Re: [PATCH v3 24/25] KVM: TDX: Guard VM state transitions with "all" the locks

[Huang, Kai]

On Thu, 2025-10-16 at 17:32 -0700, Sean Christopherson wrote:
> @@ -2781,8 +2827,6 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
>  	if (r)
>  		return r;
>  
> -	guard(mutex)(&kvm->lock);
> -
>  	switch (tdx_cmd.id) {
>  	case KVM_TDX_CAPABILITIES:
>  		r = tdx_get_capabilities(&tdx_cmd);

IIRC, this patch removes grabbing the kvm->lock in tdx_vm_ioctl() but only
adds the "big hammer" to tdx_td_init() and tdx_td_finalize(), so the
tdx_get_capabilities() lost holding the kvm->lock.

As replied earlier, I think we can just hold the "big hammer" in
tdx_vm_ioctl()?

One thing is when tdx_vm_ioctl() is called, the TD may not have any vCPU
(e.g., for tdx_td_init()).  This means the "big hammer" will hold kvm-
>slots_lock w/o holding any lock of vCPU.  But IIUC this should be OK.