Re: [PATCH 9/9] accel/tcg: Improve can_do_io management

[Jørgen Hansen]

On 4/7/24 00:32, Richard Henderson wrote:
> We already attempted to set and clear can_do_io before the first
> and last insns, but only used the initial value of max_insns and
> the call to translator_io_start to find those insns.
> 
> Now that we track insn_start in DisasContextBase, and now that
> we have emit_before_op, we can wait until we have finished
> translation to identify the true first and last insns and emit
> the sets of can_do_io at that time.
> 
> This fixes case of a translation block which crossed a page boundary,
> and for which the second page turned out to be mmio.  In this case we
> truncate the block, and the previous logic for can_do_io could leave
> a block with a single insn with can_do_io set to false, which would
> fail an assertion in cpu_io_recompile.
> 
> Reported-by: Jørgen Hansen <Jorgen.Hansen@wdc.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   include/exec/translator.h |  1 -
>   accel/tcg/translator.c    | 45 ++++++++++++++++++++-------------------
>   2 files changed, 23 insertions(+), 23 deletions(-)

Thanks for the quick fix! I verified the patch series fixes the issue on 
my setup, and also verified that no issues were seen with full MMIO 
backing for the otherwise same test case.

Tested-by: Jørgen Hansen <Jorgen.Hansen@wdc.com>