Re: [Xen-devel] getting a 32-bit mfn from a 32-on-64 HVM guest

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 20/06/2010 18:45, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> What is the "proper" way to ensure that the cmfn
> is properly truncated for a 32-bit HVM guest
> without truncating it for a 64-bit guest?  I
> have used is_pv_32on64_vcpu()... is there an equivalent
> for HVM? Or do I need to do something entirely different?

See the x86_64 version of arch/x86/hvm/hvm.c:hvm_do_hypercall() which uses
hvm_guest_x86_mode() to get the 'bitness' of the HVM-guest caller. You
should do the same, probably. Or even have a compat shim around your
hypercall same as others which have differences between 32- and 64-bit
struct layouts, and have the dispatch tables in hvm.c (HVM callers) and
entry.S (PV callers) dispatch to the correct entry point for the bitness of
the caller.

 -- Keir



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