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[PATCH RFC V2 05/37] accel/kvm: Extract common KVM vCPU {creation, parki
From: |
Salil Mehta |
Subject: |
[PATCH RFC V2 05/37] accel/kvm: Extract common KVM vCPU {creation, parking} code |
Date: |
Tue, 26 Sep 2023 11:04:04 +0100 |
KVM vCPU creation is done once during the initialization of the VM when Qemu
threads are spawned. This is common to all the architectures. If the
architecture
supports vCPU hot-{un}plug then this KVM vCPU creation could be deferred to
later point as well. Some architectures might in any case create KVM vCPUs for
the yet-to-be plugged vCPUs (i.e. QoM Object & thread does not exists) during VM
init time and park them.
Hot-unplug of vCPU results in destruction of the vCPU objects in QOM but
the KVM vCPU objects in the Host KVM are not destroyed and their representative
KVM vCPU objects in Qemu are parked.
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
accel/kvm/kvm-all.c | 61 ++++++++++++++++++++++++++++++++++----------
include/sysemu/kvm.h | 2 ++
2 files changed, 49 insertions(+), 14 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 7b3da8dc3a..86e9c9ea60 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -137,6 +137,7 @@ 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)
{
@@ -320,11 +321,51 @@ err:
return ret;
}
+void kvm_park_vcpu(CPUState *cpu)
+{
+ unsigned long vcpu_id = cpu->cpu_index;
+ struct KVMParkedVcpu *vcpu;
+
+ vcpu = g_malloc0(sizeof(*vcpu));
+ vcpu->vcpu_id = vcpu_id;
+ 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 = cpu->cpu_index;
+ KVMState *s = kvm_state;
+ int ret;
+
+ DPRINTF("kvm_create_vcpu\n");
+
+ /* check if the KVM vCPU already exist but is parked */
+ ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
+ if (ret > 0) {
+ goto found;
+ }
+
+ /* create a new KVM vcpu */
+ ret = kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
+ if (ret < 0) {
+ return ret;
+ }
+
+found:
+ cpu->vcpu_dirty = true;
+ cpu->kvm_fd = ret;
+ cpu->kvm_state = s;
+ cpu->dirty_pages = 0;
+ cpu->throttle_us_per_full = 0;
+
+ return 0;
+}
+
static int do_kvm_destroy_vcpu(CPUState *cpu)
{
KVMState *s = kvm_state;
long mmap_size;
- struct KVMParkedVcpu *vcpu = NULL;
int ret = 0;
DPRINTF("kvm_destroy_vcpu\n");
@@ -353,10 +394,7 @@ static int do_kvm_destroy_vcpu(CPUState *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);
+ kvm_park_vcpu(cpu);
err:
return ret;
}
@@ -384,7 +422,7 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
}
}
- return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
+ return -1;
}
int kvm_init_vcpu(CPUState *cpu, Error **errp)
@@ -395,19 +433,14 @@ int kvm_init_vcpu(CPUState *cpu, Error **errp)
trace_kvm_init_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
- ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
+ ret = kvm_create_vcpu(cpu);
if (ret < 0) {
- error_setg_errno(errp, -ret, "kvm_init_vcpu: kvm_get_vcpu failed
(%lu)",
+ error_setg_errno(errp, -ret,
+ "kvm_init_vcpu: kvm_create_vcpu failed (%lu)",
kvm_arch_vcpu_id(cpu));
goto err;
}
- cpu->kvm_fd = ret;
- cpu->kvm_state = s;
- cpu->vcpu_dirty = true;
- cpu->dirty_pages = 0;
- cpu->throttle_us_per_full = 0;
-
mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
if (mmap_size < 0) {
ret = mmap_size;
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 115f0cca79..2c34889b01 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -473,6 +473,8 @@ void kvm_set_sigmask_len(KVMState *s, unsigned int
sigmask_len);
int kvm_physical_memory_addr_from_host(KVMState *s, void *ram_addr,
hwaddr *phys_addr);
+int kvm_create_vcpu(CPUState *cpu);
+void kvm_park_vcpu(CPUState *cpu);
#endif /* NEED_CPU_H */
--
2.34.1
- [PATCH RFC V2 00/37] Support of Virtual CPU Hotplug for ARMv8 Arch, (continued)
- [PATCH RFC V2 00/37] Support of Virtual CPU Hotplug for ARMv8 Arch, Salil Mehta, 2023/09/26
- [PATCH RFC V2 01/37] arm/virt, target/arm: Add new ARMCPU {socket, cluster, core, thread}-id property, Salil Mehta, 2023/09/26
- [PATCH RFC V2 02/37] cpus-common: Add common CPU utility for possible vCPUs, Salil Mehta, 2023/09/26
- [PATCH RFC V2 03/37] hw/arm/virt: Move setting of common CPU properties in a function, Salil Mehta, 2023/09/26
- [PATCH RFC V2 04/37] arm/virt, target/arm: Machine init time change common to vCPU {cold|hot}-plug, Salil Mehta, 2023/09/26
- [PATCH RFC V2 05/37] accel/kvm: Extract common KVM vCPU {creation, parking} code,
Salil Mehta <=
- [PATCH RFC V2 06/37] arm/virt, kvm: Pre-create disabled possible vCPUs @machine init, Salil Mehta, 2023/09/26
- [PATCH RFC V2 07/37] arm/virt, gicv3: Changes to pre-size GIC with possible vcpus @machine init, Salil Mehta, 2023/09/26
- [PATCH RFC V2 08/37] arm/virt: Init PMU at host for all possible vcpus, Salil Mehta, 2023/09/26
- [PATCH RFC V2 09/37] hw/acpi: Move CPU ctrl-dev MMIO region len macro to common header file, Salil Mehta, 2023/09/26
- [PATCH RFC V2 10/37] arm/acpi: Enable ACPI support for vcpu hotplug, Salil Mehta, 2023/09/26