On 18/07/2025 11:23 am, Andrew Cooper wrote: > On 18/07/2025 11:19 am, Jan Beulich wrote: >> On 18.07.2025 12:07, Andrew Cooper wrote: >>> With the ability to match on steppings, introduce a new X86_MATCH_VFMS() >>> helper to match a specific stepping, and use it to rework deadline_match[]. >>> >>> Notably this removes the overloading of driver_data possibly being a >>> function >>> pointer, and removes the latent bug where the target functions are missing >>> ENDBR instructions owing to the lack of the cf_check attribute. >>> >>> No functional change. >>> >>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> >> Reviewed-by: Jan Beulich <jbeul...@suse.com> > Thanks.
Actually, this isn't as no-functional-change as I thought. X86_FEATURE_TSC_DEADLINE has been swapped for X86_FEATURE_ANY in the table. check_deadline_errata() is called unconditionally, without checking for TSC_DEADLINE, yet the rows in the table are the CPUs for which an erratum is known, so they all have the feature. It does make a difference if e.g. one were to boot with cpuid=no-tsc-deadline. Previously we'd have exited early, while now we'll emit the warning. We could switch back to using TSC_DEADLINE (requiring a more complicated X86_MATCH_*() wrapper), although a better option would be to predicate the call to check_deadline_errata() with a feature check, because it's a much more recent addition to AMD CPUs, and there's no point searching the errata list on CPUs which lack the feature. Thoughts? ~Andrew
