From 85b08180df07b9a5984b15ae31d76b904d42a115 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 13 Dec 2024 10:51:29 -0800 Subject: x86/cpu: Expose only stepping min/max interface The x86_match_cpu() infrastructure can match CPU steppings. Since there are only 16 possible steppings, the matching infrastructure goes all out and stores the stepping match as a bitmap. That means it can match any possible steppings in a single list entry. Fun. But it exposes this bitmap to each of the X86_MATCH_*() helpers when none of them really need a bitmap. It makes up for this by exporting a helper (X86_STEPPINGS()) which converts a contiguous stepping range into the bitmap which every single user leverages. Instead of a bitmap, have the main helper for this sort of thing (X86_MATCH_VFM_STEPS()) just take a stepping range. This ends up actually being even more compact than before. Leave the helper in place (renamed to __X86_STEPPINGS()) to make it more clear what is going on instead of just having a random GENMASK() in the middle of an already complicated macro. One oddity that I hit was this macro: X86_MATCH_VFM_STEPS(vfm, X86_STEPPING_MIN, max_stepping, issues) It *could* have been converted over to take a min/max stepping value for each entry. But that would have been a bit too verbose and would prevent the one oddball in the list (INTEL_COMETLAKE_L stepping 0) from sticking out. Instead, just have it take a *maximum* stepping and imply that the match is from 0=>max_stepping. This is functional for all the cases now and also retains the nice property of having INTEL_COMETLAKE_L stepping 0 stick out like a sore thumb. skx_cpuids[] is goofy. It uses the stepping match but encodes all possible steppings. Just use a normal, non-stepping match helper. Suggested-by: Ingo Molnar Signed-off-by: Dave Hansen Link: https://lore.kernel.org/all/20241213185129.65527B2A%40davehans-spike.ostc.intel.com --- include/linux/mod_devicetable.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/mod_devicetable.h') diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h index 4338b1b4ac44..d67614f7b7f1 100644 --- a/include/linux/mod_devicetable.h +++ b/include/linux/mod_devicetable.h @@ -700,6 +700,8 @@ struct x86_cpu_id { #define X86_FAMILY_ANY 0 #define X86_MODEL_ANY 0 #define X86_STEPPING_ANY 0 +#define X86_STEP_MIN 0 +#define X86_STEP_MAX 0xf #define X86_FEATURE_ANY 0 /* Same as FPU, you can't test for that */ /* -- cgit v1.2.3