The current 'timecmp' field in vmstate_riscv_mtimer is insufficient to keep
timers functional after migration.
If an mtimer's entry in 'mtimer->timers' is active at the time the snapshot
is taken, it means riscv_aclint_mtimer_write_timecmp() has written to
'mtimecmp' and scheduled a timer into QEMU's main loop 'timer_list'.
During snapshot save, these active timers must also be migrated; otherwise,
after snapshot load there is no mechanism to restore 'mtimer->timers' back
into the 'timer_list', and any pending timer events would be lost.
QEMU's migration framework commonly uses VMSTATE_TIMER_xxx macros to save
and restore 'QEMUTimer' variables. However, 'timers' is a pointer array
with variable length, and vmstate.h did not previously provide a helper
macro for such type.
This commit adds a new macro, 'VMSTATE_TIMER_PTR_VARRAY', to handle saving
and restoring a variable-length array of 'QEMUTimer *'. We then use this
macro to migrate the 'mtimer->timers' array, ensuring that timer events
remain scheduled correctly after snapshot load.
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Signed-off-by: TANG Tiancheng <lyndra@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250911-timers-v3-3-60508f640050@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
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