[PATCH 0/2] x86/tsc: Update tsc crystal_khz whitelist

[PATCH 0/2] x86/tsc: Update tsc crystal_khz whitelist

[Prarit Bhargava]

native_calibrate_tsc() contains a whitelist of models that have a known
TSC frequency that differs from the CPU frequency.  This patchset
switches the code from using magic numbers to using the defines in
asm/intel-family.h and adds new processors to the whitelist.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Rafael Aquini <aquini@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: lenb@kernel.org

Prarit Bhargava (2):
  x86,tsc: Use cpu id defines from intel-family.h
  x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

 arch/x86/kernel/tsc.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

-- 
1.7.9.3

[PATCH 1/2] x86,tsc: Use cpu id defines from intel-family.h

[Prarit Bhargava]

asm/intel-family.h contains defines for cpu ids which should be
used in the native_calibrate_tsc() function.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Rafael Aquini <aquini@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: lenb@kernel.org
---
 arch/x86/kernel/tsc.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 78b9cb5a26af..2344758ba8a3 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -23,6 +23,7 @@
 #include <asm/x86_init.h>
 #include <asm/geode.h>
 #include <asm/apic.h>
+#include <asm/intel-family.h>
 
 unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
@@ -686,11 +687,11 @@ unsigned long native_calibrate_tsc(void)
 
 	if (crystal_khz == 0) {
 		switch (boot_cpu_data.x86_model) {
-		case 0x4E:	/* SKL */
-		case 0x5E:	/* SKL */
+		case INTEL_FAM6_SKYLAKE_MOBILE:
+		case INTEL_FAM6_SKYLAKE_DESKTOP:
 			crystal_khz = 24000;	/* 24.0 MHz */
 			break;
-		case 0x5C:	/* BXT */
+		case INTEL_FAM6_ATOM_GOLDMONT:
 			crystal_khz = 19200;	/* 19.2 MHz */
 			break;
 		}
-- 
1.7.9.3

[PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

[Prarit Bhargava]

In commit aa297292d708 ("x86/tsc: Enumerate SKL cpu_khz and tsc_khz via
CPUID"), the kernel added support for Intel processors which had
a different CPU base-frequency and TSC frequency.

The turbostat utility has been updated with KBL and SKX processors,
and they should also be added to the crystal_khz white list.

For example, on INTEL_FAM6_KABYLAKE_MOBILE native_calibrate_tsc() returns 0 MHz
for tsc_khz and after this patch native_calibrate_tsc() returns 1608 MHz.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Rafael Aquini <aquini@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: lenb@kernel.org
---
 arch/x86/kernel/tsc.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 2344758ba8a3..dfa70a8867dc 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -689,11 +689,18 @@ unsigned long native_calibrate_tsc(void)
 		switch (boot_cpu_data.x86_model) {
 		case INTEL_FAM6_SKYLAKE_MOBILE:
 		case INTEL_FAM6_SKYLAKE_DESKTOP:
+		case INTEL_FAM6_KABYLAKE_MOBILE:
+		case INTEL_FAM6_KABYLAKE_DESKTOP:
 			crystal_khz = 24000;	/* 24.0 MHz */
 			break;
+		case INTEL_FAM6_SKYLAKE_X:
+			crystal_khz = 24000;	/* 25.0 MHz */
+			break;
 		case INTEL_FAM6_ATOM_GOLDMONT:
 			crystal_khz = 19200;	/* 19.2 MHz */
 			break;
+		default:
+			crystal_khz = 0;
 		}
 	}
 
-- 
1.7.9.3

Re: [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

[Peter Zijlstra]

On Thu, Sep 15, 2016 at 11:04:18AM -0400, Prarit Bhargava wrote:
> +++ b/arch/x86/kernel/tsc.c
> @@ -689,11 +689,18 @@ unsigned long native_calibrate_tsc(void)
>  		switch (boot_cpu_data.x86_model) {
>  		case INTEL_FAM6_SKYLAKE_MOBILE:
>  		case INTEL_FAM6_SKYLAKE_DESKTOP:
> +		case INTEL_FAM6_KABYLAKE_MOBILE:
> +		case INTEL_FAM6_KABYLAKE_DESKTOP:
>  			crystal_khz = 24000;	/* 24.0 MHz */
>  			break;
> +		case INTEL_FAM6_SKYLAKE_X:
> +			crystal_khz = 24000;	/* 25.0 MHz */

					^^^  !=   ^^^^

did you mean to type: 25000 ?

> +			break;
>  		case INTEL_FAM6_ATOM_GOLDMONT:
>  			crystal_khz = 19200;	/* 19.2 MHz */
>  			break;
> +		default:
> +			crystal_khz = 0;
>  		}
>  	}
>  
> -- 
> 1.7.9.3
> 

RE: [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

[Brown, Len]

> +			crystal_khz = 24000;	/* 25.0 MHz */

I guess I prefer no comment over an incorrect comment.

Re: [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

[Peter Zijlstra]

On Thu, Sep 15, 2016 at 04:08:36PM +0000, Brown, Len wrote:
> > +			crystal_khz = 24000;	/* 25.0 MHz */
> 
> I guess I prefer no comment over an incorrect comment.
> 

>From this I take it it should really have been 24 MHz and it could have
joined the existing case. I assumed (ha!) that since it had a special
separate case the comment was correct.

Re: [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

[Prarit Bhargava]

On 09/15/2016 01:43 PM, Peter Zijlstra wrote:
> On Thu, Sep 15, 2016 at 04:08:36PM +0000, Brown, Len wrote:
>>> +			crystal_khz = 24000;	/* 25.0 MHz */
>>
>> I guess I prefer no comment over an incorrect comment.
>>
> 
> From this I take it it should really have been 24 MHz and it could have
> joined the existing case. I assumed (ha!) that since it had a special
> separate case the comment was correct.

AFAICT, it should be 25000.  Len -- can you explicitly confirm that?  The
turbostat code contains (tools/power/x86/turbostat/turbostat.c:3312)

                                case 0x55:      /* SKX */
                                        crystal_hz = 25000000;  /* 25.0 MHz */


P.

>