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qemu/accel/tcg
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Jonathan Cameron 6aba908d2b tcg: Avoid double lock if page tables happen to be in mmio memory. 
On i386, after fixing the page walking code to work with pages in
MMIO memory (specifically CXL emulated interleaved memory),
a crash was seen in an interrupt handling path.

Useful part of backtrace

7  0x0000555555ab1929 in bql_lock_impl (file=0x555556049122 "../../accel/tcg/cputlb.c", line=2033) at ../../system/cpus.c:524
8  bql_lock_impl (file=file@entry=0x555556049122 "../../accel/tcg/cputlb.c", line=line@entry=2033) at ../../system/cpus.c:520
9  0x0000555555c9f7d6 in do_ld_mmio_beN (cpu=0x5555578e0cb0, full=0x7ffe88012950, ret_be=ret_be@entry=0, addr=19595792376, size=size@entry=8, mmu_idx=4, type=MMU_DATA_LOAD, ra=0) at ../../accel/tcg/cputlb.c:2033
10 0x0000555555ca0fbd in do_ld_8 (cpu=cpu@entry=0x5555578e0cb0, p=p@entry=0x7ffff4efd1d0, mmu_idx=<optimized out>, type=type@entry=MMU_DATA_LOAD, memop=<optimized out>, ra=ra@entry=0) at ../../accel/tcg/cputlb.c:2356
11 0x0000555555ca341f in do_ld8_mmu (cpu=cpu@entry=0x5555578e0cb0, addr=addr@entry=19595792376, oi=oi@entry=52, ra=0, ra@entry=52, access_type=access_type@entry=MMU_DATA_LOAD) at ../../accel/tcg/cputlb.c:2439
12 0x0000555555ca5f59 in cpu_ldq_mmu (ra=52, oi=52, addr=19595792376, env=0x5555578e3470) at ../../accel/tcg/ldst_common.c.inc:169
13 cpu_ldq_le_mmuidx_ra (env=0x5555578e3470, addr=19595792376, mmu_idx=<optimized out>, ra=ra@entry=0) at ../../accel/tcg/ldst_common.c.inc:301
14 0x0000555555b4b5fc in ptw_ldq (ra=0, in=0x7ffff4efd320) at ../../target/i386/tcg/sysemu/excp_helper.c:98
15 ptw_ldq (ra=0, in=0x7ffff4efd320) at ../../target/i386/tcg/sysemu/excp_helper.c:93
16 mmu_translate (env=env@entry=0x5555578e3470, in=0x7ffff4efd3e0, out=0x7ffff4efd3b0, err=err@entry=0x7ffff4efd3c0, ra=ra@entry=0) at ../../target/i386/tcg/sysemu/excp_helper.c:174
17 0x0000555555b4c4b3 in get_physical_address (ra=0, err=0x7ffff4efd3c0, out=0x7ffff4efd3b0, mmu_idx=0, access_type=MMU_DATA_LOAD, addr=18446741874686299840, env=0x5555578e3470) at ../../target/i386/tcg/sysemu/excp_helper.c:580
18 x86_cpu_tlb_fill (cs=0x5555578e0cb0, addr=18446741874686299840, size=<optimized out>, access_type=MMU_DATA_LOAD, mmu_idx=0, probe=<optimized out>, retaddr=0) at ../../target/i386/tcg/sysemu/excp_helper.c:606
19 0x0000555555ca0ee9 in tlb_fill (retaddr=0, mmu_idx=0, access_type=MMU_DATA_LOAD, size=<optimized out>, addr=18446741874686299840, cpu=0x7ffff4efd540) at ../../accel/tcg/cputlb.c:1315
20 mmu_lookup1 (cpu=cpu@entry=0x5555578e0cb0, data=data@entry=0x7ffff4efd540, mmu_idx=0, access_type=access_type@entry=MMU_DATA_LOAD, ra=ra@entry=0) at ../../accel/tcg/cputlb.c:1713
21 0x0000555555ca2c61 in mmu_lookup (cpu=cpu@entry=0x5555578e0cb0, addr=addr@entry=18446741874686299840, oi=oi@entry=32, ra=ra@entry=0, type=type@entry=MMU_DATA_LOAD, l=l@entry=0x7ffff4efd540) at ../../accel/tcg/cputlb.c:1803
22 0x0000555555ca3165 in do_ld4_mmu (cpu=cpu@entry=0x5555578e0cb0, addr=addr@entry=18446741874686299840, oi=oi@entry=32, ra=ra@entry=0, access_type=access_type@entry=MMU_DATA_LOAD) at ../../accel/tcg/cputlb.c:2416
23 0x0000555555ca5ef9 in cpu_ldl_mmu (ra=0, oi=32, addr=18446741874686299840, env=0x5555578e3470) at ../../accel/tcg/ldst_common.c.inc:158
24 cpu_ldl_le_mmuidx_ra (env=env@entry=0x5555578e3470, addr=addr@entry=18446741874686299840, mmu_idx=<optimized out>, ra=ra@entry=0) at ../../accel/tcg/ldst_common.c.inc:294
25 0x0000555555bb6cdd in do_interrupt64 (is_hw=1, next_eip=18446744072399775809, error_code=0, is_int=0, intno=236, env=0x5555578e3470) at ../../target/i386/tcg/seg_helper.c:889
26 do_interrupt_all (cpu=cpu@entry=0x5555578e0cb0, intno=236, is_int=is_int@entry=0, error_code=error_code@entry=0, next_eip=next_eip@entry=0, is_hw=is_hw@entry=1) at ../../target/i386/tcg/seg_helper.c:1130
27 0x0000555555bb87da in do_interrupt_x86_hardirq (env=env@entry=0x5555578e3470, intno=<optimized out>, is_hw=is_hw@entry=1) at ../../target/i386/tcg/seg_helper.c:1162
28 0x0000555555b5039c in x86_cpu_exec_interrupt (cs=0x5555578e0cb0, interrupt_request=<optimized out>) at ../../target/i386/tcg/sysemu/seg_helper.c:197
29 0x0000555555c94480 in cpu_handle_interrupt (last_tb=<synthetic pointer>, cpu=0x5555578e0cb0) at ../../accel/tcg/cpu-exec.c:844

Peter identified this as being due to the BQL already being
held when the page table walker encounters MMIO memory and attempts
to take the lock again.  There are other examples of similar paths
TCG, so this follows the approach taken in those of simply checking
if the lock is already held and if it is, don't take it again.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20240219173153.12114-4-Jonathan.Cameron@huawei.com>
[rth: Use BQL_LOCK_GUARD]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2024-02-29 11:35:36 -10:00
..
atomic_common.c.inc tcg: Use HAVE_CMPXCHG128 instead of CONFIG_CMPXCHG128 2023-07-15 08:02:49 +01:00
atomic_template.h accel/tcg: Modify atomic_mmu_lookup() to use CPUState 2023-10-04 11:03:54 -07:00
cpu-exec-common.c accel/tcg: Make cpu-exec-common.c a target agnostic unit 2023-10-04 11:03:54 -07:00
cpu-exec.c accel/tcg: Set can_do_io at at start of lookup_tb_ptr helper 2024-02-29 11:35:36 -10:00
cputlb.c tcg: Avoid double lock if page tables happen to be in mmio memory. 2024-02-29 11:35:36 -10:00
icount-common.c util/async: Only call icount_notify_exit() if icount is enabled 2024-01-19 12:28:59 +01:00
internal-common.h accel/tcg: Move HMP info jit and info opcount code 2023-11-06 08:27:21 -08:00
internal-target.h accel/tcg: Make cpu-exec-common.c a target agnostic unit 2023-10-04 11:03:54 -07:00
ldst_atomicity.c.inc accel/tcg: correct typos 2024-02-20 22:21:18 +03:00
ldst_common.c.inc include/exec: Change cpu_mmu_index argument to CPUState 2024-02-03 16:46:10 +10:00
meson.build accel/tcg: Rename tcg_ss[] -> tcg_specific_ss[] in meson 2024-01-29 21:04:10 +10:00
monitor.c accel/tcg: Move HMP info jit and info opcount code 2023-11-06 08:27:21 -08:00
plugin-gen.c plugins: create CPUPluginState and migrate plugin_mask 2024-02-28 09:11:42 +00:00
plugin-helpers.h plugins: Use different helpers when reading registers 2024-02-28 09:11:42 +00:00
tb-context.h tcg: Move tb_phys_invalidate_count to tb_ctx 2021-07-09 09:38:33 -07:00
tb-hash.h accel/tcg: Widen pc to vaddr in CPUJumpCache 2023-06-26 17:32:59 +02:00
tb-jmp-cache.h cpu-exec: simplify jump cache management 2024-01-29 07:06:03 +10:00
tb-maint.c accel/tcg: Remove tb_invalidate_phys_page() from system emulation 2024-01-19 12:28:59 +01:00
tcg-accel-ops-icount.c Replace "iothread lock" with "BQL" in comments 2024-01-08 10:45:43 -05:00
tcg-accel-ops-icount.h accel/tcg/tcg-accel-ops-rr: ensure fairness with icount 2023-05-11 09:53:41 +01:00
tcg-accel-ops-mttcg.c accel/tcg: Rename tcg_cpus_exec() -> tcg_cpu_exec() 2024-01-29 21:04:10 +10:00
tcg-accel-ops-mttcg.h Clean up header guards that don't match their file name 2022-05-11 16:49:06 +02:00
tcg-accel-ops-rr.c accel/tcg: Rename tcg_cpus_exec() -> tcg_cpu_exec() 2024-01-29 21:04:10 +10:00
tcg-accel-ops-rr.h Clean up header guards that don't match their file name 2022-05-11 16:49:06 +02:00
tcg-accel-ops.c accel/tcg: Rename tcg_cpus_exec() -> tcg_cpu_exec() 2024-01-29 21:04:10 +10:00
tcg-accel-ops.h accel/tcg: Rename tcg_cpus_exec() -> tcg_cpu_exec() 2024-01-29 21:04:10 +10:00
tcg-all.c tcg: Split out tcg init functions to tcg/startup.h 2023-10-04 11:03:54 -07:00
tcg-runtime-gvec.c tcg: Add gvec compare with immediate and scalar operand 2023-09-16 14:57:15 +00:00
tcg-runtime.c tcg: Split helper-proto.h 2023-06-05 12:04:29 -07:00
tcg-runtime.h tcg: Add gvec compare with immediate and scalar operand 2023-09-16 14:57:15 +00:00
trace-events accel/tcg: Remove trace events from trace-root.h 2022-12-20 17:11:12 -08:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
translate-all.c accel/tcg: Move perf and debuginfo support to tcg/ 2024-01-29 21:04:10 +10:00
translator.c accel/tcg: Remove CF_LAST_IO 2023-11-14 10:40:54 -08:00
user-exec-stub.c accel: Introduce cpu_exec_reset_hold() 2023-11-07 12:13:27 +01:00
user-exec.c tcg: Correct invalid mentions of 'softmmu' by 'system-mode' 2023-10-07 19:02:33 +02:00
watchpoint.c system/watchpoint: Move TCG specific code to accel/tcg/ 2024-01-19 12:28:59 +01:00