Hi Paul,
On 27/10/17 16:19, Paul Durrant wrote:
-----Original Message-----
From: Julien Grall [mailto:julien.gr...@linaro.org]
Sent: 27 October 2017 12:46
To: Jan Beulich <jbeul...@suse.com>; Paul Durrant
<paul.durr...@citrix.com>
Cc: Julien Grall <julien.gr...@arm.com>; Andrew Cooper
<andrew.coop...@citrix.com>; Wei Liu <wei.l...@citrix.com>; George
Dunlap <george.dun...@citrix.com>; Ian Jackson <ian.jack...@citrix.com>;
Stefano Stabellini <sstabell...@kernel.org>; xen-de...@lists.xenproject.org;
Konrad Rzeszutek Wilk <konrad.w...@oracle.com>; Daniel De Graaf
<dgde...@tycho.nsa.gov>; Tim (Xen.org) <t...@xen.org>
Subject: Re: [Xen-devel] [PATCH v12 05/11] x86/mm: add
HYPERVISOR_memory_op to acquire guest resources
Hi,
On 26/10/17 16:39, Jan Beulich wrote:
On 26.10.17 at 17:32, <julien.gr...@linaro.org> wrote:
On 26/10/17 16:26, Jan Beulich wrote:
On 17.10.17 at 15:24, <paul.durr...@citrix.com> wrote:
+ /* IN/OUT - If the tools domain is PV then, upon return, frame_list
+ * will be populated with the MFNs of the resource.
+ * If the tools domain is HVM then it is expected that, on
+ * entry, frame_list will be populated with a list of GFNs
+ * that will be mapped to the MFNs of the resource.
+ * If -EIO is returned then the frame_list has only been
+ * partially mapped and it is up to the caller to unmap all
+ * the GFNs.
+ * This parameter may be NULL if nr_frames is 0.
+ */
+ XEN_GUEST_HANDLE(xen_ulong_t) frame_list;
This is still xen_ulong_t, which I can live with, but then you shouldn't
copy into / out of arrays of other types in acquire_resource() (the
more that this is common code, and iirc xen_ulong_t and
unsigned long aren't the same thing on ARM32).
xen_ulong_t is always 64-bit on Arm (32-bit and 64-bit). But shouldn't
we use xen_pfn_t here?
I had put this question up earlier, but iirc Paul didn't like it.
I'd like to understand why Paul doesn't like it. We should never assume
that a frame fit in xen_ulong_t. xen_pfn_t was exactly introduced for
that purpose.
My reservation is whether xen_pfn_t is intended to hold either gfns or mfns,
since this hypercall uses the same array for both. If it suitable then I am
happy to change it, but Andrew led me to believe otherwise.
Looking at the public hearders, xen_pfn_t is been used for both MFN (see
xenpf_add_memtype) and GFN (see gnttab_setup_table).
So I think it would be fine to do the same here.
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
