Re: [Qemu-devel] [PATCH] Enable async page faults

["Andreas Färber" <afaerber@suse.de>]

Am 09.07.2013 17:47, schrieb Dominik Dingel:
> S390 can also use async page faults, to enhance guest scheduling.
> But in the case of live migration we want to disable the feature and know
> if there are still notifications in flight.
> 
> Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
> ---
>  target-s390x/kvm.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index 42f758f..61df7d4 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -36,6 +36,7 @@
>  #include "sysemu/device_tree.h"
>  #include "qapi/qmp/qjson.h"
>  #include "monitor/monitor.h"
> +#include "migration/migration.h"
>  
>  /* #define DEBUG_KVM */
>  
> @@ -92,9 +93,50 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
>  
>  static int cap_sync_regs;
>  
> +static int apf_disable(QEMUFile *f, void *opaque)
> +{
> +    kvm_vm_ioctl(opaque, KVM_S390_APF_DISABLE);

Better don't pass opaques directly as a typed argument, especially in a
KVM file not widely tested; we just had such a runtime breakage.
KVMState *s = opaque; elegantly avoids it here and improves readability.

Regards,
Andreas

> +    return 0;
> +}
> +
> +static void apf_enable(void *opaque)
> +{
> +    kvm_vm_ioctl(opaque, KVM_S390_APF_ENABLE);
> +}
> +
> +static int apf_finish(QEMUFile *f, void *opaque, int version_id)
> +{
> +    apf_enable(opaque);
> +    return 0;
> +}
> +
> +static uint64_t apf_status(QEMUFile *f, void *opaque, uint64_t max_size)
> +{
> +    uint64_t rc = 0;
> +
> +    if (kvm_vm_ioctl(opaque, KVM_S390_APF_STATUS) !=
> +        KVM_S390_APF_DISABLED_NON_PENDING) {
> +        rc = 0xff0000;
> +    }
> +    return rc;
> +}
> +
> +SaveVMHandlers savevm_apf_handlers = {
> +    .save_live_setup = apf_disable,
> +    .save_live_iterate = NULL,
> +    .save_live_complete = NULL,
> +    .save_live_pending = apf_status,
> +    .load_state = apf_finish,
> +    .cancel = apf_enable,
> +};
> +
>  int kvm_arch_init(KVMState *s)
>  {
>      cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);
> +    if (kvm_check_extension(s, KVM_CAP_ASYNC_PF)) {
> +        register_savevm_live(NULL, "apf", -1, 1, &savevm_apf_handlers, s);
> +        kvm_vm_ioctl(s, KVM_S390_APF_ENABLE);
> +    }
>      return 0;
>  }
>  
> 


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