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Message-ID: <20241015105107.496105-3-leitao@debian.org>
Date: Tue, 15 Oct 2024 03:51:06 -0700
From: Breno Leitao <leitao@...ian.org>
To: bp@...en8.de,
x86@...nel.org,
Thomas Gleixner <tglx@...utronix.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>,
"H. Peter Anvin" <hpa@...or.com>
Cc: kernel-team@...a.com,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] x86/bugs: spectre user default must depend on MITIGATION_SPECTRE_V2
Change the default value of spectre v2 in user mode to respect the
CONFIG_MITIGATION_SPECTRE_V2 config option.
Currently, user mode spectre v2 is set to auto
(SPECTRE_V2_USER_CMD_AUTO) by default, even if
CONFIG_MITIGATION_SPECTRE_V2 is disabled.
Set the spectre_v2 value to auto (SPECTRE_V2_USER_CMD_AUTO) if the
Spectre v2 config (CONFIG_MITIGATION_SPECTRE_V2) is enabled, otherwise
set the value to none (SPECTRE_V2_USER_CMD_NONE).
Important to say the command line argument "spectre_v2_user" overwrites
the default value in both cases.
Signed-off-by: Breno Leitao <leitao@...ian.org>
Acked-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
arch/x86/kernel/cpu/bugs.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 6d3b61d7be9c..c21ff072e048 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1277,9 +1277,13 @@ static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd;
static enum spectre_v2_user_cmd __init
spectre_v2_parse_user_cmdline(void)
{
+ enum spectre_v2_user_cmd mode;
char arg[20];
int ret, i;
+ mode = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ?
+ SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE;
+
switch (spectre_v2_cmd) {
case SPECTRE_V2_CMD_NONE:
return SPECTRE_V2_USER_CMD_NONE;
@@ -1292,7 +1296,7 @@ spectre_v2_parse_user_cmdline(void)
ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
arg, sizeof(arg));
if (ret < 0)
- return SPECTRE_V2_USER_CMD_AUTO;
+ return mode;
for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
if (match_option(arg, ret, v2_user_options[i].option)) {
@@ -1302,8 +1306,8 @@ spectre_v2_parse_user_cmdline(void)
}
}
- pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
- return SPECTRE_V2_USER_CMD_AUTO;
+ pr_err("Unknown user space protection option (%s). Switching to default\n", arg);
+ return mode;
}
static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode)
--
2.43.5
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