+cc target and migration maintainers
On 9/6/25 07:18, Richard Henderson wrote:
It is too easy to mis-use tb_flush(). For instance, because of
the cpu argument, some parts assumed that it needed to call the
global flush function for every cpu. It is easy to forget that
the flush is not complete when the call returns: we have merely
queued work to the cpu run loop.
(Phil, I suspect this second case is what's biting split-accel.)
So: remove tb_flush and expose only the core as tb_flush__exclusive,
to be used only when we are already within an exclusive context.
In some cases (gdbstub, alpha, riscv, ppc spapr), we can eliminate
the need for tb_flush completely.
Lightly tested so far, and I'm off on holiday next, but I thought
this might help others working on split-accel in the meantime.
r~
Richard Henderson (11):
gdbstub: Remove tb_flush uses
accel/tcg: Split out tb_flush__exclusive
target/alpha: Simplify call_pal implementation
target/riscv: Record misa_ext in TCGTBCPUState.cs_base
accel/tcg: Move post-load tb_flush to vm_change_state hook
hw/ppc/spapr: Use tb_invalidate_phys_range in h_page_init
linux-user: Use tb_flush_exclusive to start second thread
plugins: Use tb_flush__exclusive
accel/tcg: Introduce EXCP_TB_FLUSH
accel/tcg: Use EXCP_TB_FLUSH in tb_gen_code
accel/tcg: Remove tb_flush
include/exec/cpu-common.h | 1 +
include/exec/tb-flush.h | 18 +++++++---------
target/alpha/helper.h | 1 -
accel/tcg/tb-maint.c | 38 +++++++--------------------------
accel/tcg/tcg-accel-ops-mttcg.c | 7 ++++++
accel/tcg/tcg-accel-ops-rr.c | 9 ++++++--
accel/tcg/tcg-all.c | 21 ++++++++++++++++++
accel/tcg/translate-all.c | 5 +----
gdbstub/system.c | 4 ----
gdbstub/user.c | 3 ---
hw/core/cpu-system.c | 8 -------
hw/ppc/spapr_hcall.c | 4 ++--
linux-user/mmap.c | 4 ++--
linux-user/syscall.c | 2 +-
plugins/core.c | 6 ++----
plugins/loader.c | 2 +-
target/alpha/sys_helper.c | 6 ------
target/alpha/translate.c | 21 ++++++------------
target/riscv/csr.c | 3 ---
target/riscv/tcg/tcg-cpu.c | 3 ++-
20 files changed, 69 insertions(+), 97 deletions(-)
