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SubjectRe: [PATCH V2] Xen: ARM: Zero reserved fields of xatp before making hypervisor call
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Hi Stefano,

On 03/01/17 18:03, Stefano Stabellini wrote:
> On Mon, 2 Jan 2017, Juergen Gross wrote:
>> On 28/12/16 01:47, Jiandi An wrote:
>>> Ensure all reserved fields of xatp are zero before making
>>> hypervisor call to XEN in xen_map_device_mmio().
>>> xenmem_add_to_physmap_one() in XEN fails the mapping request if
>>> extra.res reserved field in xatp is not zero for XENMAPSPACE_dev_mmio
>>> request.
>>>
>>> Signed-off-by: Jiandi An <anjiandi@codeaurora.org>
>>> ---
>>> Changed zeroing xatp to a static initialization
>>> of .domid and .space for xatp.
>>>
>>> drivers/xen/arm-device.c | 8 +++++---
>>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/xen/arm-device.c b/drivers/xen/arm-device.c
>>> index 778acf8..85dd20e 100644
>>> --- a/drivers/xen/arm-device.c
>>> +++ b/drivers/xen/arm-device.c
>>> @@ -58,9 +58,13 @@ static int xen_map_device_mmio(const struct resource *resources,
>>> xen_pfn_t *gpfns;
>>> xen_ulong_t *idxs;
>>> int *errs;
>>> - struct xen_add_to_physmap_range xatp;
>>>
>>> for (i = 0; i < count; i++) {
>>> + struct xen_add_to_physmap_range xatp = {
>>> + .domid = DOMID_SELF,
>>> + .space = XENMAPSPACE_dev_mmio
>>> + };
>>> +
>>
>> I still don't see the need to re-initialize the input parts of xatp
>> on each loop iteration unless you can show the need for it (e.g. a
>> buggy hypervisor version not conforming to the interface specification).
>>
>> OTOH I don't feel really strong about it and let Stefano being the
>> maintainer for the ARM parts decide.
>
> I don't feel strongly about this either - I think this patch is good
> enough. I'll apply to xentip.

I think this patch should be backported to stable trees because the
issue could appear depending on the compiler.

Cheers,

--
Julien Grall

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