On 5/7/2024 5:12 PM, Peter Zijlstra wrote:
On Mon, May 06, 2024 at 05:29:34AM +0000, Mingwei Zhang wrote:+void kvm_set_guest_pmi_handler(void (*handler)(void)) +{ + if (handler) { + kvm_guest_pmi_handler = handler; + } else { + kvm_guest_pmi_handler = dummy_handler; + synchronize_rcu(); + } +} +EXPORT_SYMBOL_GPL(kvm_set_guest_pmi_handler);Just for my edification, after synchronize_rcu() nobody should observe the old handler, but what guarantees there's not still one running?
Interrupts handler can be regarded as RCU read-side critical section, once synchronize_rcu returns, no one accessing the old handler lefts.
I'm thinking the fact that these handlers run with IRQs disabled, and synchronize_rcu() also very much ensures all prior non-preempt sections are complete?
Yes :) Thanks, Yanfei
