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| author | Dave Hansen <dave.hansen@linux.intel.com> | 2026-03-04 21:10:22 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2026-03-05 23:25:38 +0300 |
| commit | fab0c75d500fd23de6ea1b30e44635418a6dae65 (patch) | |
| tree | 8aac2620ac8d58a6e19ef1ccd440e0b2603a90f7 /include/linux | |
| parent | d8630b67ca1edeea728dbb309b09d239e9db6bdf (diff) | |
| download | linux-fab0c75d500fd23de6ea1b30e44635418a6dae65.tar.xz | |
x86/cpu: Add platform ID to CPU matching structure
The existing x86_match_cpu() infrastructure can be used to match
a bunch of attributes of a CPU: vendor, family, model, steppings
and CPU features.
But, there's one more attribute that's missing and unable to be
matched against: the platform ID, enumerated on Intel CPUs in
MSR_IA32_PLATFORM_ID. It is a little more obscure and is only
queried during microcode loading. This is because Intel sometimes
has CPUs with identical family/model/stepping but which need
different microcode. These CPUs are differentiated with the
platform ID.
Add a field in 'struct x86_cpu_id' for the platform ID. Similar
to the stepping field, make the new field a mask of platform IDs.
Some examples:
0x01: matches only platform ID 0x0
0x02: matches only platform ID 0x1
0x03: matches platform IDs 0x0 or 0x1
0x80: matches only platform ID 0x7
0xff: matches all 8 possible platform IDs
Since the mask is only a byte wide, it nestles in next to another
u8 and does not even increase the size of 'struct x86_cpu_id'.
Reserve the all 0's value as the wildcard (X86_PLATFORM_ANY). This
avoids forcing changes to existing 'struct x86_cpu_id' users. They
can just continue to fill the field with 0's and their matching will
work exactly as before.
Note: If someone is ever looking for space in 'struct x86_cpu_id',
this new field could probably get stuck over in ->driver_data
for the one user that there is.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://patch.msgid.link/20260304181022.058DF07C@davehans-spike.ostc.intel.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mod_devicetable.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h index 5b1725fe9707..23ff24080dfd 100644 --- a/include/linux/mod_devicetable.h +++ b/include/linux/mod_devicetable.h @@ -691,6 +691,7 @@ struct x86_cpu_id { __u16 feature; /* bit index */ /* Solely for kernel-internal use: DO NOT EXPORT to userspace! */ __u16 flags; + __u8 platform_mask; __u8 type; kernel_ulong_t driver_data; }; @@ -702,6 +703,7 @@ struct x86_cpu_id { #define X86_STEPPING_ANY 0 #define X86_STEP_MIN 0 #define X86_STEP_MAX 0xf +#define X86_PLATFORM_ANY 0x0 #define X86_FEATURE_ANY 0 /* Same as FPU, you can't test for that */ #define X86_CPU_TYPE_ANY 0 |