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Re: [Xen-devel] [PATCH 03/14] xen/x86: Make mfn_to_gfn typesafe
Hi,
On 10/05/2019 14:25, Julien Grall wrote:
On 10/05/2019 14:24, Jan Beulich wrote:
On 10.05.19 at 15:02, <julien.grall@xxxxxxx> wrote:
On 10/05/2019 12:35, Jan Beulich wrote:
On 07.05.19 at 17:14, <julien.grall@xxxxxxx> wrote:
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -474,7 +474,8 @@ static inline void trace_resync(int event, mfn_t gmfn)
if ( tb_init_done )
{
/* Convert gmfn to gfn */
- unsigned long gfn = mfn_to_gfn(current->domain, gmfn);
+ unsigned long gfn = gfn_x(mfn_to_gfn(current->domain, gmfn));
+
__trace_var(event, 0/*!tsc*/, sizeof(gfn), &gfn);
}
Can't you use gfn_t here, and hence avoid the gfn_x()? Same again further
down.
Because __trace_var will export the value to the guest. I wasn't sure
whether we
can safely consider that gfn_t is exactly the same as unsigned long in
debug-build.
Hmm, well - see the definition of gfn_t. George, what do you think?
I know what's the current definition. My point is we never made that assumption
before. In all honesty, sure assumption would definitely help in a few places,
but I think we ought to safeguard with BUILD_BUG(...).
George, do you have any opinions?
Cheers,
--
Julien Grall
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