Re: [Xen-devel] [PATCH 2/4] xen/public: arm: Rework __guest_handle_param*

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-11-02 at 15:39 +0000, Julien Grall wrote:
> On 02/11/15 15:35, Ian Campbell wrote:
> > On Mon, 2015-11-02 at 15:24 +0000, Julien Grall wrote:
> > > Hi Stefano,
> > > 
> > > On 02/11/15 15:19, Stefano Stabellini wrote:
> > > > On Fri, 30 Oct 2015, Julien Grall wrote:
> > > > > __guest_handle_param is used to represent a guest pointer stored
> > > > > pass
> > > > > as
> > > > > an hypercall parameters. They are the same size as the native
> > > > > register
> > > > > for the architecture. It will be 32-bit on ARM32 and 64-bit on
> > > > > ARM64.
> > > > > 
> > > > > As the __guest_handle_param will always be the size of a native
> > > > > pointer, there is no need to have a union with an unsigned long.
> > > > > 
> > > > > Note that unsigned long may be not equivalent to the size of a
> > > > > pointer
> > > > > on ARM64. It depends whether the software is build using the LP64
> > > > > or
> > > > > LLP64 data model. The size of an unsigned long in the latter will
> > > > > be
> > > > > 32-bit.
> > > > > 
> > > > > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > > > 
> > > > Obviously this is going to break set_xen_guest_handle_raw. I don't
> > > > think
> > > > this cannot be committed separately to the change to
> > > > set_xen_guest_handle_raw.
> > > 
> > > Well, all the usage of set_xen_guest_handle_raw within the hypervisor
> > > are in compat and kexec which is not built for ARM.
> > 
> > Shall we drop it from ARM then?
> 
> No. Sorry it wasn't clear on my previous mail, I was only speaking about
> the usage of set_xen_guest_handle_raw on a XEN_GUEST_HANDLE_PARAM.
> 
> set_xen_guest_handle_raw is used by the guest/toolstack to set a pointer
> in a structure. All those usages are done with a GUEST_HANDLE and not a
> GUEST_HANDLE_PARAM.

Ah yes, if I'd have thought about it I could have worked that out myself,
sorry.

Ian.

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