[3/3] x86/Intel: also display CPU freq for family 0xf

Commit Message

Jan Beulich Feb. 10, 2022, 2:56 p.m. UTC

Actually we can do better than simply bailing for there not being any
PLATFORM_INFO MSR on these. The "max" part of the information is
available in another MSR, alongside the scaling factor (which is
encoded in similar ways to Core/Core2, and hence the decoding table can
be shared).

Signed-off-by: Jan Beulich <[e-mail]>
---
The inner switch() is left indented one level too much (and with an
extra pair of braces) to limit the diff. I'd prefer to make a follow-up
patch reducing the indentation, unless I'm told to do so right here.

Comments

Roger Pau Monné Feb. 11, 2022, 10:22 a.m. UTC | #1

On Thu, Feb 10, 2022 at 03:56:48PM +0100, Jan Beulich wrote:
> Actually we can do better than simply bailing for there not being any
> PLATFORM_INFO MSR on these. The "max" part of the information is
> available in another MSR, alongside the scaling factor (which is
> encoded in similar ways to Core/Core2, and hence the decoding table can
> be shared).
> 
> Signed-off-by: Jan Beulich <[e-mail]>

Acked-by: Roger Pau Monné <[e-mail]>

> ---
> The inner switch() is left indented one level too much (and with an
> extra pair of braces) to limit the diff. I'd prefer to make a follow-up
> patch reducing the indentation, unless I'm told to do so right here.

I'm fine with a followup patch.

> --- a/xen/arch/x86/cpu/intel.c
> +++ b/xen/arch/x86/cpu/intel.c
> @@ -412,9 +412,9 @@ static int num_cpu_cores(struct cpuinfo_
>  
>  static void intel_log_freq(const struct cpuinfo_x86 *c)
>  {
> -    unsigned int eax, ebx, ecx, edx;
> +    unsigned int eax, ebx, ecx, edx, factor;
>      uint64_t msrval;
> -    uint8_t max_ratio;
> +    uint8_t max_ratio, min_ratio;
>  
>      if ( c->cpuid_level >= 0x15 )
>      {
> @@ -455,21 +455,22 @@ static void intel_log_freq(const struct
>          }
>      }
>  
> -    if ( c->x86 == 0xf || rdmsr_safe(MSR_INTEL_PLATFORM_INFO, msrval) )
> -        return;
> -    max_ratio = msrval >> 8;
> -
> -    if ( max_ratio )
> +    switch ( c->x86 )
>      {
> -        unsigned int factor = 10000;
> -        uint8_t min_ratio = msrval >> 40;
> +        static const unsigned short core_factors[] =

This no longer applies to Core models only, so I wouldn't be opposed
to renaming to scaling_factors or similar.

Thanks, Roger.

Patch

--- a/xen/arch/x86/cpu/intel.c
+++ b/xen/arch/x86/cpu/intel.c
@@ -412,9 +412,9 @@  static int num_cpu_cores(struct cpuinfo_
 
 static void intel_log_freq(const struct cpuinfo_x86 *c)
 {
-    unsigned int eax, ebx, ecx, edx;
+    unsigned int eax, ebx, ecx, edx, factor;
     uint64_t msrval;
-    uint8_t max_ratio;
+    uint8_t max_ratio, min_ratio;
 
     if ( c->cpuid_level >= 0x15 )
     {
@@ -455,21 +455,22 @@  static void intel_log_freq(const struct
         }
     }
 
-    if ( c->x86 == 0xf || rdmsr_safe(MSR_INTEL_PLATFORM_INFO, msrval) )
-        return;
-    max_ratio = msrval >> 8;
-
-    if ( max_ratio )
+    switch ( c->x86 )
     {
-        unsigned int factor = 10000;
-        uint8_t min_ratio = msrval >> 40;
+        static const unsigned short core_factors[] =
+            { 26667, 13333, 20000, 16667, 33333, 10000, 40000 };
+
+    case 6:
+        if ( rdmsr_safe(MSR_INTEL_PLATFORM_INFO, msrval) )
+            return;
+        max_ratio = msrval >> 8;
+        min_ratio = msrval >> 40;
+        if ( !max_ratio )
+            return;
 
-        if ( c->x86 == 6 )
+        {
             switch ( c->x86_model )
             {
-                static const unsigned short core_factors[] =
-                    { 26667, 13333, 20000, 16667, 33333, 10000, 40000 };
-
             case 0x0e: /* Core */
             case 0x0f: case 0x16: case 0x17: case 0x1d: /* Core2 */
                 /*
@@ -491,13 +492,33 @@  static void intel_log_freq(const struct
             case 0x25: case 0x2c: case 0x2f: /* Westmere */
                 factor = 13333;
                 break;
+
+            default:
+                factor = 10000;
+                break;
             }
+        }
+        break;
+
+    case 0xf:
+        if ( rdmsr_safe(MSR_IA32_EBC_FREQUENCY_ID, msrval) )
+            return;
+        max_ratio = msrval >> 24;
+        min_ratio = 0;
+        msrval >>= 16;
+        if ( (msrval &= 7) > 4 )
+            return;
+        factor = core_factors[msrval];
+        break;
 
-        printk("CPU%u: ", smp_processor_id());
-        if ( min_ratio )
-            printk("%u ... ", (factor * min_ratio + 50) / 100);
-        printk("%u MHz\n", (factor * max_ratio + 50) / 100);
+    default:
+        return;
     }
+
+    printk("CPU%u: ", smp_processor_id());
+    if ( min_ratio )
+        printk("%u ... ", (factor * min_ratio + 50) / 100);
+    printk("%u MHz\n", (factor * max_ratio + 50) / 100);
 }
 
 static void init_intel(struct cpuinfo_x86 *c)