> From: Harsh Prateek Bora <hars...@linux.ibm.com>
> Sent: Thursday, May 16, 2024 2:07 PM
>
> Hi Salil,
>
> On 5/16/24 17:42, Salil Mehta wrote:
> > Hi Harsh,
> >
> >> From: Harsh Prateek Bora <hars...@linux.ibm.com>
> >> Sent: Thursday, May 16, 2024 11:15 AM
> >>
> >> Hi Salil,
> >>
> >> Thanks for your email.
> >> Your patch 1/8 is included here based on review comments on my previous
> >> patch from one of the maintainers in the community and therefore I had
> >> kept you in CC to be aware of the desire of having this independent
> patch to
> >> get merged earlier even if your other patches in the series may go
> through
> >> further reviews.
> >
> > I really don’t know which discussion are you pointing at? Please
> > understand you are fixing a bug and we are pushing a feature which has got
> large series.
> > It will break the patch-set which is about t be merged.
> >
> > There will be significant overhead of testing on us for the work we
> > have been carrying forward for large time. This will be disruptive. Please
> dont!
> >
>
> I was referring to the review discussion on my prev patch here:
> https://lore.kernel.org/qemu-devel/d191d2jfar7l.2eh4s445m4...@gmail.com/
Sure, I'm, not sure what this means.
> Although your patch was included with this series only to facilitate review
> of
> the additional patches depending on just one of your patch.
Generally you rebase your patch-set over the other and clearly state on the
cover
letter that this patch-set is dependent upon such and such patch-set. Just
imagine
if everyone starts to unilaterally pick up patches from each other's patch-set
it will
create a chaos not only for the feature owners but also for the maintainers.
>
> I am not sure what is appearing disruptive here. It is a common practive in
> the community that maintainer(s) can pick individual patches from the
> series if it has been vetted by siginificant number of reviewers.
Don’t you think this patch-set is asking for acceptance for a patch already
part of another patch-set which is about to be accepted and is a bigger feature?
Will it cause maintenance overhead at the last moment? Yes, of course!
> However, in this case, since you have mentioned to post next version soon,
> you need not worry about it as that would be the preferred version for both
> of the series.
Yes, but please understand we are working for the benefit of overall community.
Please cooperate here.
>
> >
> >>
> >> I am hoping to see your v9 soon and thereafter maintainer(s) may
> choose to
> >> pick the latest independent patch if needs to be merged earlier.
> >
> >
> > I don’t think you are understanding what problem it is causing. For
> > your small bug fix you are causing significant delays at our end.
> >
>
> I hope I clarfied above that including your patch here doesnt delay anything.
> Hoping to see your v9 soon!
>
> Thanks
> Harsh
> >
> > Thanks
> > Salil.
> >>
> >> Thanks for your work and let's be hopeful it gets merged soon.
> >>
> >> regards,
> >> Harsh
> >>
> >> On 5/16/24 14:00, Salil Mehta wrote:
> >> > Hi Harsh,
> >> >
> >> > Thanks for your interest in the patch-set but taking away patches like
> >> > this from other series without any discussion can disrupt others work
> >> > and its acceptance on time. This is because we will have to put lot of
> >> > effort in rebasing bigger series and then testing overhead comes
> along
> >> > with it.
> >> >
> >> > The patch-set (from where this patch has been taken) is part of even
> >> > bigger series and there have been many people and companies toiling
> to
> >> > fix the bugs collectively in that series and for years.
> >> >
> >> > I'm about float the V9 version of the Arch agnostic series which this
> >> > patch is part of and you can rebase your patch-set from there. I'm
> >> > hopeful that it will get accepted in this cycle.
> >> >
> >> >
> >> > Many thanks
> >> > Salil.
> >> >
> >> >> From: Harsh Prateek Bora <hars...@linux.ibm.com>
> >> >> Sent: Thursday, May 16, 2024 6:32 AM
> >> >>
> >> >> From: Salil Mehta <salil.me...@huawei.com>
> >> >>
> >> >> 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>
> >> >> [harshpb: fixed rebase failures in include/sysemu/kvm.h]
> >> >> Signed-off-by: Harsh Prateek Bora <hars...@linux.ibm.com>
> >> >> ---
> >> >> include/sysemu/kvm.h | 15 ++++++++++
> >> >> accel/kvm/kvm-all.c | 64
> ++++++++++++++++++++++++++++++++---
> >> -----
> >> >> --
> >> >> accel/kvm/trace-events | 5 +++-
> >> >> 3 files changed, 68 insertions(+), 16 deletions(-)
> >> >>
> >> >> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index
> >> >> eaf801bc93..fa3ec74442 100644
> >> >> --- a/include/sysemu/kvm.h
> >> >> +++ b/include/sysemu/kvm.h
> >> >> @@ -434,6 +434,21 @@ 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 /* COMPILING_PER_TARGET */
> >> >>
> >> >> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index
> >> >> d7281b93f3..30d42847de 100644
> >> >> --- a/accel/kvm/kvm-all.c
> >> >> +++ b/accel/kvm/kvm-all.c
> >> >> @@ -128,6 +128,7 @@ 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) { @@ -340,14
> >> +341,53
> >> >> @@ 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) {
> >> >> @@ -373,10 +413,7 @@ 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;
> >> >> }
> >> >> @@ -397,6 +434,8 @@ 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);
> >> >> @@ -404,7 +443,7 @@ 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) @@ -415,19
> +454,14
> >> @@
> >> >> 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/trace-events b/accel/kvm/trace-events index
> >> >> 681ccb667d..75c1724e78 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) ""
> >> >> --
> >> >> 2.39.3
> >> >
