On Thu, 01 Feb 2024 16:45:30 +0000 Alex Bennée <alex.ben...@linaro.org> wrote:
> Jonathan Cameron <jonathan.came...@huawei.com> writes: > > > On Thu, 1 Feb 2024 16:00:56 +0000 > > Peter Maydell <peter.mayd...@linaro.org> wrote: > > > >> On Thu, 1 Feb 2024 at 15:17, Alex Bennée <alex.ben...@linaro.org> wrote: > >> > > >> > Peter Maydell <peter.mayd...@linaro.org> writes: > >> > > So, that looks like: > >> > > * we call cpu_tb_exec(), which executes some generated code > >> > > * that generated code calls the lookup_tb_ptr helper to see > >> > > if we have a generated TB already for the address we're going > >> > > to execute next > >> > > * lookup_tb_ptr probes the TLB to see if we know the host RAM > >> > > address for the guest address > >> > > * this results in a TLB walk for an instruction fetch > >> > > * the page table descriptor load is to IO memory > >> > > * io_prepare assumes it needs to do a TLB recompile, because > >> > > can_do_io is clear > >> > > > >> > > I am not surprised that the corner case of "the guest put its > >> > > page tables in an MMIO device" has not yet come up :-) > >> > > > >> > > I'm really not sure how the icount handling should interact > >> > > with that... > >> > > >> > Its not just icount - we need to handle it for all modes now. That said > >> > seeing as we are at the end of a block shouldn't can_do_io be set? > >> > >> The lookup_tb_ptr helper gets called from tcg_gen_goto_tb(), > >> which happens earlier than the tb_stop callback (it can > >> happen in the trans function for branch etc insns, for > >> example). > >> > >> I think it should be OK to clear can_do_io at the start > >> of the lookup_tb_ptr helper, something like: > >> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c > >> index 977576ca143..7818537f318 100644 > >> --- a/accel/tcg/cpu-exec.c > >> +++ b/accel/tcg/cpu-exec.c > >> @@ -396,6 +396,15 @@ const void *HELPER(lookup_tb_ptr)(CPUArchState *env) > >> uint64_t cs_base; > >> uint32_t flags, cflags; > >> > >> + /* > >> + * By definition we've just finished a TB, so I/O is OK. > >> + * Avoid the possibility of calling cpu_io_recompile() if > >> + * a page table walk triggered by tb_lookup() calling > >> + * probe_access_internal() happens to touch an MMIO device. > >> + * The next TB, if we chain to it, will clear the flag again. > >> + */ > >> + cpu->neg.can_do_io = true; > >> + > >> cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); > >> > >> cflags = curr_cflags(cpu); > >> > >> -- PMM > > > > No joy. Seems like a very similar backtrace. > > > > Thread 5 "qemu-system-x86" received signal SIGABRT, Aborted. > > [Switching to Thread 0x7ffff4efe6c0 (LWP 23937)] > > __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) > > at ./nptl/pthread_kill.c:44 > > 44 ./nptl/pthread_kill.c: No such file or directory. > > (gdb) bt > > #0 __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized > > out>) at ./nptl/pthread_kill.c:44 > > #1 __pthread_kill_internal (signo=6, threadid=<optimized out>) at > > ./nptl/pthread_kill.c:78 > > #2 __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at > > ./nptl/pthread_kill.c:89 > > #3 0x00007ffff77c43b6 in __GI_raise (sig=sig@entry=6) at > > ../sysdeps/posix/raise.c:26 > > #4 0x00007ffff77aa87c in __GI_abort () at ./stdlib/abort.c:79 > > #5 0x0000555555c4d19e in cpu_abort (cpu=cpu@entry=0x5555578e0cb0, > > fmt=fmt@entry=0x555556048ee8 "cpu_io_recompile: could not find TB for > > pc=%p") at ../../cpu-target.c:373 > > #6 0x0000555555c9cb25 in cpu_io_recompile (cpu=cpu@entry=0x5555578e0cb0, > > retaddr=retaddr@entry=0) at ../../accel/tcg/translate-all.c:611 > > #7 0x0000555555c9f744 in io_prepare (retaddr=0, addr=19595790664, > > attrs=..., xlat=<optimized out>, cpu=0x5555578e0cb0, out_offset=<synthetic > > pointer>) at ../../accel/tcg/cputlb.c:1339 > > #8 do_ld_mmio_beN (cpu=0x5555578e0cb0, full=0x7ffe88012890, > > ret_be=ret_be@entry=0, addr=19595790664, size=size@entry=8, mmu_idx=4, > > type=MMU_DATA_LOAD, ra=0) at ../../accel/tcg/cputlb.c:2030 > > #9 0x0000555555ca0ecd in do_ld_8 (cpu=cpu@entry=0x5555578e0cb0, > > p=p@entry=0x7ffff4efcdd0, mmu_idx=<optimized out>, > > type=type@entry=MMU_DATA_LOAD, memop=<optimized out>, ra=ra@entry=0) at > > ../../accel/tcg/cputlb.c:2356 > > #10 0x0000555555ca332f in do_ld8_mmu (cpu=cpu@entry=0x5555578e0cb0, > > addr=addr@entry=19595790664, oi=oi@entry=52, ra=ra@entry=0, > > access_type=access_type@entry=MMU_DATA_LOAD) at > > ../../accel/tcg/cputlb.c:2439 > > #11 0x0000555555ca5e69 in cpu_ldq_mmu (ra=0, oi=52, addr=19595790664, > > env=0x5555578e3470) at ../../accel/tcg/ldst_common.c.inc:169 > > #12 cpu_ldq_le_mmuidx_ra (env=0x5555578e3470, addr=19595790664, > > mmu_idx=<optimized out>, ra=ra@entry=0) at > > ../../accel/tcg/ldst_common.c.inc:301 > > #13 0x0000555555b4b5de in ptw_ldq (in=0x7ffff4efcf10) at > > ../../target/i386/tcg/sysemu/excp_helper.c:98 > > #14 ptw_ldq (in=0x7ffff4efcf10) at > > ../../target/i386/tcg/sysemu/excp_helper.c:93 > > #15 mmu_translate (env=env@entry=0x5555578e3470, in=0x7ffff4efcfd0, > > out=0x7ffff4efcfa0, err=err@entry=0x7ffff4efcfb0) at > > ../../target/i386/tcg/sysemu/excp_helper.c:173 > > #16 0x0000555555b4c3f3 in get_physical_address (err=0x7ffff4efcfb0, > > out=0x7ffff4efcfa0, mmu_idx=0, access_type=MMU_DATA_STORE, > > addr=18386491786698339392, env=0x5555578e3470) at > > ../../target/i386/tcg/sysemu/excp_helper.c:578 > > #17 x86_cpu_tlb_fill (cs=0x5555578e0cb0, addr=18386491786698339392, > > size=<optimized out>, access_type=MMU_DATA_STORE, mmu_idx=0, > > probe=<optimized out>, retaddr=140736029817822) at > > ../../target/i386/tcg/sysemu/excp_helper.c:604 > > #18 0x0000555555ca0df9 in tlb_fill (retaddr=140736029817822, mmu_idx=0, > > access_type=MMU_DATA_STORE, size=<optimized out>, > > addr=18386491786698339392, cpu=0x7ffff4efd120) at > > ../../accel/tcg/cputlb.c:1315 > > #19 mmu_lookup1 (cpu=cpu@entry=0x5555578e0cb0, > > data=data@entry=0x7ffff4efd120, mmu_idx=0, > > access_type=access_type@entry=MMU_DATA_STORE, ra=ra@entry=140736029817822) > > at ../../accel/tcg/cputlb.c:1713 > > #20 0x0000555555ca2b71 in mmu_lookup (cpu=0x5555578e0cb0, > > addr=18386491786698339392, oi=<optimized out>, ra=140736029817822, > > type=MMU_DATA_STORE, l=0x7ffff4efd120) at ../../accel/tcg/cputlb.c:1803 > > #21 0x0000555555ca3e5d in do_st8_mmu (cpu=0x5555578e0cb0, addr=23937, > > val=18386491784638059520, oi=6, ra=140736029817822) at > > ../../accel/tcg/cputlb.c:2853 > > #22 0x00007fffa9107c63 in code_gen_buffer () > > No thats different - we are actually writing to the MMIO region here. > But the fact we hit cpu_abort because we can't find the TB we are > executing is a little problematic. > > Does ra properly point to the code buffer here? Err. How would I tell? I'll confess I have almost no idea what is going on in TCG :( Can learn but it won't be quick. J > > > #23 0x0000555555c9395b in cpu_tb_exec (cpu=cpu@entry=0x5555578e0cb0, > > itb=itb@entry=0x7fffa9107980 <code_gen_buffer+17856851>, > > tb_exit=tb_exit@entry=0x7ffff4efd718) at ../../accel/tcg/cpu-exec.c:442 > > #24 0x0000555555c93ec0 in cpu_loop_exec_tb (tb_exit=0x7ffff4efd718, > > last_tb=<synthetic pointer>, pc=<optimized out>, tb=0x7fffa9107980 > > <code_gen_buffer+17856851>, cpu=0x5555578e0cb0) at > > ../../accel/tcg/cpu-exec.c:897 > > #25 cpu_exec_loop (cpu=cpu@entry=0x5555578e0cb0, > > sc=sc@entry=0x7ffff4efd7b0) at ../../accel/tcg/cpu-exec.c:1012 > > #26 0x0000555555c946d1 in cpu_exec_setjmp (cpu=cpu@entry=0x5555578e0cb0, > > sc=sc@entry=0x7ffff4efd7b0) at ../../accel/tcg/cpu-exec.c:1029 > > #27 0x0000555555c94ebc in cpu_exec (cpu=cpu@entry=0x5555578e0cb0) at > > ../../accel/tcg/cpu-exec.c:1055 > > #28 0x0000555555cb8f53 in tcg_cpu_exec (cpu=cpu@entry=0x5555578e0cb0) at > > ../../accel/tcg/tcg-accel-ops.c:76 > > #29 0x0000555555cb90b0 in mttcg_cpu_thread_fn > > (arg=arg@entry=0x5555578e0cb0) at ../../accel/tcg/tcg-accel-ops-mttcg.c:95 > > #30 0x0000555555e57180 in qemu_thread_start (args=0x555557956000) at > > ../../util/qemu-thread-posix.c:541 > > #31 0x00007ffff78176ba in start_thread (arg=<optimized out>) at > > ./nptl/pthread_create.c:444 > > #32 0x00007ffff78a60d0 in clone3 () at > > ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 >
