Messages in this thread | | | Subject | Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory | From | Julien Grall <> | Date | Thu, 1 Jun 2017 15:01:09 +0100 |
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Hi Boris,
On 01/06/17 14:33, Boris Ostrovsky wrote: > On 06/01/2017 08:50 AM, Julien Grall wrote: >> Hi Boris, >> >> On 31/05/17 14:54, Boris Ostrovsky wrote: >>> On 05/31/2017 09:03 AM, Julien Grall wrote: >>>> Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page >>>> granularity" did >>>> not go far enough to support 64KB in mmap_batch_fn. >>>> >>>> The variable 'nr' is the number of 4KB chunk to map. However, when >>>> Linux >>>> is using 64KB page granularity the array of pages >>>> (vma->vm_private_data) >>>> contain one page per 64KB. Fix it by incrementing st->index correctly. >>>> >>>> Furthermore, st->va is not correctly incremented as PAGE_SIZE != >>>> XEN_PAGE_SIZE. >>>> >>>> Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page >>>> granularity") >>>> CC: stable@vger.kernel.org >>>> Reported-by: Feng Kan <fkan@apm.com> >>>> Signed-off-by: Julien Grall <julien.grall@arm.com> >>>> --- >>>> drivers/xen/privcmd.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c >>>> index 7a92a5e1d40c..feca75b07fdd 100644 >>>> --- a/drivers/xen/privcmd.c >>>> +++ b/drivers/xen/privcmd.c >>>> @@ -362,8 +362,8 @@ static int mmap_batch_fn(void *data, int nr, >>>> void *state) >>>> st->global_error = 1; >>>> } >>>> } >>>> - st->va += PAGE_SIZE * nr; >>>> - st->index += nr; >>>> + st->va += XEN_PAGE_SIZE * nr; >>>> + st->index += nr / XEN_PFN_PER_PAGE; >>>> >>>> return 0; >>>> } >>> >>> >>> Are we still using PAGE_MASK for xen_remap_domain_gfn_array()? >> >> Do you mean in the xen_xlate_remap_gfn_array implementation? If so >> there are no use of PAGE_MASK as the code has been converted to >> support 64K page granularity. >> >> If you mean the x86 version of xen_remap_domain_gfn_array, then we >> don't really care as x86 only use 4KB page granularity. > > > I meant right above the change that you made. Should it also be replaced > with XEN_PAGE_MASK? (Sorry for being unclear.)
Oh. The code in xen_remap_domain_gfn_array is relying on st->va to be page aligned. So I think we want to keep PAGE_MASK here.
Cheers,
-- Julien Grall
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