Messages in this thread | | | Date | Mon, 15 Aug 2022 09:43:00 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/5] x86/microcode/intel: Allow a late-load only if a min rev is specified |
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On Sat, Aug 13, 2022 at 10:38:23PM +0000, Ashok Raj wrote:
> The proposal here is an even simpler option. The criteria for a microcode to > be a viable late-load candidate is that no CPUID or OS visible MSR features > are removed with respect to an earlier version of the microcode. > > Pseudocode for late-load is as follows: > > if header.min_required_id == 0 > This is old format microcode, block late-load > else if current_ucode_version < header.min_required_id > Current version is too old, block late-load of this microcode. > else > OK to proceed with late-load.
What about ucode that adds CPUID bits? Since the kernel will not re-init it will not pick up on those. But userspace might.
Should we at all time enable CPUID intercept to ensure user visible CPUID doesn't change?
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