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.
> + 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.
Paolo
> + data->handle = sev_get_handle(kvm);
> + data->length = len;
> + data->address = __sev_page_pa(inpages[0]) + offset;
> + ret = sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE_DATA,
> + data, &argp->error);
> + if (ret)
> + goto err_3;
> +
> + /* update remaining pages */
> + for (i = 1; i < nr_pages; i++) {
> +
> + len = min_t(size_t, PAGE_SIZE, ulen);
> + ulen -= len;
> + data->length = len;
> + data->address = __sev_page_pa(inpages[i]);
> + ret = sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE_DATA,
> + data, &argp->error);
> + if (ret)
> + goto err_3;
> + }
