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Specifically: >>> >>> resctrl_cpu_detect(): >>>     if (!cpu_has(c, X86_FEATURE_CQM_LLC)) { >>>         c->x86_cache_max_rmid  = -1; >>>         ... >>>     } >>> >>> The function modified by this patch, rdt_get_mon_l3_config() only runs if >>> the hardware supports one or more of the L3 monitoring sub-features >>> (X86_FEATURE_CQM_OCCUP_LLC, X86_FEATURE_CQM_MBM_TOTAL, or >>> X86_FEATURE_CQM_MBM_LOCAL) that depend on X86_FEATURE_CQM_LLC per cpuid_deps[]. >>> >>> I tried to reproduce the issue on real hardware by using clearcpuid to >>> disable X86_FEATURE_CQM_LLC and the CPUID dependencies did the right thing >>> by automatically disabling X86_FEATURE_CQM_OCCUP_LLC, X86_FEATURE_CQM_MBM_TOTAL, >>> X86_FEATURE_CQM_MBM_LOCAL, not running rdt_get_mon_l3_config() at all, and >>> not even attempt to enumerate any of the L3 monitoring details. >>> >>> What are the symptoms when you encounter this issue? >> >> Linux crashes during boot with a divide error, and the splat backtrace is in rdt_get_mon_l3_config(). >> >>> Would it be possible to send me the CPUID flags of leaf 7, subleaf 0 as >>> well as all sub-leaves of leaf 0xF? >> >> # ./cpuid 0x7 0 >> CPUID for Leaf 0x00000007, Sublevel 0x00000000: >>     eax: 00000002 >>     ebx: f1bf2ffb > > Looks like X86_FEATURE_CQM_LLC is off. > >>     ecx: 1b415f7e >>     edx: bc814410 >> >> # ./cpuid 0x7 1 >> CPUID for Leaf 0x00000007, Sublevel 0x00000001: >>     eax: 00201c30 >>     ebx: 00000000 >>     ecx: 00000000 >>     edx: 00084000 >> >> # ./cpuid 0x7 2 >> CPUID for Leaf 0x00000007, Sublevel 0x00000002: >>     eax: 00000000 >>     ebx: 00000000 >>     ecx: 00000000 >>     edx: 0000003f >> > > Thank you. Could you please also pass on all sub-leaves of leaf 0xF? > One more thing, could you please check the kernel logs for any other issues when that VM boots up? I would like to check if it contains a warning with text like: "x86 CPU feature dependency check failure" Reinette