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| author | Tim Chen <tim.c.chen@linux.intel.com> | 2018-11-25 21:33:33 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-14 20:19:35 +0300 |
| commit | 8a7723de5e1a57c394d885e731af6ebba990f110 (patch) | |
| tree | 52b43b4b760daea9fec603cb7da6626b5797ed42 | |
| parent | 20ba13aef2628548b515b4dc31ca5a5f2baa9bbd (diff) | |
| download | linux-8a7723de5e1a57c394d885e731af6ebba990f110.tar.xz | |
x86/speculation: Disable STIBP when enhanced IBRS is in use
commit 34bce7c9690b1d897686aac89604ba7adc365556 upstream.
If enhanced IBRS is active, STIBP is redundant for mitigating Spectre v2
user space exploits from hyperthread sibling.
Disable STIBP when enhanced IBRS is used.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20181125185003.966801480@linutronix.de
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 | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 64e5f64c3b38..364fd880feef 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -325,6 +325,10 @@ static bool stibp_needed(void) if (spectre_v2_enabled == SPECTRE_V2_NONE) return false; + /* Enhanced IBRS makes using STIBP unnecessary. */ + if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + return false; + if (!boot_cpu_has(X86_FEATURE_STIBP)) return false; @@ -852,6 +856,9 @@ static ssize_t l1tf_show_state(char *buf) static char *stibp_state(void) { + if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + return ""; + if (x86_spec_ctrl_base & SPEC_CTRL_STIBP) return ", STIBP"; else |