Re: [PATCH 1/3] accel/tcg: Fix unaligned stores to s390x low-address-protected lowcore

[Richard Henderson <richard.henderson@linaro.org>]

On 7/12/22 00:26, Ilya Leoshkevich wrote:
> If low-address-protection is active, unaligned stores to non-protected
> parts of lowcore lead to protection exceptions. The reason is that in
> such cases tlb_fill() call in store_helper_unaligned() covers
> [0, addr + size) range, which contains the protected portion of
> lowcore. This range is too large.
> 
> The most straightforward fix would be to make sure we stay within the
> original [addr, addr + size) range. However, if an unaligned access
> affects a single page, we don't need to call tlb_fill() in
> store_helper_unaligned() at all, since it would be identical to
> the previous tlb_fill() call in store_helper(), and therefore a no-op.
> If an unaligned access covers multiple pages, this situation does not
> occur.
> 
> Therefore simply skip TLB handling in store_helper_unaligned() if we
> are dealing with a single page.
> 
> Fixes: 2bcf018340cb ("s390x/tcg: low-address protection support")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Queueing to tcg-next.  I'll let the test case go through s390x.


r~