On 05/29/2018 02:22 PM, Oleksandr Andrushchenko wrote:
On 05/29/2018 09:04 PM, Boris Ostrovsky wrote:
On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:
@@ -463,11 +457,6 @@ static enum bp_state increase_reservation(unsigned long nr_pages) int rc; unsigned long i; struct page *page; - struct xen_memory_reservation reservation = { - .address_bits = 0, - .extent_order = EXTENT_ORDER, - .domid = DOMID_SELF - }; if (nr_pages > ARRAY_SIZE(frame_list)) nr_pages = ARRAY_SIZE(frame_list); @@ -486,9 +475,7 @@ static enum bp_state increase_reservation(unsigned long nr_pages) page = balloon_next_page(page); } - set_xen_guest_handle(reservation.extent_start, frame_list); - reservation.nr_extents = nr_pages; - rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); + rc = xenmem_reservation_increase(nr_pages, frame_list); if (rc <= 0) return BP_EAGAIN; @@ -496,29 +483,7 @@ static enum bp_state increase_reservation(unsigned long nr_pages) page = balloon_retrieve(false); BUG_ON(page == NULL); -#ifdef CONFIG_XEN_HAVE_PVMMU - /* - * We don't support PV MMU when Linux and Xen is using - * different page granularity. - */ - BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
- if (!xen_feature(XENFEAT_auto_translated_physmap)) { - unsigned long pfn = page_to_pfn(page);
- set_phys_to_machine(pfn, frame_list[i]);
- /* Link back into the page tables if not highmem. */ - if (!PageHighMem(page)) { - int ret; - ret = HYPERVISOR_update_va_mapping( - (unsigned long)__va(pfn << PAGE_SHIFT), - mfn_pte(frame_list[i], PAGE_KERNEL), - 0); - BUG_ON(ret); - } - } -#endif + xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
Can you make a single call to xenmem_reservation_va_mapping_update(rc, ...)? You need to keep track of pages but presumable they can be put into an array (or a list). In fact, perhaps we can have balloon_retrieve() return a set of pages.
This is actually how it is used later on for dma-buf, but I just didn't want to alter original balloon code too much, but this can be done, in order of simplicity:
- Similar to frame_list, e.g. static array of struct page* of size
ARRAY_SIZE(frame_list): more static memory is used, but no allocations
- Allocated at run-time with kcalloc: allocation can fail
If this is called in freeing DMA buffer code path or in error path then we shouldn't do it.
- Make balloon_retrieve() return a set of pages: will require
list/array allocation and handling, allocation may fail, balloon_retrieve prototype change
balloon pages are strung on the lru list. Can we keep have balloon_retrieve return a list of pages on that list?
-boris
Could you please tell which of the above will fit better?