Re: [Xen-devel] [PATCH V2] Xen: ARM: Zero reserved fields of xatp before making hypervisor call

[Juergen Gross <jgross@xxxxxxxx>]

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@xxxxxxxxxxxxxx>
> ---
> 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.


Juergen

>               r = &resources[i];
>               nr = DIV_ROUND_UP(resource_size(r), XEN_PAGE_SIZE);
>               if ((resource_type(r) != IORESOURCE_MEM) || (nr == 0))
> @@ -87,9 +91,7 @@ static int xen_map_device_mmio(const struct resource 
> *resources,
>                       idxs[j] = XEN_PFN_DOWN(r->start) + j;
>               }
>  
> -             xatp.domid = DOMID_SELF;
>               xatp.size = nr;
> -             xatp.space = XENMAPSPACE_dev_mmio;
>  
>               set_xen_guest_handle(xatp.gpfns, gpfns);
>               set_xen_guest_handle(xatp.idxs, idxs);
> 


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel