On Wed, Jun 13, 2018 at 06:43:08PM +0000, Dave Hansen wrote: > > diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h > > index efc0d4bb3b35..d6edcabacfc7 100644 > > --- a/arch/x86/include/asm/mktme.h > > +++ b/arch/x86/include/asm/mktme.h > > @@ -43,6 +43,9 @@ void mktme_disable(void); > > void setup_direct_mapping_size(void); > > int sync_direct_mapping(void); > > > > +#define page_to_virt(x) \ > > + (__va(PFN_PHYS(page_to_pfn(x))) + page_keyid(x) * direct_mapping_size) > > This looks like a super important memory management function being > defined in some obscure Intel-specific feature header. How does that work?
No magic. It overwrites define in <linux/mm.h>. > > #else > > #define mktme_keyid_mask ((phys_addr_t)0) > > #define mktme_nr_keyids 0 > > diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h > > index 53c32af895ab..ffad496aadad 100644 > > --- a/arch/x86/include/asm/page_64.h > > +++ b/arch/x86/include/asm/page_64.h > > @@ -23,7 +23,7 @@ static inline unsigned long __phys_addr_nodebug(unsigned > > long x) > > /* use the carry flag to determine if x was < __START_KERNEL_map */ > > x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET)); > > > > - return x; > > + return x % direct_mapping_size; > > } > > What are the performance implications of this patch? Let me collect the numbers. -- Kirill A. Shutemov
