Re: [PATCH 0/5] KVM: Serialize vCPU creation and revert vcpu_ids tracking

[Sean Christopherson <seanjc@google.com>]

On Mon, Sep 21, 2026, Paolo Bonzini wrote:
> On 9/21/26 15:57, Thorsten Leemhuis wrote:
> > On 9/14/26 20:12, Sean Christopherson wrote:
> > > Serialize vCPU creation by holding kvm->lock for the entirety of
> > > kvm_vm_ioctl_create_vcpu(), and then revert the now-redundant tracking adding
> > > by commit 97d65b544f48 ("KVM: Check for duplicate vcpu_id as early as
> > > possible").  I botched the math when justifying the vcpu_ids tracking; it's not
> > > an extra 256 bytes, it's an extra 2048 bytes.  Roughly doubling the size of
> > > "struct kvm" tripped x86's KVM_SANITY_CHECK_VM_STRUCT_SIZE, and obviously isn't
> > > something we want to do in general.
> > 
> > Hi Sean! Thx for handling this and sorry for pestering you, but I have
> > to ask, as this fixes a regression that was already reported two times
> > and introduced this cycle:
> > 
> > What's the plan to merge this? Is this aimed for the current or the next
> > merge window? Ciao, Thorsten
> 
> For this one, but after fixing the PPC and s390 cases.

Ya.

> Sean, if you're busy I can send the v2 myself.

I'll get it out today.  I was traveling last week and got behind one a "few" things.