diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-08-12 08:40:19 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-08-12 08:40:19 -0700 |
commit | 1c89ac55017f982355c7761e1c912c88c941483d (patch) | |
tree | 6878e95a0572defc725ea58f5a1449db937a5066 /drivers/lguest/page_tables.c | |
parent | 88fa08f67bee1a0c765237bdac106a32872f57d2 (diff) | |
parent | b1b135c8d619cb2c7045d6ee4e48375882518bb5 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
fix spinlock recursion in hvc_console
stop_machine: remove unused variable
modules: extend initcall_debug functionality to the module loader
export virtio_rng.h
lguest: use get_user_pages_fast() instead of get_user_pages()
mm: Make generic weak get_user_pages_fast and EXPORT_GPL it
lguest: don't set MAC address for guest unless specified
Diffstat (limited to 'drivers/lguest/page_tables.c')
-rw-r--r-- | drivers/lguest/page_tables.c | 25 |
1 files changed, 9 insertions, 16 deletions
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index d93500f24fb..81d0c605344 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -108,9 +108,8 @@ static unsigned long gpte_addr(pgd_t gpgd, unsigned long vaddr) } /*:*/ -/*M:014 get_pfn is slow; it takes the mmap sem and calls get_user_pages. We - * could probably try to grab batches of pages here as an optimization - * (ie. pre-faulting). :*/ +/*M:014 get_pfn is slow: we could probably try to grab batches of pages here as + * an optimization (ie. pre-faulting). :*/ /*H:350 This routine takes a page number given by the Guest and converts it to * an actual, physical page number. It can fail for several reasons: the @@ -123,19 +122,13 @@ static unsigned long gpte_addr(pgd_t gpgd, unsigned long vaddr) static unsigned long get_pfn(unsigned long virtpfn, int write) { struct page *page; - /* This value indicates failure. */ - unsigned long ret = -1UL; - /* get_user_pages() is a complex interface: it gets the "struct - * vm_area_struct" and "struct page" assocated with a range of pages. - * It also needs the task's mmap_sem held, and is not very quick. - * It returns the number of pages it got. */ - down_read(¤t->mm->mmap_sem); - if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT, - 1, write, 1, &page, NULL) == 1) - ret = page_to_pfn(page); - up_read(¤t->mm->mmap_sem); - return ret; + /* gup me one page at this address please! */ + if (get_user_pages_fast(virtpfn << PAGE_SHIFT, 1, write, &page) == 1) + return page_to_pfn(page); + + /* This value indicates failure. */ + return -1UL; } /*H:340 Converting a Guest page table entry to a shadow (ie. real) page table @@ -174,7 +167,7 @@ static pte_t gpte_to_spte(struct lg_cpu *cpu, pte_t gpte, int write) /*H:460 And to complete the chain, release_pte() looks like this: */ static void release_pte(pte_t pte) { - /* Remember that get_user_pages() took a reference to the page, in + /* Remember that get_user_pages_fast() took a reference to the page, in * get_pfn()? We have to put it back now. */ if (pte_flags(pte) & _PAGE_PRESENT) put_page(pfn_to_page(pte_pfn(pte))); |