Re: [PATCH v2 0/3] accel/tcg: Alternate fix for #1866

[Philippe Mathieu-Daudé]

On 15/9/23 18:32, Richard Henderson wrote:
> Supercedes: 20230914174436.1597356-1-richard.henderson@linaro.org
> ("[PATCH 0/6] accel/tcg: Always require can_do_io (#1866)")

Patches 1-4 (5?) are cleanups although, isn't it?

> An alternate fix for #1866 without touching can_do_io, and is
> perhaps a bit cleaner and clearer.
>
> Instead, the current cpu checks whether an address space update
> is required on each entry to the slow path.  This certainly
> catches all i/o.  It easily works for the sequential case of
> two i/o, the first of which changes the address space and the
> second of which requires the new address space.
>
> I've done a tiny bit of performance testing between the two
> solutions and it seems to be a wash.  So now it's simply a
> matter of cleanliness.
>
>
> r~
>
>
> Richard Henderson (3):
>    softmmu: Use cpu->created in tcg_commit
>    softmmu: Introduce AddressSpaceDispatch generation numbers
>    softmmu: Introduce cpu_address_space_sync
>
>   include/exec/memory.h |  6 ++++++
>   accel/tcg/cputlb.c    |  2 ++
>   softmmu/physmem.c     | 46 ++++++++++++++++++++++++++++++++++++-------
>   3 files changed, 47 insertions(+), 7 deletions(-)