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Subject[PATCH 4.9 68/96] x86/cpufeatures: Make CPU bugs sticky
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@linutronix.de>

commit 6cbd2171e89b13377261d15e64384df60ecb530e upstream.

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>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/cpufeature.h | 2 ++
arch/x86/include/asm/processor.h | 4 ++--
arch/x86/kernel/cpu/common.c | 6 +++---
3 files changed, 7 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -135,6 +135,8 @@ extern const char * const x86_bug_flags[
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().
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -156,8 +156,8 @@ extern struct cpuinfo_x86 boot_cpu_data;
extern struct cpuinfo_x86 new_cpu_data;

extern struct tss_struct 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);
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -480,8 +480,8 @@ static const char *table_lookup_model(st
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)
{
@@ -710,7 +710,7 @@ static void apply_forced_caps(struct cpu
{
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];
}

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