On 22/07/2024 13:58, Jan Beulich wrote:
On 21.07.2024 10:51, Julien Grall wrote:
On 12/07/2024 17:22, Oleksii Kurochko wrote:
+inline pte_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr)
+{
+ /* there is no attr field in RISC-V's pte */
+ (void) attr;
Surely you have a way to say indicate whether an entry is readable/writable?
I'm puzzled by this question. The sole outlier in Arm code is pmap.h, in
passing PAGE_HYPERVISOR_RW to this function when all others pass memory
types (MT_*). > Afaics only the low three bits are then used in the
function, discarding access control bits altogether. R/W access appears
to be implied.
Arm is not exempt of odd interfaces. However, from just this patch, it
is not clear why RISC-V would continue to use the same appropach if the
attributes doesn't exist.
Looking at the rest of the series, it seems to be because we wanted to
have a generic page-table code. If there are a desire to continue
towards this direction, then I would assume we would need a arch
specific way to set the read/write bit.
At which point it makes a lot more sense to push setting the access bits
in mfn_to_xen_entry().
Even if we don't do any code consolidation, I think it is odd for Arm
that a caller will assume mfn_to_xen_entry() will always return a
read-writable page and update as necessary. It would be nicer to push
this decision to mfn_to_xen_entry().
Cheers,
--
Julien Grall
