x86/cpufeatures: Make CPU bugs sticky

CVE-2017-5754

There is currently no way to force CPU bug bits like CPU feature bits. That
makes it impossible to set a bug bit once at boot and have it stick for all
upcoming CPUs.

Extend the force set/clear arrays to handle bug bits as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.992156574@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 6cbd2171e89b13377261d15e64384df60ecb530e)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 225fd8374fae620cd221e7b4196f5c4baf35d70c..8b9915561ed17cf33982c9a4eeb114eaafa95041 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -134,6 +134,8 @@ extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit);
        set_bit(bit, (unsigned long *)cpu_caps_set);    \
 } while (0)
 
+#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)
+
 #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_X86_FAST_FEATURE_TESTS)
 /*
  * Static testing of CPU features.  Used the same as boot_cpu_has().

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index bccec7ed1676a15c6a8edd3e2b21d060c2bfe81e..59a317f8e0ec4d02cf49ac28c16297de955d2673 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -162,8 +162,8 @@ extern struct cpuinfo_x86   new_cpu_data;
 #include <linux/thread_info.h>
 
 extern struct x86_hw_tss       doublefault_tss;
-extern __u32                   cpu_caps_cleared[NCAPINTS];
-extern __u32                   cpu_caps_set[NCAPINTS];
+extern __u32                   cpu_caps_cleared[NCAPINTS + NBUGINTS];
+extern __u32                   cpu_caps_set[NCAPINTS + NBUGINTS];
 
 #ifdef CONFIG_SMP
 DECLARE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 7992e5a8076ccdb40c6009eed9ccd1c2e68cc807..fcdba90e08905994a03c835c8eb64f70c4c0542d 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -452,8 +452,8 @@ static const char *table_lookup_model(struct cpuinfo_x86 *c)
        return NULL;            /* Not found */
 }
 
-__u32 cpu_caps_cleared[NCAPINTS];
-__u32 cpu_caps_set[NCAPINTS];
+__u32 cpu_caps_cleared[NCAPINTS + NBUGINTS];
+__u32 cpu_caps_set[NCAPINTS + NBUGINTS];
 
 void load_percpu_segment(int cpu)
 {
@@ -812,7 +812,7 @@ static void apply_forced_caps(struct cpuinfo_x86 *c)
 {
        int i;
 
-       for (i = 0; i < NCAPINTS; i++) {
+       for (i = 0; i < NCAPINTS + NBUGINTS; i++) {
                c->x86_capability[i] &= ~cpu_caps_cleared[i];
                c->x86_capability[i] |= cpu_caps_set[i];
        }