Re: [PATCH v5 3/3] xen: add helpers to allocate unpopulated memory

On 01.09.20 16:45, Roger Pau Monné wrote:

On Tue, Sep 01, 2020 at 10:33:26AM +0200, Roger Pau Monne wrote:

...

+static int fill_list(unsigned int nr_pages) +{

• 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_GENERIC;
• pgmap->res.name = "Xen scratch";
• 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);
  

• if (ret < 0) {

• pr_err("Cannot allocate new IOMEM resource\n");
  

• kfree(pgmap);
  

• return ret;
  

• }
• nid = memory_add_physaddr_to_nid(pgmap->res.start);

I think this is not needed ...

...

+#ifdef CONFIG_XEN_HAVE_PVMMU

•    /*
  

•     * 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);

... and NUMA_NO_NODE should be used here instead, as this memory is just fictitious space to map foreign memory, and shouldn't be related to any NUMA node.

The following chunk should be folded in, or I can resend.

I can fold it in.

Juergen