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authorThomas Gleixner <tglx@linutronix.de>2018-11-25 19:33:52 +0100
committerThomas Gleixner <tglx@linutronix.de>2018-11-28 11:57:13 +0100
commit6893a959d7fdebbab5f5aa112c277d5a44435ba1 (patch)
tree6f5ac01ddfe533889c8688185d9c3fdfff63f76e /arch
parent6d991ba509ebcfcc908e009d1db51972a4f7a064 (diff)
x86/speculation: Prepare arch_smt_update() for PRCTL mode
The upcoming fine grained per task STIBP control needs to be updated on CPU hotplug as well. Split out the code which controls the strict mode so the prctl control code can be added later. Mark the SMP function call argument __unused while at it. 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: Tim Chen <tim.c.chen@linux.intel.com> 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> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185005.759457117@linutronix.de
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/bugs.c46
1 files changed, 25 insertions, 21 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 29f40a92f5a8..9cab538e10f1 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -530,40 +530,44 @@ specv2_set_mode:
arch_smt_update();
}
-static bool stibp_needed(void)
+static void update_stibp_msr(void * __unused)
{
- /* Enhanced IBRS makes using STIBP unnecessary. */
- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
- return false;
-
- /* Check for strict user mitigation mode */
- return spectre_v2_user == SPECTRE_V2_USER_STRICT;
+ wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
}
-static void update_stibp_msr(void *info)
+/* Update x86_spec_ctrl_base in case SMT state changed. */
+static void update_stibp_strict(void)
{
- wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
+ u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
+
+ if (sched_smt_active())
+ mask |= SPEC_CTRL_STIBP;
+
+ if (mask == x86_spec_ctrl_base)
+ return;
+
+ pr_info("Update user space SMT mitigation: STIBP %s\n",
+ mask & SPEC_CTRL_STIBP ? "always-on" : "off");
+ x86_spec_ctrl_base = mask;
+ on_each_cpu(update_stibp_msr, NULL, 1);
}
void arch_smt_update(void)
{
- u64 mask;
-
- if (!stibp_needed())
+ /* Enhanced IBRS implies STIBP. No update required. */
+ if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
mutex_lock(&spec_ctrl_mutex);
- mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
- if (sched_smt_active())
- mask |= SPEC_CTRL_STIBP;
-
- if (mask != x86_spec_ctrl_base) {
- pr_info("Spectre v2 cross-process SMT mitigation: %s STIBP\n",
- mask & SPEC_CTRL_STIBP ? "Enabling" : "Disabling");
- x86_spec_ctrl_base = mask;
- on_each_cpu(update_stibp_msr, NULL, 1);
+ switch (spectre_v2_user) {
+ case SPECTRE_V2_USER_NONE:
+ break;
+ case SPECTRE_V2_USER_STRICT:
+ update_stibp_strict();
+ break;
}
+
mutex_unlock(&spec_ctrl_mutex);
}