Re: [PATCH 1/7] PCI/TSM: Add pci_tsm_{bind,unbind}() methods for instantiating TDIs

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Alexey Kardashevskiy <aik@amd.com> writes:

> On 4/9/25 01:17, Aneesh Kumar K.V wrote:
>> Dan Williams <dan.j.williams@intel.com> writes:
>> ...
>> 
>>> +/**
>>> + * pci_tsm_bind() - Bind @pdev as a TDI for @kvm
>>> + * @pdev: PCI device function to bind
>>> + * @kvm: Private memory attach context
>>> + * @tdi_id: Identifier (virtual BDF) for the TDI as referenced by the TSM and DSM
>>> + *
>>> + * Returns 0 on success, or a negative error code on failure.
>>> + *
>>> + * Context: Caller is responsible for constraining the bind lifetime to the
>>> + * registered state of the device. For example, pci_tsm_bind() /
>>> + * pci_tsm_unbind() limited to the VFIO driver bound state of the device.
>>> + */
>>> +int pci_tsm_bind(struct pci_dev *pdev, struct kvm *kvm, u32 tdi_id)
>>> +{
>>> +	const struct pci_tsm_ops *ops;
>>> +	struct pci_tsm_pf0 *tsm_pf0;
>>> +	struct pci_tdi *tdi;
>>> +
>>> +	if (!kvm)
>>> +		return -EINVAL;
>>> +
>>> +	guard(rwsem_read)(&pci_tsm_rwsem);
>>> +
>>> +	if (!pdev->tsm)
>>> +		return -EINVAL;
>>> +
>>> +	ops = pdev->tsm->ops;
>>> +
>>> +	if (!is_link_tsm(ops->owner))
>>> +		return -ENXIO;
>>> +
>>> +	tsm_pf0 = to_pci_tsm_pf0(pdev->tsm);
>>> +	guard(mutex)(&tsm_pf0->lock);
>>> +
>>> +	/* Resolve races to bind a TDI */
>>> +	if (pdev->tsm->tdi) {
>>> +		if (pdev->tsm->tdi->kvm == kvm)
>>> +			return 0;
>>> +		else
>>> +			return -EBUSY;
>>> +	}
>>> +
>>> +	tdi = ops->bind(pdev, kvm, tdi_id);
>>> +	if (IS_ERR(tdi))
>>> +		return PTR_ERR(tdi);
>>> +
>>> +	pdev->tsm->tdi = tdi;
>>> +
>>> +	return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(pci_tsm_bind);
>>> +
>> 
>> Are we missing assigning pdev and kvm in the above function?
>> 
>> modified   drivers/pci/tsm.c
>> @@ -356,6 +356,8 @@ int pci_tsm_bind(struct pci_dev *pdev, struct kvm *kvm, u32 tdi_id)
>>   	if (IS_ERR(tdi))
>>   		return PTR_ERR(tdi);
>>   
>> +	tdi->pdev = pdev;
>
> This signals that this pdev backref is not exactly needed :)
>

I need that in cca_tsm_unbind

static void cca_tsm_unbind(struct pci_tdi *tdi)
{
	struct realm *realm = &tdi->kvm->arch.realm;

	rme_unbind_vdev(realm, tdi->pdev, tdi->pdev->tsm->dsm);
	module_put(THIS_MODULE);
}


-aneesh