On 7/24/20 10:34 AM, David Hildenbrand wrote:
CCing Dan
On 24.07.20 14:42, Roger Pau Monne wrote:
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c new file mode 100644 index 000000000000..aaa91cefbbf9 --- /dev/null +++ b/drivers/xen/unpopulated-alloc.c @@ -0,0 +1,222 @@
- */
+#include <linux/errno.h> +#include <linux/gfp.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/memremap.h> +#include <linux/slab.h>
+#include <asm/page.h>
+#include <xen/page.h> +#include <xen/xen.h>
+static DEFINE_MUTEX(lock); +static LIST_HEAD(list); +static unsigned int count;
+static int fill(unsigned int nr_pages)
Less generic names? How about list_lock, pg_list, pg_count, fill_pglist()? (But these are bad too, so maybe you can come up with something better)
+{
- struct dev_pagemap *pgmap;
- void *vaddr;
- unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
- int nid, ret;
- pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
- if (!pgmap)
return -ENOMEM;- pgmap->type = MEMORY_DEVICE_DEVDAX;
- pgmap->res.name = "XEN SCRATCH";
Typically iomem resources only capitalize first letters.
- pgmap->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- ret = allocate_resource(&iomem_resource, &pgmap->res,
alloc_pages * PAGE_SIZE, 0, -1,PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
Are we not going to end up with a whole bunch of "Xen scratch" resource ranges for each miss in the page list? Or do we expect them to get merged?
- if (ret < 0) {
pr_err("Cannot allocate new IOMEM resource\n");kfree(pgmap);return ret;- }
- nid = memory_add_physaddr_to_nid(pgmap->res.start);
Should we consider page range crossing node boundaries?
+#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);
/** memremap will build page tables for the new memory so* the p2m must contain invalid entries so the correct* non-present PTEs will be written.** If a failure occurs, the original (identity) p2m entries* are not restored since this region is now known not to* conflict with any devices.*/- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
xen_pfn_t pfn = PFN_DOWN(pgmap->res.start);for (i = 0; i < alloc_pages; i++) {if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {pr_warn("set_phys_to_machine() failed, no memory added\n");release_resource(&pgmap->res);kfree(pgmap);return -ENOMEM;}}- }
+#endif
- vaddr = memremap_pages(pgmap, nid);
- if (IS_ERR(vaddr)) {
pr_err("Cannot remap memory range\n");release_resource(&pgmap->res);kfree(pgmap);return PTR_ERR(vaddr);- }
- for (i = 0; i < alloc_pages; i++) {
struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));list_add(&pg->lru, &list);count++;- }
- return 0;
+}
+/**
- xen_alloc_unpopulated_pages - alloc unpopulated pages
- @nr_pages: Number of pages
- @pages: pages returned
- @return 0 on success, error otherwise
- */
+int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages) +{
- unsigned int i;
- int ret = 0;
- mutex_lock(&lock);
- if (count < nr_pages) {
ret = fill(nr_pages);
(nr_pages - count) ?
if (ret)goto out;- }
- for (i = 0; i < nr_pages; i++) {
struct page *pg = list_first_entry_or_null(&list, struct page,lru);BUG_ON(!pg);list_del(&pg->lru);count--;pages[i] = pg;+#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)) {ret = xen_alloc_p2m_entry(page_to_pfn(pg));if (ret < 0) {unsigned int j;for (j = 0; j <= i; j++) {list_add(&pages[j]->lru, &list);count++;}goto out;}}+#endif
- }
+out:
- mutex_unlock(&lock);
- return ret;
+} +EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
+#ifdef CONFIG_XEN_PV +static int __init init(void) +{
- unsigned int i;
- if (!xen_domain())
return -ENODEV;- /*
* Initialize with pages from the extra memory regions (see* arch/x86/xen/setup.c).*/
This loop will be executing only for PV guests so we can just bail out for non-PV guests here.
-boris
- for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
unsigned int j;for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {struct page *pg =pfn_to_page(xen_extra_mem[i].start_pfn + j);list_add(&pg->lru, &list);count++;}- }
- return 0;
+} +subsys_initcall(init);