[PATCH v2 2/2] powerpc/pci: unmap all interrupts when a PHB is removed

[Alexey Kardashevskiy]

On 18/06/2020 02:29, Cédric Le Goater wrote:
> Some PCI adapters, like GPUs, use the "interrupt-map" property to
> describe interrupt mappings other than the legacy INTx interrupts.
> There can be more than 4 mappings.
> 
> To clear all interrupts when a PHB is removed, we need to increase the
> 'irq_map' array in which mappings are recorded. Compute the number of
> interrupt mappings from the "interrupt-map" property and allocate a
> bigger 'irq_map' array.
> 
> Signed-off-by: Cédric Le Goater <clg at kaod.org>
> ---
>  arch/powerpc/kernel/pci-common.c | 49 +++++++++++++++++++++++++++++++-
>  1 file changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index 515480a4bac6..deb831f0ae13 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -353,9 +353,56 @@ struct pci_controller *pci_find_controller_for_domain(int domain_nr)
>  	return NULL;
>  }
>  
> +/*
> + * Assumption is made on the interrupt parent. All interrupt-map
> + * entries are considered to have the same parent.
> + */
> +static int pcibios_irq_map_count(struct pci_controller *phb)

I wonder if
int of_irq_count(struct device_node *dev)
could work here too. If it does not, then never mind.


Other than that, the only other comment is - merge this one into 1/2 as
1/2 alone won't properly fix the problem but it may look like that it does:

for phyp, the test machine just happens to have 4 entries in the map but
this is the phyp implementation detail;

for qemu, there are more but we only unregister 4 but kvm does not care
in general so it is ok which is also implementation detail;

and 2/2 just makes these details not matter. Thanks,



> +{
> +	const __be32 *imap;
> +	int imaplen;
> +	struct device_node *parent;
> +	u32 intsize, addrsize, parintsize, paraddrsize;
> +
> +	if (of_property_read_u32(phb->dn, "#interrupt-cells", &intsize))
> +		return 0;
> +	if (of_property_read_u32(phb->dn, "#address-cells", &addrsize))
> +		return 0;
> +
> +	imap = of_get_property(phb->dn, "interrupt-map", &imaplen);
> +	if (!imap) {
> +		pr_debug("%pOF : no interrupt-map\n", phb->dn);
> +		return 0;
> +	}
> +	imaplen /= sizeof(u32);
> +	pr_debug("%pOF : imaplen=%d\n", phb->dn, imaplen);
> +
> +	if (imaplen < (addrsize + intsize + 1))
> +		return 0;
> +
> +	imap += intsize + addrsize;
> +	parent = of_find_node_by_phandle(be32_to_cpup(imap));
> +	if (!parent) {
> +		pr_debug("%pOF : no imap parent found !\n", phb->dn);
> +		return 0;
> +	}
> +
> +	if (of_property_read_u32(parent, "#interrupt-cells", &parintsize)) {
> +		pr_debug("%pOF : parent lacks #interrupt-cells!\n", phb->dn);
> +		return 0;
> +	}
> +
> +	if (of_property_read_u32(parent, "#address-cells", &paraddrsize))
> +		paraddrsize = 0;
> +
> +	return imaplen / (addrsize + intsize + 1 + paraddrsize + parintsize);
> +}
> +
>  static void pcibios_irq_map_init(struct pci_controller *phb)
>  {
> -	phb->irq_count = PCI_NUM_INTX;
> +	phb->irq_count = pcibios_irq_map_count(phb);
> +	if (phb->irq_count < PCI_NUM_INTX)
> +		phb->irq_count = PCI_NUM_INTX;
>  
>  	pr_debug("%pOF : interrupt map #%d\n", phb->dn, phb->irq_count);
>  
> 

-- 
Alexey