel/cpu/tsx.c
@@ -92,7 +92,7 @@ void tsx_init(void)
 	if (!tsx_ctrl_is_supported())
 		return;
 
-	ret = cmdline_find_option(boot_command_line, "tsx", arg, sizeof(arg));
+	ret = cmdline_find_option(saved_command_line, "tsx", arg, sizeof(arg));
 	if (ret >= 0) {
 		if (!strcmp(arg, "on")) {
 			tsx_ctrl_state = TSX_CTRL_ENABLE;
-- 
1.8.3.1