On 03/16/2018 12:14 PM, jglisse@xxxxxxxxxx wrote:
> From: Jérôme Glisse <jglisse@xxxxxxxxxx>
>
> Special vma (one with any of the VM_SPECIAL flags) can not be access by
> device because there is no consistent model accross device drivers on
> those vma and their backing memory.
>
> This patch directly use hmm_range struct for hmm_pfns_special() argument
> as it is always affecting the whole vma and thus the whole range.
>
> It also make behavior consistent after this patch both hmm_vma_fault()
> and hmm_vma_get_pfns() returns -EINVAL when facing such vma. Previously
> hmm_vma_fault() returned 0 and hmm_vma_get_pfns() return -EINVAL but
> both were filling the HMM pfn array with special entry.
>
Hi Jerome,
This seems correct.
<snip>
> @@ -486,6 +478,14 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
> return 0;
> }
>
> +static void hmm_pfns_special(struct hmm_range *range)
> +{
> + unsigned long addr = range->start, i = 0;
> +
> + for (; addr < range->end; addr += PAGE_SIZE, i++)
> + range->pfns[i] = HMM_PFN_SPECIAL;
> +}
Silly nit: the above would read more naturally, like this:
unsigned long addr, i = 0;
for (addr = range->start; addr < range->end; addr += PAGE_SIZE, i++)
range->pfns[i] = HMM_PFN_SPECIAL;
Either way,
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
thanks,
--
John Hubbard
NVIDIA
