On Thu, Dec 01, 2016 at 11:07:21AM +0100, Thomas Gleixner wrote:
> Yes, that makes a lot of sense.
Here it is:
---
From: Borislav Petkov
Date: Thu, 1 Dec 2016 12:11:37 +0100
Subject: [PATCH] x86/CPU: Add X86_FEATURE_CPUID
Add a synthetic CPUID flag denoting whether the CPU sports the CPUID
instruction or not. This will come useful later when accomodating
CPUID-less CPUs.
Signed-off-by: Borislav Petkov
---
arch/x86/include/asm/cpufeatures.h | 2 +-
arch/x86/kernel/cpu/common.c | 7 ---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h
b/arch/x86/include/asm/cpufeatures.h
index 53e27a12ceb6..cb49dd31c3b2 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -100,7 +100,7 @@
#define X86_FEATURE_XTOPOLOGY ( 3*32+22) /* cpu topology enum extensions */
#define X86_FEATURE_TSC_RELIABLE ( 3*32+23) /* TSC is known to be reliable */
#define X86_FEATURE_NONSTOP_TSC( 3*32+24) /* TSC does not stop in C
states */
-/* free, was #define X86_FEATURE_CLFLUSH_MONITOR ( 3*32+25) * "" clflush reqd
with monitor */
+#define X86_FEATURE_CPUID ( 3*32+25) /* CPU has CPUID instruction itself
*/
#define X86_FEATURE_EXTD_APICID( 3*32+26) /* has extended APICID (8
bits) */
#define X86_FEATURE_AMD_DCM ( 3*32+27) /* multi-node processor */
#define X86_FEATURE_APERFMPERF ( 3*32+28) /* APERFMPERF */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 90c007447507..8dcdcdeec569 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -800,14 +800,12 @@ static void __init early_identify_cpu(struct cpuinfo_x86
*c)
memset(&c->x86_capability, 0, sizeof c->x86_capability);
c->extended_cpuid_level = 0;
- if (!have_cpuid_p())
- identify_cpu_without_cpuid(c);
-
/* cyrix could have cpuid enabled via c_identify()*/
if (have_cpuid_p()) {
cpu_detect(c);
get_cpu_vendor(c);
get_cpu_cap(c);
+ setup_force_cpu_cap(X86_FEATURE_CPUID);
if (this_cpu->c_early_init)
this_cpu->c_early_init(c);
@@ -817,6 +815,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
if (this_cpu->c_bsp_init)
this_cpu->c_bsp_init(c);
+} else {
+ identify_cpu_without_cpuid(c);
+ setup_clear_cpu_cap(X86_FEATURE_CPUID);
}
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
--
2.10.0
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
