From ea375f9ab8c76686dca0af8cb4f87a4eb569cad3 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Mon, 1 Mar 2010 19:10:30 +0100 Subject: KVM: Rework VCPU state writeback API This grand cleanup drops all reset and vmsave/load related synchronization points in favor of four(!) generic hooks: - cpu_synchronize_all_states in qemu_savevm_state_complete (initial sync from kernel before vmsave) - cpu_synchronize_all_post_init in qemu_loadvm_state (writeback after vmload) - cpu_synchronize_all_post_init in main after machine init - cpu_synchronize_all_post_reset in qemu_system_reset (writeback after system reset) These writeback points + the existing one of VCPU exec after cpu_synchronize_state map on three levels of writeback: - KVM_PUT_RUNTIME_STATE (during runtime, other VCPUs continue to run) - KVM_PUT_RESET_STATE (on synchronous system reset, all VCPUs stopped) - KVM_PUT_FULL_STATE (on init or vmload, all VCPUs stopped as well) This level is passed to the arch-specific VCPU state writing function that will decide which concrete substates need to be written. That way, no writer of load, save or reset functions that interact with in-kernel KVM states will ever have to worry about synchronization again. That also means that a lot of reasons for races, segfaults and deadlocks are eliminated. cpu_synchronize_state remains untouched, just as Anthony suggested. We continue to need it before reading or writing of VCPU states that are also tracked by in-kernel KVM subsystems. Consequently, this patch removes many cpu_synchronize_state calls that are now redundant, just like remaining explicit register syncs. Signed-off-by: Jan Kiszka Signed-off-by: Marcelo Tosatti --- savevm.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'savevm.c') diff --git a/savevm.c b/savevm.c index 4b58663960..a6e774b4d0 100644 --- a/savevm.c +++ b/savevm.c @@ -1345,6 +1345,8 @@ int qemu_savevm_state_complete(Monitor *mon, QEMUFile *f) { SaveStateEntry *se; + cpu_synchronize_all_states(); + QTAILQ_FOREACH(se, &savevm_handlers, entry) { if (se->save_live_state == NULL) continue; @@ -1545,6 +1547,8 @@ int qemu_loadvm_state(QEMUFile *f) } } + cpu_synchronize_all_post_init(); + ret = 0; out: -- cgit v1.2.3