KVM: Rework VCPU state writeback API
commitea375f9ab8c76686dca0af8cb4f87a4eb569cad3
authorJan Kiszka <jan.kiszka@siemens.com>
Mon, 1 Mar 2010 18:10:30 +0000 (1 19:10 +0100)
committerMarcelo Tosatti <mtosatti@redhat.com>
Thu, 4 Mar 2010 03:29:28 +0000 (4 00:29 -0300)
tree51e0476453c95a64bd34bc148082ac277a458203
parentb0b1d69079fcb9453f45aade9e9f6b71422147b0
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 <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
15 files changed:
exec.c
hw/apic.c
hw/ppc_newworld.c
hw/ppc_oldworld.c
hw/s390-virtio.c
kvm-all.c
kvm.h
savevm.c
sysemu.h
target-i386/kvm.c
target-i386/machine.c
target-ppc/kvm.c
target-ppc/machine.c
target-s390x/kvm.c
vl.c