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KVM: Rework VCPU state writeback API

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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 <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka
2010-03-01 19:10:30 +01:00
committed by Marcelo Tosatti
parent b0b1d69079
commit ea375f9ab8
15 changed files with 77 additions and 52 deletions
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19
kvm-all.c
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@@ -156,10 +156,6 @@ static void kvm_reset_vcpu(void *opaque)
CPUState *env = opaque;
kvm_arch_reset_vcpu(env);
if (kvm_arch_put_registers(env)) {
fprintf(stderr, "Fatal: kvm vcpu reset failed\n");
abort();
}
}
int kvm_irqchip_in_kernel(void)
@@ -214,7 +210,6 @@ int kvm_init_vcpu(CPUState *env)
if (ret == 0) {
qemu_register_reset(kvm_reset_vcpu, env);
kvm_arch_reset_vcpu(env);
ret = kvm_arch_put_registers(env);
}
err:
return ret;
@@ -753,6 +748,18 @@ void kvm_cpu_synchronize_state(CPUState *env)
}
}
void kvm_cpu_synchronize_post_reset(CPUState *env)
{
kvm_arch_put_registers(env, KVM_PUT_RESET_STATE);
env->kvm_vcpu_dirty = 0;
}
void kvm_cpu_synchronize_post_init(CPUState *env)
{
kvm_arch_put_registers(env, KVM_PUT_FULL_STATE);
env->kvm_vcpu_dirty = 0;
}
int kvm_cpu_exec(CPUState *env)
{
struct kvm_run *run = env->kvm_run;
@@ -770,7 +777,7 @@ int kvm_cpu_exec(CPUState *env)
#endif
if (env->kvm_vcpu_dirty) {
kvm_arch_put_registers(env);
kvm_arch_put_registers(env, KVM_PUT_RUNTIME_STATE);
env->kvm_vcpu_dirty = 0;
}