RE: [PATCH V4 01/10] accel/kvm: Extract common KVM vCPU {creation,parking} code

[Salil Mehta]

Hi Gavin,

> From: Gavin Shan <gshan@redhat.com>
> Sent: Wednesday, October 11, 2023 8:09 AM
> 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
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> Subject: Re: [PATCH V4 01/10] accel/kvm: Extract common KVM vCPU
> {creation,parking} code
> 
> Hi Salil,
> 
> On 10/10/23 06:35, Salil Mehta wrote:
> > KVM vCPU creation is done once during the initialization of the VM when Qemu
> > thread is spawned. This is common to all the architectures.
> >
> > 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 and its
> > representative KVM vCPU object/context in Qemu is parked.
> >
> > Refactor common logic so that some APIs could be reused by vCPU Hotplug 
> > code.
> >
> > Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> > ---
> >   accel/kvm/kvm-all.c    | 64 ++++++++++++++++++++++++++++++++----------
> >   accel/kvm/trace-events |  4 +++
> >   include/sysemu/kvm.h   | 16 +++++++++++
> >   3 files changed, 69 insertions(+), 15 deletions(-)
> >
> 
> With the following one comment addressed:
> 
> Reviewed-by: Gavin Shan <gshan@redhat.com>


Thanks


[...]

> > diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events
> > index 399aaeb0ec..08e2dc253f 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) "creating KVM 
> > cpu: cpu_index: %d arch vcpu-id: %lu"
> > +kvm_get_vcpu(unsigned long arch_cpu_id) "unparking KVM vcpu: arch vcpu-id: 
> > %lu"
> > +kvm_destroy_vcpu(int cpu_index, unsigned long arch_cpu_id) "destroy vcpu: 
> > cpu_index: %d arch vcpu-id: %lu"
> > +kvm_park_vcpu(int cpu_index, unsigned long arch_cpu_id) "parking KVM vcpu: 
> > cpu_index: %d arch vcpu-id: %lu"
> 
> I don't think we need the duplicate identifiers like "creating KVM cpu"
> since the event name can serve the purpose. Besides, the parameters
> are descriptive by "index: %d id: %lu", used by kvm_init_vcpu(). We just
> need to follow that pattern. Otherwise, inconsistent output will be printed
> by kvm_init_vcpu() and kvm_get_vcpu(). So I would change them like below:
> 
> 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"

No problem. Will fix

Only executed below to check for new trace counters:
Qemu> info trace-events


Thanks
Salil.