Re: [PATCH v9 04/19] KVM: selftests: Expose function to allocate guest vCPU stack

[Sagi Shahar <sagis@google.com>]

On Thu, Aug 21, 2025 at 4:58 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> Sagi Shahar wrote:
>
> [snip]
>
> > diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> > index b2a4b11ac8c0..1eae92957456 100644
> > --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> > @@ -687,12 +687,9 @@ void vcpu_arch_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
> >       vcpu_regs_set(vcpu, &regs);
> >  }
> >
> > -struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
> > +vm_vaddr_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
> >  {
> > -     struct kvm_mp_state mp_state;
> > -     struct kvm_regs regs;
> >       vm_vaddr_t stack_vaddr;
> > -     struct kvm_vcpu *vcpu;
> >
> >       stack_vaddr = __vm_vaddr_alloc(vm, DEFAULT_STACK_PGS * getpagesize(),
> >                                      DEFAULT_GUEST_STACK_VADDR_MIN,
> > @@ -713,6 +710,15 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
> >                   "__vm_vaddr_alloc() did not provide a page-aligned address");
> >       stack_vaddr -= 8;
> >
> > +     return stack_vaddr;
> > +}
> > +
> > +struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
> > +{
> > +     struct kvm_mp_state mp_state;
> > +     struct kvm_regs regs;
> > +     struct kvm_vcpu *vcpu;
> > +
> >       vcpu = __vm_vcpu_add(vm, vcpu_id);
> >       vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
> >       vcpu_init_sregs(vm, vcpu);
> > @@ -721,7 +727,8 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
> >       /* Setup guest general purpose registers */
> >       vcpu_regs_get(vcpu, &regs);
> >       regs.rflags = regs.rflags | 0x2;
> > -     regs.rsp = stack_vaddr;
> > +     if (vm->type != KVM_X86_TDX_VM)
> > +             regs.rsp = kvm_allocate_vcpu_stack(vm);
>
> At this point in the series vm->type can't be KVM_X86_TDX_VM correct?
>
> So that makes this safe during bisect?
>

I double checked and no one is creating VMs with KVM_X86_TDX_VM. The
first test that sets KVM_X86_TDX_VM is the last patch in the series.

> Ira
>
> >       vcpu_regs_set(vcpu, &regs);
> >
> >       /* Setup the MP state */
> > --
> > 2.51.0.rc1.193.gad69d77794-goog
> >
>
>