lkml.org 
[lkml]   [2018]   [Jun]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCHv4 17/18] x86/mm: Handle encrypted memory in page_to_virt() and __pa()
From
Date
> diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
> index ba83fba4f9b3..dbfbd955da98 100644
> --- a/arch/x86/include/asm/mktme.h
> +++ b/arch/x86/include/asm/mktme.h
> @@ -29,6 +29,9 @@ void arch_free_page(struct page *page, int order);
>
> int sync_direct_mapping(void);
>
> +#define page_to_virt(x) \
> + (__va(PFN_PHYS(page_to_pfn(x))) + page_keyid(x) * direct_mapping_size)

Please put this in a generic header so that this hunk represents the
*default* x86 implementation that is used universally on x86. Then,
please do

#ifndef CONFIG_MKTME_WHATEVER
#define page_keyid(x) (0)
#endif

> #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;

There are almost *surely* performance implications from this that affect
anyone with this compile option turned on. There's now a 64-bit integer
division operation which is used in places like kfree().

That's a show-stopper for me until we've done some pretty comprehensive
performance analysis of this, which means much more than one kernel
compile test on one system.

\
 
 \ /
  Last update: 2018-06-26 19:28    [W:0.335 / U:0.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site