On 03/16/2017 05:48 AM, Paolo Bonzini wrote:
On 02/03/2017 16:17, Brijesh Singh wrote:+static struct page **sev_pin_memory(unsigned long uaddr, unsigned long ulen, + unsigned long *n) +{ + struct page **pages; + int first, last; + unsigned long npages, pinned; + + /* Get number of pages */ + first = (uaddr & PAGE_MASK) >> PAGE_SHIFT; + last = ((uaddr + ulen - 1) & PAGE_MASK) >> PAGE_SHIFT; + npages = (last - first + 1); + + pages = kzalloc(npages * sizeof(struct page *), GFP_KERNEL); + if (!pages) + return NULL; + + /* pin the user virtual address */ + down_read(¤t->mm->mmap_sem); + pinned = get_user_pages_fast(uaddr, npages, 1, pages); + up_read(¤t->mm->mmap_sem);get_user_pages_fast, like get_user_pages_unlocked, must be called without mmap_sem held.
Sure.
+ if (pinned != npages) { + printk(KERN_ERR "SEV: failed to pin %ld pages (got %ld)\n", + npages, pinned); + goto err; + } + + *n = npages; + return pages; +err: + if (pinned > 0) + release_pages(pages, pinned, 0); + kfree(pages); + + return NULL; +} + /* the array of pages returned by get_user_pages() is a page-aligned + * memory. Since the user buffer is probably not page-aligned, we need + * to calculate the offset within a page for first update entry. + */ + offset = uaddr & (PAGE_SIZE - 1); + len = min_t(size_t, (PAGE_SIZE - offset), ulen); + ulen -= len; + + /* update first page - + * special care need to be taken for the first page because we might + * be dealing with offset within the page + */No need to special case the first page; just set "offset = 0" inside the loop after the first iteration.
Will do. -Brijesh
