Re: [PATCH 3/6] x86: Define some Intel vPMU leafs

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

Le 24/03/2026 à 10:25, Jan Beulich a écrit :
> On 10.03.2026 17:44, Teddy Astie wrote:
>> --- a/xen/include/xen/lib/x86/cpu-policy.h
>> +++ b/xen/include/xen/lib/x86/cpu-policy.h
>> @@ -162,7 +162,15 @@ struct cpu_policy
>>               uint64_t :64, :64; /* Leaf 0x9 - DCA */
>>
>>               /* Leaf 0xa - Intel PMU. */
>> -            uint8_t pmu_version, _pmu[15];
>> +            struct {
>> +                uint8_t /* a */ version, num_gp_ctrs, gp_ctr_width,
>> +                                event_enum_length;
>> +                uint32_t /* b */:32;
>> +                uint32_t /* c */ fixed_ctr_mask;
>> +                uint32_t /* d */ num_fixed_ctr:5, fixed_ctr_width:8, :1,
>> +                                 anythread_depreciation:1, slots_per_cyc:4,
>> +                                 :13;
>> +            } pmu;
>
> Style-wise this looks to follow e.g. the cache leaf, so perhaps okay, even
> if I would have preferred you to follow what we did for leaf 6.

My idea was to put all that as .pmu.*, so I wouldn't need to prefix
everything with "pmu_". I'm not sure if you're talking about a different
approach.

 > The named> boolean field, however, wants to be of type bool.

Which fields ?

 > And then the unnamed 1-bit> field really wants to be 2 bits, for
anythread_depreciation to be bit 15
> (etc).
>

Ah yes thanks, I got confused with the fields size for a second.
I also found that slots_per_cyc is 3 bits instead of 4.

I think this diff fixes it overall.

diff --git a/xen/include/xen/lib/x86/cpu-policy.h
b/xen/include/xen/lib/x86/cpu-policy.h
index 9161e2ad8d..796c2edb0e 100644
--- a/xen/include/xen/lib/x86/cpu-policy.h
+++ b/xen/include/xen/lib/x86/cpu-policy.h
@@ -167,9 +167,9 @@ struct cpu_policy
                                  event_enum_length;
                  uint32_t /* b */:32;
                  uint32_t /* c */ fixed_ctr_mask;
-                uint32_t /* d */ num_fixed_ctr:5, fixed_ctr_width:8, :1,
-                                 anythread_depreciation:1, slots_per_cyc:4,
-                                 :13;
+                uint32_t /* d */ num_fixed_ctr:5, fixed_ctr_width:8, :2,
+                                 anythread_depreciation:1, slots_per_cyc:3,
+                                 :11;
              } pmu;

              uint64_t :64, :64; /* Leaf 0xb - Topology. */

Making the first edx reserved gap actually 2 bits, slots_per_cyc
actually 3 bits and adjusting the end reserved part that is actually 11
bits.

> Jan
>

Teddy


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Teddy Astie | Vates XCP-ng Developer

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