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>>> This is the existing code, however it would be better to use wrmsrl() >>> when the higher 32-bit are all 0s: >>> >>>      wrmsrl(MSR_IA32_EVT_CFG_BASE + index, mon_info->mon_config); >>> >> Could you please elaborate what makes this change better? > > In short, it takes one less argument, and doesn't pass an argument of 0. > > The longer story is that hpa and I are refactoring the MSR access APIs > to accommodate the immediate form of MSR access instructions.  And we > are not happy about that there are too many MSR access APIs and their > uses are *random*.  The native wrmsr() and wrmsrl() are essentially the > same and the only difference is that wrmsr() passes a 64-bit value to be > written into a MSR in *2* u32 arguments.  But we already have struct msr > defined in asm/shared/msr.h as: >     struct msr { >             union { >                     struct { >                             u32 l; >                             u32 h; >                     }; >                     u64 q; >             }; >     }; > > it's more natural to do the same job with this data structure in most > cases.  And we want to remove wrmsr() and only keep wrmsrl(), thus a > developer won't have to figure out which one is better to use :-P. > > For that to happen, one cleanup is to replace wrmsr(msr, low, 0) with > wrmsrl(msr, low) (low is automatically converted to u64 from u32). > > However, I'm fine if Babu wants to keep it as-is. Thanks for the explanation. Changed it to use wrmsrl(). -- Thanks Babu Moger