RE: [patch V2 13/33] x86/apic/vector: Provide MSI parent domain

[Tian, Kevin]

> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Sent: Monday, November 21, 2022 10:38 PM
> 
> +bool pci_dev_has_default_msi_parent_domain(struct pci_dev *dev)
> +{
> +	struct irq_domain *domain = dev_get_msi_domain(&dev->dev);
> 
> -int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
> -		    msi_alloc_info_t *arg)
> +	if (!domain)
> +		domain = dev_get_msi_domain(&dev->bus->dev);
> +	if (!domain)
> +		return false;
> +
> +	return domain == x86_vector_domain;

the function name is about parent domain but there is no check on
the parent flag. Probably just remove 'parent'?

> +/**
> + * x86_init_dev_msi_info - Domain info setup for MSI domains
> + * @dev:		The device for which the domain should be created
> + * @domain:		The (root) domain providing this callback

what is the purpose of '(root)'? it's also used by intermediate domain i.e. IR.

> +
> +	/*
> +	 * Mask out the domain specific MSI feature flags which are not
> +	 * supported by the real parent.
> +	 */
> +	info->flags			&= pops->supported_flags;
> +	/* Enforce the required flags */
> +	info->flags			|=
> X86_VECTOR_MSI_FLAGS_REQUIRED;
> +
> +	/* This is always invoked from the top level MSI domain! */
> +	info->ops->msi_prepare		= x86_msi_prepare;
> +
> +	info->chip->irq_ack		= irq_chip_ack_parent;
> +	info->chip->irq_retrigger	= irq_chip_retrigger_hierarchy;
> +	info->chip->flags		|= IRQCHIP_SKIP_SET_WAKE |
> +					   IRQCHIP_AFFINITY_PRE_STARTUP;

Above are executed twice for both IR and vector after next patch comes.
Could skip it for IR.