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| author |   Josh Poimboeuf <jpoimboe@redhat.com> | 2019-04-02 10:00:51 -0500 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-14 19:19:41 +0200 |
| commit | f8a0bbe4bac879c0caf47ca699925ab29a4a9375 (patch) | |
| tree | a941dc5207181cb87719f1787f27f3a1098c520f | |
| parent | x86/speculation: Move arch_smt_update() call to after mitigation decisions (diff) | |
| download | linux-stable-f8a0bbe4bac879c0caf47ca699925ab29a4a9375.tar.xz linux-stable-f8a0bbe4bac879c0caf47ca699925ab29a4a9375.zip | |
x86/speculation/mds: Add SMT warning message
commit 39226ef02bfb43248b7db12a4fdccb39d95318e3 upstream.
MDS is vulnerable with SMT. Make that clear with a one-time printk
whenever SMT first gets enabled.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index a725105a49d1..6a3fcacbb9a0 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -667,6 +667,9 @@ static void update_indir_branch_cond(void) static_branch_disable(&switch_to_cond_stibp); } +#undef pr_fmt +#define pr_fmt(fmt) fmt + /* Update the static key controlling the MDS CPU buffer clear in idle */ static void update_mds_branch_idle(void) { @@ -687,6 +690,8 @@ static void update_mds_branch_idle(void) static_branch_disable(&mds_idle_clear); } +#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" + void arch_smt_update(void) { /* Enhanced IBRS implies STIBP. No update required. */ @@ -710,6 +715,8 @@ void arch_smt_update(void) switch (mds_mitigation) { case MDS_MITIGATION_FULL: case MDS_MITIGATION_VMWERV: + if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY)) + pr_warn_once(MDS_MSG_SMT); update_mds_branch_idle(); break; case MDS_MITIGATION_OFF: @@ -1139,6 +1146,7 @@ static int __init l1tf_cmdline(char *str) early_param("l1tf", l1tf_cmdline); #undef pr_fmt +#define pr_fmt(fmt) fmt #ifdef CONFIG_SYSFS |