On 11/10/2021 13:41, Bertrand Marquis wrote:
Hi Jan,
Hi Bertrand,
As Rahul is on leave, I will answer you and make the changes needed.
On 7 Oct 2021, at 14:43, Jan Beulich <jbeul...@suse.com> wrote:
Independent of this - is bare metal Arm enforcing this same
alignment restriction (unconditionally)? Iirc on x86 we felt we'd
better synthesize misaligned accesses.
Unaligned IO access could be synthesise also on arm to but I would
rather not make such a change now without testing it (and there is
also a question of it making sense).
Yes it makes sense. I actually have an item in my TODO list to forbid
unaligned access because they should not happen on any device we
currently emulate.
Although, I am not aware of any issue other than the guest would shoot
itself in the foot if this happens.
So if it is ok with you I will keep that check and discuss it with Rahul
when he is back. I will add a comment in the code to make that clear.
I am OK with it.
[...]
Throughout this series I haven't been able to spot where the HAS_VPCI
Kconfig symbol would get selected. Hence I cannot tell whether all of
this is Arm64-specific. Otherwise I wonder whether size 8 actually
can occur on Arm32.
Dabt.size could be 3 even on ARM32 but we should not allow 64bit
access on mmio regions on arm32.
Hmmm... Looking at the Armv7 and Armv8 spec, ldrd/strd (64-bit read)
would not present a valid ISV. So I think it is not be possible to have
dabt.size = 3 for 32-bit domain. But I agree we probably want to harden
the code.
So I will surround this code with ifdef CONFIG_ARM_64 and add a test
for len > 4 to prevent this case on 32bit.
To be completely right we should disable this also for 32bit guests but
this change would be a bit more invasive.
I think the following should be sufficient:
if ( is_domain_32bit_domain() && len > 4 )
return ...;
Cheers,
--
Julien Grall
