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cpu: Reclaim vCPU objects

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In order to deal well with the kvm vcpus (which can not be removed without any
protection), we do not close KVM vcpu fd, just record and mark it as stopped
into a list, so that we can reuse it for the appending cpu hot-add request if
possible. It is also the approach that kvm guys suggested:
https://www.mail-archive.com/kvm@vger.kernel.org/msg102839.html

Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
               [- Explicit CPU_REMOVE() from qemu_kvm/tcg_destroy_vcpu()
                  isn't needed as it is done from cpu_exec_exit()
                - Use iothread mutex instead of global mutex during
                  destroy
                - Don't cleanup vCPU object from vCPU thread context
                  but leave it to the callers (device_add/device_del)]
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Gu Zheng 2016-05-12 09:18:13 +05:30 • committed by David Gibson
parent 9dfeca7c6b
commit 4c055ab54f
5 changed files with 109 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

57
kvm-all.c
View file

@ -61,6 +61,12 @@
#define KVM_MSI_HASHTAB_SIZE 256
struct KVMParkedVcpu {
unsigned long vcpu_id;
int kvm_fd;
QLIST_ENTRY(KVMParkedVcpu) node;
};
struct KVMState
{
AccelState parent_obj;
@ -94,6 +100,7 @@ struct KVMState
QTAILQ_HEAD(msi_hashtab, KVMMSIRoute) msi_hashtab[KVM_MSI_HASHTAB_SIZE];
#endif
KVMMemoryListener memory_listener;
QLIST_HEAD(, KVMParkedVcpu) kvm_parked_vcpus;
};
KVMState *kvm_state;
@ -237,6 +244,53 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot)
return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);
}
int kvm_destroy_vcpu(CPUState *cpu)
{
KVMState *s = kvm_state;
long mmap_size;
struct KVMParkedVcpu *vcpu = NULL;
int ret = 0;
DPRINTF("kvm_destroy_vcpu\n");
mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
if (mmap_size < 0) {
ret = mmap_size;
DPRINTF("KVM_GET_VCPU_MMAP_SIZE failed\n");
goto err;
}
ret = munmap(cpu->kvm_run, mmap_size);
if (ret < 0) {
goto err;
}
vcpu = g_malloc0(sizeof(*vcpu));
vcpu->vcpu_id = kvm_arch_vcpu_id(cpu);
vcpu->kvm_fd = cpu->kvm_fd;
QLIST_INSERT_HEAD(&kvm_state->kvm_parked_vcpus, vcpu, node);
err:
return ret;
}
static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
{
struct KVMParkedVcpu *cpu;
QLIST_FOREACH(cpu, &s->kvm_parked_vcpus, node) {
if (cpu->vcpu_id == vcpu_id) {
int kvm_fd;
QLIST_REMOVE(cpu, node);
kvm_fd = cpu->kvm_fd;
g_free(cpu);
return kvm_fd;
}
}
return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
}
int kvm_init_vcpu(CPUState *cpu)
{
KVMState *s = kvm_state;
@ -245,7 +299,7 @@ int kvm_init_vcpu(CPUState *cpu)
DPRINTF("kvm_init_vcpu\n");
ret = kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)kvm_arch_vcpu_id(cpu));
ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
if (ret < 0) {
DPRINTF("kvm_create_vcpu failed\n");
goto err;
@ -1501,6 +1555,7 @@ static int kvm_init(MachineState *ms)
#ifdef KVM_CAP_SET_GUEST_DEBUG
QTAILQ_INIT(&s->kvm_sw_breakpoints);
#endif
QLIST_INIT(&s->kvm_parked_vcpus);
s->vmfd = -1;
s->fd = qemu_open("/dev/kvm", O_RDWR);
if (s->fd == -1) {