diff options
| author | Borislav Petkov <bp@alien8.de> | 2010-10-04 09:31:27 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-10-04 11:22:24 -0700 |
| commit | 366d4a43b1a7a861c356a0e407c4f03f454d42ea (patch) | |
| tree | 29778279487b468584a1a2897c7f9c677c2bb172 /arch/x86/kernel/cpu/common.c | |
| parent | c2b9ff24a0df649d4d40947878b5b5ac39c7299e (diff) | |
x86, cpu: Fix X86_FEATURE_NOPL
ba0593bf553c450a03dbc5f8c1f0ff58b778a0c8 cleared the aforementioned
cpuid bit only on 32-bit due to various problems with Virtual PC. This
somehow got lost during the 32- + 64-bit merge so restore the feature
bit on 64-bit. For that, set it explicitly for non-constant arguments of
cpu_has(). Update comment for future reference.
Signed-off-by: Borislav Petkov <bp@alien8.de>
LKML-Reference: <20101004073127.GA20305@liondog.tnic>
Cc: Ryan O'Neill <ryan@innosecc.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f2f9ac7da25c..927e630aeaf3 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -704,16 +704,21 @@ void __init early_cpu_init(void) } /* - * The NOPL instruction is supposed to exist on all CPUs with - * family >= 6; unfortunately, that's not true in practice because - * of early VIA chips and (more importantly) broken virtualizers that - * are not easy to detect. In the latter case it doesn't even *fail* - * reliably, so probing for it doesn't even work. Disable it completely + * The NOPL instruction is supposed to exist on all CPUs of family >= 6; + * unfortunately, that's not true in practice because of early VIA + * chips and (more importantly) broken virtualizers that are not easy + * to detect. In the latter case it doesn't even *fail* reliably, so + * probing for it doesn't even work. Disable it completely on 32-bit * unless we can find a reliable way to detect all the broken cases. + * Enable it explicitly on 64-bit for non-constant inputs of cpu_has(). */ static void __cpuinit detect_nopl(struct cpuinfo_x86 *c) { +#ifdef CONFIG_X86_32 clear_cpu_cap(c, X86_FEATURE_NOPL); +#else + set_cpu_cap(c, X86_FEATURE_NOPL); +#endif } static void __cpuinit generic_identify(struct cpuinfo_x86 *c) |