Re: [PATCH v2 21/24] KVM: TDX: Add an ioctl to create initial guest memory

[Yan Zhao <yan.y.zhao@intel.com>]

On Wed, Nov 27, 2024 at 08:08:26PM +0200, Nikolay Borisov wrote:
> 
> On 12.11.24 г. 9:38 ч., Yan Zhao wrote:
> > +static int tdx_vcpu_init_mem_region(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *cmd)
> > +{
> > +	struct vcpu_tdx *tdx = to_tdx(vcpu);
> > +	struct kvm *kvm = vcpu->kvm;
> > +	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> > +	struct kvm_tdx_init_mem_region region;
> > +	struct tdx_gmem_post_populate_arg arg;
> > +	long gmem_ret;
> > +	int ret;
> > +
> > +	if (tdx->state != VCPU_TD_STATE_INITIALIZED)
> > +		return -EINVAL;
> > +
> > +	guard(mutex)(&kvm->slots_lock);
> 
> It seems the scope of this lock can be reduced. It's really needed for the
> kvm_gmem_populate call only, no ?
Strictly speaking, yes.
But this KVM_TDX_INIT_MEM_REGION ioctl is only expected to be executed after
QEMU machine creation done and before any vCPU starts running. So no slot
changes are expected during the ioctl.