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Date: Mon, 15 Apr 2019 08:58:52 -0700 From: Dave Hansen <dave.hansen@...el.com> To: "Singh, Brijesh" <brijesh.singh@....com>, "x86@...nel.org" <x86@...nel.org> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Dan Williams <dan.j.williams@...el.com>, "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>, "H . Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, "Lendacky, Thomas" <Thomas.Lendacky@....com> Subject: Re: [PATCH v2] x86: mm: Do not use set_{pud,pmd}_safe when splitting the large page On 4/15/19 7:55 AM, Singh, Brijesh wrote: > static unsigned long __meminit > phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end, > - pgprot_t prot) > + pgprot_t prot, bool safe) > { > unsigned long pages = 0, paddr_next; > unsigned long paddr_last = paddr_end; > @@ -432,7 +463,7 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end, > E820_TYPE_RAM) && > !e820__mapped_any(paddr & PAGE_MASK, paddr_next, > E820_TYPE_RESERVED_KERN)) > - set_pte_safe(pte, __pte(0)); > + __set_pte(pte, __pte(0), safe); > continue; > } The changelog is great, btw. But, I'm not a big fan of propagating the 'safe' nomenclature. Could we, at least, call it 'overwrite_safe' or something if we're going to have a variable name? Or even, 'new_entries_only' or something that actually conveys meaning? Because, just reading it, I always wonder "why do we have an unsafe variant, that's stupid" every time. :) > +#define DEFINE_ENTRY(type1, type2, safe) \ > +static inline void __set_##type1(type1##_t *arg1, \ > + type2##_t arg2, bool safe) \ > +{ \ > + if (safe) \ > + set_##type1##_safe(arg1, arg2); \ > + else \ > + set_##type1(arg1, arg2); \ > +} While I appreciate the brevity that these macros allow, I detest their ability to thwart cscope and grep. I guess it's just one file, but it does make me grumble a bit. Also, can we do better than "__"? Aren't these specific to initialization, and only for the kernel? Maybe we should call them meminit_set_pte() or kern_set_pte() or something so make it totally clear to the reader that they're new. > - kernel_physical_mapping_init(__pa(vaddr & pmask), > - __pa((vaddr_end & pmask) + psize), > - split_page_size_mask); > + kernel_physical_mapping_change(__pa(vaddr & pmask), > + __pa((vaddr_end & pmask) + psize), > + split_page_size_mask); BTW, this hunk is really nice the way that the new naming makes it more intuitive what's going on. My only nit w9uld be that we now have two very similarly-named functions with different TLB-flushing requirements. Could we please include a comment at this site that reminds us that we owe a TLB flush after this?
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