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Intel sometimes has CPUs with identical family/model/stepping but
which need different microcode. These CPUs are differentiated with the
platform ID.
The Intel "microcode-20250512" release was used to generate the
existing contents of intel-ucode-defs.h. Use that same release and add
the platform mask to the definitions.
This makes the list a few entries longer because some CPUs previously
that shared a definition now need two or more. for example for the
ancient Pentium III there are two CPUs that differ only in their
platform and have two different microcode versions (note:
.driver_data is the microcode version):
{ ..., .model = 0x05, .steppings = 0x0001, .platform_mask = 0x01, .driver_data = 0x40 },
{ ..., .model = 0x05, .steppings = 0x0001, .platform_mask = 0x08, .driver_data = 0x45 },
Another example is the state-of-the-art Granite Rapids:
{ ..., .model = 0xad, .steppings = 0x0002, .platform_mask = 0x20, .driver_data = 0xa0000d1 },
{ ..., .model = 0xad, .steppings = 0x0002, .platform_mask = 0x95, .driver_data = 0x10003a2 },
As you can see, this differentiation with platform ID has been
necessary for a long time and is still relevant today.
Without the platform matching, the old microcode table is incomplete.
For instance, it might lead someone with a Pentium III, platform 0x0,
and microcode 0x40 to think that they should have microcode 0x45,
which is really only for platform 0x4 (.platform_mask==0x08).
In practice, this meant that folks with fully updated microcode were
seeing "Vulnerable" in the "old_microcode" file.
1. https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files
Closes: https://lore.kernel.org/all/38660F8F-499E-48CD-B58B-4822228A5941@nutanix.com/
Fixes:
|
||
|---|---|---|
| .. | ||
| amd_shas.c | ||
| amd.c | ||
| core.c | ||
| intel-ucode-defs.h | ||
| intel.c | ||
| internal.h | ||
| Makefile | ||