On Fri, 7 Jun 2024 12:56:42 +0100
Salil Mehta <salil.me...@huawei.com> 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. 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>
> Reviewed-by: Vishnu Pajjuri <vis...@os.amperecomputing.com>
> Reviewed-by: Nicholas Piggin <npig...@gmail.com>
> Tested-by: Zhao Liu <zhao1....@intel.com>
> Reviewed-by: Zhao Liu <zhao1....@intel.com>
> Reviewed-by: Harsh Prateek Bora <hars...@linux.ibm.com>
> ---
> accel/kvm/kvm-all.c | 95 ++++++++++++++++++++++++++++--------------
> accel/kvm/kvm-cpus.h | 1 -
> accel/kvm/trace-events | 5 ++-
> include/sysemu/kvm.h | 25 +++++++++++
> 4 files changed, 92 insertions(+), 34 deletions(-)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index c0be9f5eed..8f9128bb92 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -340,14 +340,71 @@ 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_unpark_vcpu(KVMState *s, unsigned long vcpu_id)
> +{
> + struct KVMParkedVcpu *cpu;
> + int kvm_fd = -ENOENT;
> +
> + QLIST_FOREACH(cpu, &s->kvm_parked_vcpus, node) {
> + if (cpu->vcpu_id == vcpu_id) {
> + QLIST_REMOVE(cpu, node);
> + kvm_fd = cpu->kvm_fd;
> + g_free(cpu);
> + }
> + }
> +
> + trace_kvm_unpark_vcpu(vcpu_id, kvm_fd > 0 ? "unparked" : "not found
> parked");
> +
> + return kvm_fd;
> +}
> +
> +int kvm_create_vcpu(CPUState *cpu)
> +{
> + unsigned long vcpu_id = kvm_arch_vcpu_id(cpu);
> + KVMState *s = kvm_state;
> + int kvm_fd;
> +
> + /* check if the KVM vCPU already exist but is parked */
> + kvm_fd = kvm_unpark_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;
> +
> + trace_kvm_create_vcpu(cpu->cpu_index, vcpu_id, kvm_fd);
> +
> + return 0;
> +}
Is there any reason why you are embedding/hiding kvm_state in new API
instead of passing it as argument (all callers have it defined, so why not
reuse that)?
otherwise patch lgtm
> +
> static int do_kvm_destroy_vcpu(CPUState *cpu)
> {
> KVMState *s = kvm_state;
> long mmap_size;
> - struct KVMParkedVcpu *vcpu = NULL;
> int ret = 0;
>
> - trace_kvm_destroy_vcpu();
> + trace_kvm_destroy_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
>
> ret = kvm_arch_destroy_vcpu(cpu);
> if (ret < 0) {
> @@ -373,10 +430,7 @@ 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;
> }
> @@ -389,24 +443,6 @@ void kvm_destroy_vcpu(CPUState *cpu)
> }
> }
>
> -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, Error **errp)
> {
> KVMState *s = kvm_state;
> @@ -415,19 +451,14 @@ 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/accel/kvm/kvm-cpus.h b/accel/kvm/kvm-cpus.h
> index ca40add32c..171b22fd29 100644
> --- a/accel/kvm/kvm-cpus.h
> +++ b/accel/kvm/kvm-cpus.h
> @@ -22,5 +22,4 @@ bool kvm_supports_guest_debug(void);
> int kvm_insert_breakpoint(CPUState *cpu, int type, vaddr addr, vaddr len);
> int kvm_remove_breakpoint(CPUState *cpu, int type, vaddr addr, vaddr len);
> void kvm_remove_all_breakpoints(CPUState *cpu);
> -
> #endif /* KVM_CPUS_H */
> diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events
> index 681ccb667d..37626c1ac5 100644
> --- a/accel/kvm/trace-events
> +++ b/accel/kvm/trace-events
> @@ -9,6 +9,10 @@ kvm_device_ioctl(int fd, int type, void *arg) "dev fd %d,
> type 0x%x, arg %p"
> kvm_failed_reg_get(uint64_t id, const char *msg) "Warning: Unable to
> retrieve ONEREG %" PRIu64 " from KVM: %s"
> kvm_failed_reg_set(uint64_t id, const char *msg) "Warning: Unable to set
> ONEREG %" PRIu64 " to KVM: %s"
> kvm_init_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu"
> +kvm_create_vcpu(int cpu_index, unsigned long arch_cpu_id, int kvm_fd)
> "index: %d, id: %lu, kvm fd: %d"
> +kvm_destroy_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id:
> %lu"
> +kvm_park_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu"
> +kvm_unpark_vcpu(unsigned long arch_cpu_id, const char *msg) "id: %lu %s"
> kvm_irqchip_commit_routes(void) ""
> kvm_irqchip_add_msi_route(char *name, int vector, int virq) "dev %s vector
> %d virq %d"
> kvm_irqchip_update_msi_route(int virq) "Updating MSI route virq=%d"
> @@ -25,7 +29,6 @@ kvm_dirty_ring_reaper(const char *s) "%s"
> kvm_dirty_ring_reap(uint64_t count, int64_t t) "reaped %"PRIu64" pages (took
> %"PRIi64" us)"
> kvm_dirty_ring_reaper_kick(const char *reason) "%s"
> kvm_dirty_ring_flush(int finished) "%d"
> -kvm_destroy_vcpu(void) ""
> kvm_failed_get_vcpu_mmap_size(void) ""
> kvm_cpu_exec(void) ""
> kvm_interrupt_exit_request(void) ""
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index c31d9c7356..c4a914b3d8 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -313,6 +313,31 @@ int kvm_create_device(KVMState *s, uint64_t type, bool
> test);
> */
> bool kvm_device_supported(int vmfd, uint64_t type);
>
> +/**
> + * kvm_create_vcpu - Gets a parked KVM vCPU or creates a KVM vCPU
> + * @cpu: QOM CPUState object for which KVM vCPU has to be fetched/created.
> + *
> + * @returns: 0 when success, errno (<0) when failed.
> + */
> +int kvm_create_vcpu(CPUState *cpu);
> +
> +/**
> + * kvm_park_vcpu - Park QEMU KVM vCPU context
> + * @cpu: QOM CPUState object for which QEMU KVM vCPU context has to be
> parked.
> + *
> + * @returns: none
> + */
> +void kvm_park_vcpu(CPUState *cpu);
> +
> +/**
> + * kvm_unpark_vcpu - unpark QEMU KVM vCPU context
> + * @s: KVM State
> + * @vcpu_id: Architecture vCPU ID of the parked vCPU
> + *
> + * @returns: KVM fd
> + */
> +int kvm_unpark_vcpu(KVMState *s, unsigned long vcpu_id);
> +
> /* Arch specific hooks */
>
> extern const KVMCapabilityInfo kvm_arch_required_capabilities[];
