Re: [PATCH] target/arm: Avoid target_ulong for physical address lookups

[Arnd Bergmann]

On Mon, Sep 23, 2024, at 09:22, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> target_ulong is typedef'ed as a 32-bit integer when building the
> qemu-system-arm target, and this is smaller than the size of an
> intermediate physical address when LPAE is being used.
>
> Given that Linux may place leaf level user page tables in high memory
> when built for LPAE, the kernel will crash with an external abort as
> soon as it enters user space when running with more than ~3 GiB of
> system RAM.
>
> So replace target_ulong with hwaddr in places where it may carry an
> address value that is not representable in 32 bits.
>
> Fixes: f3639a64f602ea ("target/arm: Use softmmu tlbs for page table walking")
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Thanks for the fix, I now confirmed that this addresses the problem.

I had looked at this code before and got confused thinking that these
addresses were ok as 32-bit wide integers.

      Arnd