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SubjectRe: [Xen-devel] [PATCH 1/4] xen: re-introduce support for grant v2 interface
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On 12/09/17 17:41, Boris Ostrovsky wrote:
>
>> +int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
>> + unsigned long max_nr_gframes,
>> + grant_status_t **__shared)
>> +{
>> + grant_status_t *shared = *__shared;
>> + unsigned long addr;
>> + unsigned long i;
>> +
>> + if (shared == NULL)
>> + *__shared = shared = gnttab_status_vm_area.area->addr;
>> +
>> + addr = (unsigned long)shared;
>> +
>> + for (i = 0; i < nr_gframes; i++) {
>> + set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
>> + mfn_pte(frames[i], PAGE_KERNEL));
>> + addr += PAGE_SIZE;
>> + }
>> +
>> + return 0;
>> +}
>
> This looks pretty much identical to arch_gnttab_map_shared() except for
> gnttab_shared_vm_area vs. gnttab_status_vm_area,which can be passed in
> as a parameter.
>
>> +
>> void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
>> {
>> + pte_t **ptes;
>> unsigned long addr;
>> unsigned long i;
>>
>> + if (shared == gnttab_status_vm_area.area->addr)
>> + ptes = gnttab_status_vm_area.ptes;
>> + else
>> + ptes = gnttab_shared_vm_area.ptes;
>> +
>> addr = (unsigned long)shared;
>>
>> for (i = 0; i < nr_gframes; i++) {
>> - set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
>> - __pte(0));
>> + set_pte_at(&init_mm, addr, ptes[i], __pte(0));
>> addr += PAGE_SIZE;
>> }
>
> And this too looks like can be factored out (to something like
> arch_update_gnttab()). But perhaps not in this patch.
>
>> }
>> @@ -102,12 +129,35 @@ static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
>> return 0;
>> }
>>
>> -int arch_gnttab_init(unsigned long nr_shared)
>> +static void arch_gnttab_vfree(struct gnttab_vm_area *area)
>> {
>> + free_vm_area(area->area);
>> + kfree(area->ptes);
>> +}
>
> Not sure there is need for this routine. It is used only once.
>
> Also, as an overall comment -- It feels like there may be too many
> BUG_ON()s.

This patch is mostly a revert of David's patch removing grant v2 support
with just very few adaptions. I wanted to keep it as similar to the
former grant v2 support as possible.


Juergen

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