Hi Salil,
On 12/3/24 02:59, Salil Mehta wrote:
KVM vCPU creation is done once during the vCPU realization when Qemu vCPU thread
is spawned. This is common to all the architectures as of now.
Hot-unplug of vCPU results in destruction of the vCPU object in QOM but the
corresponding KVM vCPU object in the Host KVM is not destroyed as KVM doesn't
support vCPU removal. Therefore, its representative KVM vCPU object/context in
Qemu is parked.
Refactor architecture common logic so that some APIs could be reused by vCPU
Hotplug code of some architectures likes ARM, Loongson etc. Update new/old APIs
with trace events instead of DPRINTF. No functional change is intended here.
Signed-off-by: Salil Mehta <salil.me...@huawei.com>
Reviewed-by: Gavin Shan <gs...@redhat.com>
Tested-by: Vishnu Pajjuri <vis...@os.amperecomputing.com>
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Tested-by: Xianglai Li <lixiang...@loongson.cn>
Tested-by: Miguel Luis <miguel.l...@oracle.com>
Reviewed-by: Shaoqin Huang <shahu...@redhat.com>
---
accel/kvm/kvm-all.c | 64 ++++++++++++++++++++++++++++++++----------
accel/kvm/trace-events | 5 +++-
include/sysemu/kvm.h | 16 +++++++++++
3 files changed, 69 insertions(+), 16 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index a8cecd040e..3bc3207bda 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -126,6 +126,7 @@ static QemuMutex kml_slots_lock;
#define kvm_slots_unlock() qemu_mutex_unlock(&kml_slots_lock)
static void kvm_slot_init_dirty_bitmap(KVMSlot *mem);
+static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id);
static inline void kvm_resample_fd_remove(int gsi)
{
@@ -314,14 +315,53 @@ err:
return ret;
}
+void kvm_park_vcpu(CPUState *cpu)
+{
+ struct KVMParkedVcpu *vcpu;
+
+ trace_kvm_park_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
+
+ 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);
+}
+
+int kvm_create_vcpu(CPUState *cpu)
+{
+ unsigned long vcpu_id = kvm_arch_vcpu_id(cpu);
+ KVMState *s = kvm_state;
+ int kvm_fd;
+
+ trace_kvm_create_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
+
+ /* check if the KVM vCPU already exist but is parked */
+ kvm_fd = kvm_get_vcpu(s, vcpu_id);
+ if (kvm_fd < 0) {
+ /* vCPU not parked: create a new KVM vCPU */
+ kvm_fd = kvm_vm_ioctl(s, KVM_CREATE_VCPU, vcpu_id);
+ if (kvm_fd < 0) {
+ error_report("KVM_CREATE_VCPU IOCTL failed for vCPU %lu", vcpu_id);
+ return kvm_fd;
+ }
+ }
+
+ cpu->kvm_fd = kvm_fd;
+ cpu->kvm_state = s;
+ cpu->vcpu_dirty = true;
+ cpu->dirty_pages = 0;
+ cpu->throttle_us_per_full = 0;
+
+ return 0;
+}
This seems generic enough to be implemented for all accelerators.
See AccelOpsClass in include/sysemu/accel-ops.h.
That said, can be done later on top.
