Re: [Xen-devel] [PATCH 02/13] xen/grant-table: Move xlated_setup_gnttab_pages to common place

[David Vrabel <david.vrabel-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>]

On 18/11/15 04:32, Shannon Zhao wrote:
> On 2015/11/18 0:02, David Vrabel wrote:
>> On 17/11/15 09:57, shannon.zhao-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org wrote:
>>> From: Shannon Zhao <shannon.zhao-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>>>
>>> Move xlated_setup_gnttab_pages to common place, so it can be reused by
>>> ARM to setup grant table when booting with ACPI.
>> [...]
>>> --- a/drivers/xen/grant-table.c
>>> +++ b/drivers/xen/grant-table.c
>>> @@ -664,6 +664,55 @@ int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
>>>  }
>>>  EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
>>>  
>>> +int __init xlated_setup_gnttab_pages(void)
>>> +{
>>> +	struct page **pages;
>>> +	xen_pfn_t *pfns;
>>> +	void *vaddr;
>>> +	int rc;
>>> +	unsigned int i;
>>> +	unsigned long nr_grant_frames = gnttab_max_grant_frames();
>>> +
>>> +	BUG_ON(nr_grant_frames == 0);
>>> +	pages = kcalloc(nr_grant_frames, sizeof(pages[0]), GFP_KERNEL);
>>> +	if (!pages)
>>> +		return -ENOMEM;
>>> +
>>> +	pfns = kcalloc(nr_grant_frames, sizeof(pfns[0]), GFP_KERNEL);
>>> +	if (!pfns) {
>>> +		kfree(pages);
>>> +		return -ENOMEM;
>>> +	}
>>> +	rc = alloc_xenballooned_pages(nr_grant_frames, pages, 0 /* lowmem */);
>>> +	if (rc) {
>>> +		pr_warn("%s Couldn't balloon alloc %ld pfns rc:%d\n", __func__,
>>> +			nr_grant_frames, rc);
>>> +		kfree(pages);
>>> +		kfree(pfns);
>>> +		return rc;
>>> +	}
>>> +	for (i = 0; i < nr_grant_frames; i++)
>>> +		pfns[i] = page_to_pfn(pages[i]);
>>> +
>>> +	vaddr = vmap(pages, nr_grant_frames, 0, PAGE_KERNEL);
>>> +	if (!vaddr) {
>>> +		pr_warn("%s Couldn't map %ld pfns rc:%d\n", __func__,
>>> +			nr_grant_frames, rc);
>>> +		free_xenballooned_pages(nr_grant_frames, pages);
>>> +		kfree(pages);
>>> +		kfree(pfns);
>>> +		return -ENOMEM;
>>> +	}
>>> +	kfree(pages);
>>
>> Can you move most of this function into drivers/xen/xlate_mmu.c in a
>> function like:
>>
>> /**
>>  * xen_xlate_map_ballooned_pages - map a new set of ballooned pages
>>  * count: number of GFNs.
>>  * pages: returns the array of (now) ballooned pages.
>>  * gfns: returns the array of corresponding GFNs.
>>  * virt: returns the virtual address of the mapped region.
>>  *
>>  * This allocate a set of ballooned pages and maps them into the
>>  * kernel's address space.
>>  */
>> void *xen_xlate_map_ballooned_pages(
>>     unsigned int count,
>>     struct page **pages,
>>     xen_pfn_t **gfns);
>>
> Sure, but the parameter "pages" is not necessary I think, since the
> pages has been freed in the function and it doesn't need in
> xen_auto_xlat_grant_frames either. Right?

Yes.

David