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

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