Re: [PATCH v7 1/4] irqchip: gic: Support hierarchy irq domain.

[Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On 2014/11/20 1:18, Marc Zyngier wrote:
> Hi Yingjoe,
> 
> On Wed, Nov 19 2014 at  2:14:08 pm GMT, Yingjoe Chen <yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> wrote:
>> Add support to use gic as a parent for stacked irq domain.
>>
>> Signed-off-by: Yingjoe Chen <yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
>> ---
>>  drivers/irqchip/Kconfig   |  1 +
>>  drivers/irqchip/irq-gic.c | 78 ++++++++++++++++++++++++++++++++---------------
>>  2 files changed, 55 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index b21f12f..7f34138 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -5,6 +5,7 @@ config IRQCHIP
>>  config ARM_GIC
>>  	bool
>>  	select IRQ_DOMAIN
>> +	select IRQ_DOMAIN_HIERARCHY
>>  	select MULTI_IRQ_HANDLER
>>  
>>  config GIC_NON_BANKED
>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>> index 38493ff..464dd53 100644
>> --- a/drivers/irqchip/irq-gic.c
>> +++ b/drivers/irqchip/irq-gic.c
>> @@ -788,17 +788,16 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
>>  {
>>  	if (hw < 32) {
>>  		irq_set_percpu_devid(irq);
>> -		irq_set_chip_and_handler(irq, &gic_chip,
>> -					 handle_percpu_devid_irq);
>> +		irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
>> +				    handle_percpu_devid_irq, NULL, NULL);
>>  		set_irq_flags(irq, IRQF_VALID | IRQF_NOAUTOEN);
>>  	} else {
>> -		irq_set_chip_and_handler(irq, &gic_chip,
>> -					 handle_fasteoi_irq);
>> +		irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
>> +				    handle_fasteoi_irq, NULL, NULL);
>>  		set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
>>  
>>  		gic_routable_irq_domain_ops->map(d, irq, hw);
>>  	}
>> -	irq_set_chip_data(irq, d->host_data);
>>  	return 0;
>>  }
>>  
>> @@ -858,6 +857,31 @@ static struct notifier_block gic_cpu_notifier = {
>>  };
>>  #endif
>>  
>> +static int gic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>> +				unsigned int nr_irqs, void *arg)
>> +{
>> +	int i, ret;
>> +	irq_hw_number_t hwirq;
>> +	unsigned int type = IRQ_TYPE_NONE;
>> +	struct of_phandle_args *irq_data = arg;
>> +
>> +	ret = gic_irq_domain_xlate(domain, irq_data->np, irq_data->args,
>> +				   irq_data->args_count, &hwirq, &type);
>> +	if (ret)
>> +		return ret;
>> +
>> +	for (i = 0; i < nr_irqs; i++)
>> +		gic_irq_domain_map(domain, virq+i, hwirq+i);
> 
> nit: spacing around '+'.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct irq_domain_ops gic_irq_domain_hierarchy_ops = {
>> +	.xlate = gic_irq_domain_xlate,
>> +	.alloc = gic_irq_domain_alloc,
>> +	.free = irq_domain_free_irqs_top,
> 
> I'm convinced that irq_domain_free_irqs_top is the wrong function to
> call here, because you're calling it from the bottom, not the top-level
> (it has no parent).
> 
> I cannot verify this with your code as I don't a working platform with
> GICv2m, but if I enable something similar on GICv3, it dies a very
> painful way:
> 
> Unable to handle kernel NULL pointer dereference at virtual address 00000018
> pgd = ffffffc03d059000
> [00000018] *pgd=0000000081356003, *pud=0000000081356003, *pmd=0000000000000000
> Internal error: Oops: 96000006 [#1] SMP
> Modules linked in:
> CPU: 4 PID: 1052 Comm: sh Not tainted 3.18.0-rc4+ #3311
> task: ffffffc03e320000 ti: ffffffc001390000 task.ti: ffffffc001390000
> PC is at irq_domain_free_irqs_recursive+0x1c/0x80
> LR is at irq_domain_free_irqs_common+0x88/0x9c
> pc : [<ffffffc0000ed790>] lr : [<ffffffc0000ede20>] pstate: 60000145
> [...]
> [<ffffffc0000ed790>] irq_domain_free_irqs_recursive+0x1c/0x80
> [<ffffffc0000ede1c>] irq_domain_free_irqs_common+0x84/0x9c
> [<ffffffc0000ede98>] irq_domain_free_irqs_top+0x64/0x7c  <-- gic_domain.free()
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ee468>] irq_domain_free_irqs_parent+0x14/0x20
> [<ffffffc0003500b8>] its_irq_domain_free+0xc8/0x250
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ede1c>] irq_domain_free_irqs_common+0x84/0x9c
> [<ffffffc0000ede98>] irq_domain_free_irqs_top+0x64/0x7c
> [<ffffffc0000ef518>] msi_domain_free+0x70/0x88
> [<ffffffc0000ed798>] irq_domain_free_irqs_recursive+0x24/0x80
> [<ffffffc0000ee3ac>] irq_domain_free_irqs+0x108/0x17c
> [<ffffffc0000efb68>] msi_domain_free_irqs+0x28/0x4c
> [<ffffffc000369cac>] free_msi_irqs+0xb4/0x1c0
> [<ffffffc00036adec>] pci_disable_msix+0x3c/0x4c
> [...]
> 
> and I cannot see how this could work on the standard GIC either.
> 
> Thomas, Jiang: could you please confirm or infirm my suspicions? My
> understanding is that irq_domain_free_irqs_top can only be called from
> the top-level domain.
Hi Marc,
	It indicates that irq_domain_free_irqs_top() is not a good name.
We have:
1) irq_domain_set_hwirq_and_chip() to set irq_chip and chip_data
2) irq_domain_set_info() to set irq_chip, chip_data, flow_handler and
   handler_data;
3) irq_domain_reset_irq_data() resets irq_chip and chip_data.
4) irq_domain_free_irqs_common() resets irq_chip, chip_data and calls
   parent domain's domain_ops.free() callback.
5) irq_domain_free_irqs_top() resets irq_chip, chip_data, flow handler,
   handler_data and call parent domain's domain_ops.free() callback.

So there two possible improvements here:
1) Rename irq_domain_free_irqs_top() with better name, any suggestions?
   It's named as is because it's always called by the outer-most
   irqdomains on x86.
2) Change irq_domain_free_irqs_common() and irq_domain_free_irqs_top()
   to call parent domain's domain_ops.free() callback only if parent
   exists. By this way, they could be used for inner-most irqdomains.
If OK, I will respin a version 4 patch set based on tip/irq/irqdomain.
Thoughts?
Regards!
Gerry
> 
>> +};
>> +
>>  static const struct irq_domain_ops gic_irq_domain_ops = {
>>  	.map = gic_irq_domain_map,
>>  	.unmap = gic_irq_domain_unmap,
>> @@ -948,18 +972,6 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>  		gic_cpu_map[i] = 0xff;
>>  
>>  	/*
>> -	 * For primary GICs, skip over SGIs.
>> -	 * For secondary GICs, skip over PPIs, too.
>> -	 */
>> -	if (gic_nr == 0 && (irq_start & 31) > 0) {
>> -		hwirq_base = 16;
>> -		if (irq_start != -1)
>> -			irq_start = (irq_start & ~31) + 16;
>> -	} else {
>> -		hwirq_base = 32;
>> -	}
>> -
>> -	/*
>>  	 * Find out how many interrupts are supported.
>>  	 * The GIC only supports up to 1020 interrupt sources.
>>  	 */
>> @@ -969,10 +981,32 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>  		gic_irqs = 1020;
>>  	gic->gic_irqs = gic_irqs;
>>  
>> -	gic_irqs -= hwirq_base; /* calculate # of irqs to allocate */
>> +	if (node) {		/* DT case */
>> +		const struct irq_domain_ops *ops =
>> +					&gic_irq_domain_hierarchy_ops;
> 
> nit: please put this on the same line, even if it is longer than 80
> characters.
> 
>> +
>> +		if (!of_property_read_u32(node, "arm,routable-irqs",
>> +					  &nr_routable_irqs)) {
>> +			ops = &gic_irq_domain_ops;
>> +			gic_irqs = nr_routable_irqs;
>> +		}
>> +
>> +		gic->domain = irq_domain_add_linear(node, gic_irqs, ops, gic);
>> +	} else {		/* Non-DT case */
>> +		/*
>> +		 * For primary GICs, skip over SGIs.
>> +		 * For secondary GICs, skip over PPIs, too.
>> +		 */
>> +		if (gic_nr == 0 && (irq_start & 31) > 0) {
>> +			hwirq_base = 16;
>> +			if (irq_start != -1)
>> +				irq_start = (irq_start & ~31) + 16;
>> +		} else {
>> +			hwirq_base = 32;
>> +		}
>> +
>> +		gic_irqs -= hwirq_base; /* calculate # of irqs to allocate */
>>  
>> -	if (of_property_read_u32(node, "arm,routable-irqs",
>> -				 &nr_routable_irqs)) {
>>  		irq_base = irq_alloc_descs(irq_start, 16, gic_irqs,
>>  					   numa_node_id());
>>  		if (IS_ERR_VALUE(irq_base)) {
>> @@ -983,10 +1017,6 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>  
>>  		gic->domain = irq_domain_add_legacy(node, gic_irqs, irq_base,
>>  					hwirq_base, &gic_irq_domain_ops, gic);
>> -	} else {
>> -		gic->domain = irq_domain_add_linear(node, nr_routable_irqs,
>> -						    &gic_irq_domain_ops,
>> -						    gic);
>>  	}
>>  
>>  	if (WARN_ON(!gic->domain))
> 
> Thanks,
> 
> 	M.
> 
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