Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

Christoph Hellwig
2017-09-08T07:51:42Z

I think this patch needs to be split into the generic mm code, and
the x86 arch code at least.

> +/*
> + * The current flushing context - we pass it instead of 5 arguments:
> + */
> +struct cpa_data {
> + unsigned long *vaddr;
> + pgd_t *pgd;
> + pgprot_t mask_set;
> + pgprot_t mask_clr;
> + unsigned long numpages;
> + int flags;
> + unsigned long pfn;
> + unsigned force_split : 1;
> + int curpage;
> + struct page **pages;
> +};

Fitting these 10 variables into 5 arguments would require an awesome
compression scheme anyway :)

> + if (__split_large_page(&cpa, pte, (unsigned long)kaddr, base) < 0)

Overly long line.

> +#include <linux/xpfo.h>
>
> #include <asm/cacheflush.h>
>
> @@ -55,24 +56,34 @@ static inline struct page *kmap_to_page(void *addr)
> #ifndef ARCH_HAS_KMAP
> static inline void *kmap(struct page *page)
> {
> + void *kaddr;
> +
> might_sleep();
> - return page_address(page);
> + kaddr = page_address(page);
> + xpfo_kmap(kaddr, page);
> + return kaddr;
> }
>
> static inline void kunmap(struct page *page)
> {
> + xpfo_kunmap(page_address(page), page);
> }
>
> static inline void *kmap_atomic(struct page *page)
> {
> + void *kaddr;
> +
> preempt_disable();
> pagefault_disable();
> - return page_address(page);
> + kaddr = page_address(page);
> + xpfo_kmap(kaddr, page);
> + return kaddr;
> }

It seems to me like we should simply direct to pure xpfo
implementations for the !HIGHMEM && XPFO case. - that is
just have the prototypes for kmap, kunmap and co in
linux/highmem.h and implement them in xpfo under those names.

Instead of sprinkling them around.

> +DEFINE_STATIC_KEY_FALSE(xpfo_inited);

s/inited/initialized/g ?

> + bool "Enable eXclusive Page Frame Ownership (XPFO)"
> + default n

default n is the default, so you can remove this line.