mirror of https://github.com/proxmox/mirror_qemu
36c651c226
A TCG vCPU doing a busy loop systematicaly hangs the QEMU monitor if the user passes 'device_add' without argument. This is because drain_cpu_all() which is called from qmp_device_add() cannot return if readers don't exit read-side critical sections. That is typically what busy-looping TCG vCPUs do: int cpu_exec(CPUState *cpu) { [...] rcu_read_lock(); [...] while (!cpu_handle_exception(cpu, &ret)) { // Busy loop keeps vCPU here } [...] rcu_read_unlock(); return ret; } For MTTCG, have all vCPU threads register a force_rcu notifier that will kick them out of the loop using async_run_on_cpu(). The notifier is called with the rcu_registry_lock mutex held, using async_run_on_cpu() ensures there are no deadlocks. For RR, a single thread runs all vCPUs. Just register a single notifier that kicks the current vCPU to the next one. For MTTCG: Suggested-by: Paolo Bonzini <pbonzini@redhat.com> For RR: Suggested-by: Richard Henderson <richard.henderson@linaro.org> Fixes: |
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hvf | ||
kvm | ||
qtest | ||
stubs | ||
tcg | ||
xen | ||
Kconfig | ||
accel-common.c | ||
accel-softmmu.c | ||
accel-softmmu.h | ||
accel-user.c | ||
dummy-cpus.c | ||
meson.build |