On Mon, 01 Sep 2025 15:15:51 +0100, Gyujeong Jin <wlsrbwjd7232@xxxxxxxxx> wrote: > > From: gyutrange <wlsrbwjd643@xxxxxxxxx> > > VNCR/TLBI VA reconstruction currently uses bit 48 as the sign bit, > but for 48-bit virtual addresses the correct sign bit is bit 47. No, that's not the case. Bit 55 is used at all times to determine which half of the address space a VA gets resolved from. > Using 48 can mis-canonicalize addresses in the negative half and may > cause missed invalidations. > > Although VNCR_EL2 encodes other architectural fields (RESS, BADDR; > see Arm ARM D24.2.206), sign_extend64() interprets its second argument > as the index of the sign bit. Passing 48 prevents propagation of the > canonical sign bit for 48-bit VAs. > > Impact: > - Incorrect canonicalization of VAs with bit47=1 No. We are not trying to make the VA canonical. > - Potential stale VNCR pseudo-TLB entries after TLBI or MMU notifier No. The pseudo TLB is never created the first place. > - Possible incorrect translation/permissions or DoS when combined > with other issues Please explain, as "other issues" is not a valid argument. Thanks, M. -- Without deviation from the norm, progress is not possible.
