From: Harsh Prateek Bora <harshpb@linux.ibm.com>
To: Salil Mehta <salil.mehta@huawei.com>,
qemu-devel@nongnu.org, qemu-arm@nongnu.org
Cc: maz@kernel.org, jean-philippe@linaro.org,
jonathan.cameron@huawei.com, lpieralisi@kernel.org,
peter.maydell@linaro.org, richard.henderson@linaro.org,
imammedo@redhat.com, andrew.jones@linux.dev, david@redhat.com,
philmd@linaro.org, eric.auger@redhat.com, oliver.upton@linux.dev,
pbonzini@redhat.com, mst@redhat.com, will@kernel.org,
gshan@redhat.com, rafael@kernel.org, alex.bennee@linaro.org,
linux@armlinux.org.uk, darren@os.amperecomputing.com,
ilkka@os.amperecomputing.com, vishnu@os.amperecomputing.com,
karl.heubaum@oracle.com, miguel.luis@oracle.com,
salil.mehta@opnsrc.net, zhukeqian1@huawei.com,
wangxiongfeng2@huawei.com, wangyanan55@huawei.com,
jiakernel2@gmail.com, maobibo@loongson.cn,
lixianglai@loongson.cn, linuxarm@huawei.com,
Vaibhav Jain <vaibhav@linux.ibm.com>,
sbhat@linux.ibm.com
Subject: Re: [PATCH V8 1/8] accel/kvm: Extract common KVM vCPU {creation, parking} code
Date: Fri, 22 Mar 2024 13:45:10 +0530 [thread overview]
Message-ID: <ca178aae-82b9-4150-9965-50d968787d23@linux.ibm.com> (raw)
In-Reply-To: <20240312020000.12992-2-salil.mehta@huawei.com>
+ Vaibhav, Shiva
Hi Salil,
I came across your patch while trying to solve a related problem on
spapr. One query below ..
On 3/12/24 07:29, Salil Mehta via 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.mehta@huawei.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Tested-by: Xianglai Li <lixianglai@loongson.cn>
> Tested-by: Miguel Luis <miguel.luis@oracle.com>
> Reviewed-by: Shaoqin Huang <shahuang@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;
> +}
> +
> 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) {
> @@ -347,10 +387,7 @@ 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;
> }
> @@ -371,6 +408,8 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
> if (cpu->vcpu_id == vcpu_id) {
> int kvm_fd;
>
> + trace_kvm_get_vcpu(vcpu_id);
> +
> QLIST_REMOVE(cpu, node);
> kvm_fd = cpu->kvm_fd;
> g_free(cpu);
> @@ -378,7 +417,7 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
> }
> }
>
> - return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
> + return -ENOENT;
> }
>
> int kvm_init_vcpu(CPUState *cpu, Error **errp)
> @@ -389,19 +428,14 @@ 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));
If a vcpu hotplug fails due to failure with kvm_create_vcpu ioctl,
current behaviour would be to bring down the guest as errp is
&error_fatal. Any thoughts on how do we ensure that a failure with
kvm_create_vcpu ioctl for hotplugged cpus (only) doesnt bring down the
guest and fail gracefully (by reporting error to user on monitor?)?
regards,
Harsh
> 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/trace-events b/accel/kvm/trace-events
> index a25902597b..5558cff0dc 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) "index: %d id: %lu"
> +kvm_get_vcpu(unsigned long arch_cpu_id) "id: %lu"
> +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_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 fad9a7e8ff..2ed928aa71 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -435,6 +435,22 @@ 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);
>
> +/**
> + * 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);
> +
> #endif /* NEED_CPU_H */
>
> void kvm_cpu_synchronize_state(CPUState *cpu);
next prev parent reply other threads:[~2024-03-22 8:17 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-12 1:59 [PATCH V8 0/8] Add architecture agnostic code to support vCPU Hotplug Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 1/8] accel/kvm: Extract common KVM vCPU {creation, parking} code Salil Mehta via
2024-03-22 8:15 ` Harsh Prateek Bora [this message]
2024-04-23 6:44 ` Harsh Prateek Bora
2024-05-03 18:56 ` Salil Mehta via
2024-05-03 18:43 ` Salil Mehta via
2024-04-04 13:59 ` [PATCH V8 1/8] accel/kvm: Extract common KVM vCPU {creation,parking} code Vishnu Pajjuri
2024-05-03 16:23 ` Salil Mehta via
2024-05-07 12:39 ` Vishnu Pajjuri
2024-05-07 12:51 ` Salil Mehta
2024-05-03 9:40 ` Philippe Mathieu-Daudé
2024-05-03 15:57 ` Salil Mehta via
2024-05-03 18:22 ` Philippe Mathieu-Daudé
2024-05-08 10:46 ` Salil Mehta via
2024-05-10 14:43 ` Philippe Mathieu-Daudé
2024-03-12 1:59 ` [PATCH V8 2/8] hw/acpi: Move CPU ctrl-dev MMIO region len macro to common header file Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 3/8] hw/acpi: Update ACPI GED framework to support vCPU Hotplug Salil Mehta via
2024-03-13 6:14 ` Zhao Liu
2024-05-03 19:59 ` Salil Mehta via
2024-05-06 9:05 ` Zhao Liu
2024-05-06 9:27 ` Salil Mehta via
2024-04-04 14:01 ` Vishnu Pajjuri
2024-05-03 20:09 ` Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 4/8] hw/acpi: Update GED _EVT method AML with CPU scan Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 5/8] hw/acpi: Update CPUs AML with cpu-(ctrl)dev change Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 6/8] physmem: Add helper function to destroy CPU AddressSpace Salil Mehta via
2024-03-15 1:16 ` 答复: " zhukeqian via
2024-05-04 1:40 ` Salil Mehta
2024-05-04 13:40 ` Peter Maydell
2024-05-06 9:06 ` Salil Mehta via
2024-05-06 9:28 ` Peter Maydell
2024-05-07 0:11 ` Salil Mehta via
2024-05-07 9:02 ` Peter Maydell
2024-05-07 9:56 ` Salil Mehta via
2024-03-12 1:59 ` [PATCH V8 7/8] gdbstub: Add helper function to unregister GDB register space Salil Mehta via
2024-04-04 14:02 ` Vishnu Pajjuri
2024-05-03 19:36 ` Salil Mehta via
2024-03-12 2:00 ` [PATCH V8 8/8] docs/specs/acpi_hw_reduced_hotplug: Add the CPU Hotplug Event Bit Salil Mehta via
2024-03-12 18:00 ` [PATCH V8 0/8] Add architecture agnostic code to support vCPU Hotplug Michael S. Tsirkin
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