On 16.07.2016 11:22, Marc Zyngier wrote:
> On Sat, 16 Jul 2016 04:33:59 +0300
> Alexander Popov <alex.po...@linux.com> wrote:
>
>> On 08.07.2016 11:34, Alexander Popov wrote:
>>> On 06.07.2016 14:17, Thomas Gleixner wrote:
>>>> On Fri, 1 Jul 2016, Alexander Popov wrote:
>>>>
>>>>> Export __irq_domain_alloc_irqs() and irq_domain_free_irqs() for being
>>>>> able to work with irq_domain hierarchy in modules.
>>>>
>>>> We usually export only when we have a proper use case which is supposed to
>>>> go
>>>> into the kernel tree proper. What's yours?
...
>> Did I properly answer your question? Will you accept my patch exporting these
>> two functions?
>
> I think that without any in-tree modular users of these symbols, the
> incentive for exporting those is pretty low. I can't really say
> anything about your particular use-case, but I'd really to see some
> code before taking that kind of patch.
Thanks for your answer, Mark.
Here is the module which uses __irq_domain_alloc_irqs() and
irq_domain_free_irqs() and allows registering IRQ handlers for interrupts
injected by the hypervisor on x86_64. Large hypervisors usually emulate
an MSI-capable PCI device to do this job, but that way is inappropriate
for lightweight hypervisors.
/*
* The module is for registering IRQ handlers for interrupts injected
* by the hypervisor using Intel VT-x technology. This module targets
* x86_64 platform.
*
* It works fine if __irq_domain_alloc_irqs() and irq_domain_free_irqs()
* are exported.
*/
#include <linux/module.h>
#include <linux/irq.h>
#include <linux/irqdesc.h>
#include <linux/irqnr.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <asm/hw_irq.h>
#include <asm/irqdomain.h>
#define PARAVIRT_IRQS_N 10
struct irq_domain *paravirq_domain = NULL;
static int paravirq_irqbase = -EINVAL;
static int paravirq_irqs[PARAVIRT_IRQS_N] =
{[0 ... PARAVIRT_IRQS_N - 1] = -EINVAL};
static irqreturn_t paravirq_irq_handler(int irq, void *cookie)
{
printk("\tparavirq_irq_handler: virq %d\n", irq);
/* ... some job ... */
return IRQ_HANDLED;
}
static void paravirq_chip_irq_mask(struct irq_data *data)
{
printk("\tparavirq_chip_irq_mask\n");
/* ... tell the hypervisor not to inject the interrupt ... */
}
static void paravirq_chip_irq_unmask(struct irq_data *data)
{
printk("\tparavirq_chip_irq_UNmask\n");
/* ... allow the hypervisor to inject the interrupt ... */
}
static void paravirq_chip_ack(struct irq_data *data)
{
data = data->parent_data;
data->chip->irq_ack(data);
}
static struct irq_chip paravirq_chip __read_mostly = {
.name = "PARAVIRQ",
.irq_mask = paravirq_chip_irq_mask,
.irq_unmask = paravirq_chip_irq_unmask,
.irq_ack = paravirq_chip_ack,
};
static int paravirq_domain_alloc(struct irq_domain *domain,
unsigned int virq, unsigned int nr_irqs, void *arg)
{
int ret = 0;
unsigned int i = 0;
unsigned int irq = 0;
printk("\tparavirq_domain_alloc: virq %u, nr_irqs %u, arg 0x%p\n",
virq, nr_irqs, arg);
for (i = 0; i < nr_irqs; i++) {
irq = virq + i;
ret = irq_domain_set_hwirq_and_chip(domain,
irq, i, ¶virq_chip, NULL);
if (ret) {
printk("\t\tsetting chip, hwirq for %d failed\n", irq);
return ret;
}
__irq_set_handler(irq, handle_edge_irq, 0, "edge");
}
return 0;
}
static void paravirq_domain_free(struct irq_domain *domain, unsigned int virq,
unsigned int nr_irqs)
{
int ret = 0;
unsigned int i = 0;
unsigned int irq = 0;
printk("\tparavirq_domain_free: virq %u, nr_irqs %u\n", virq, nr_irqs);
for (i = 0; i < nr_irqs; i++) {
irq = virq + i;
ret = irq_set_chip(irq, NULL);
if (ret)
printk("\t\tunsetting chip for %d failed\n", irq);
}
}
const struct irq_domain_ops paravirq_irqdomain_ops = {
.alloc = paravirq_domain_alloc,
.free = paravirq_domain_free,
};
static int __init paravirq_init(void)
{
int ret = 0;
int i = 0;
struct irq_alloc_info info = { 0 };
struct irq_cfg *cfg = NULL;
printk("paravirq_init\n");
paravirq_domain = irq_domain_add_linear(NULL, PARAVIRT_IRQS_N,
¶virq_irqdomain_ops, NULL);
if (!paravirq_domain) {
ret = -ENOMEM;
goto err0;
}
paravirq_domain->name = paravirq_chip.name;
paravirq_domain->parent = x86_vector_domain;
paravirq_domain->flags |= IRQ_DOMAIN_FLAG_AUTO_RECURSIVE;
printk("\tparavirq_domain %s (0x%p) is created\n",
paravirq_domain->name, paravirq_domain);
printk("\tcall irq_domain_alloc_irqs with info 0x%p\n", &info);
paravirq_irqbase = irq_domain_alloc_irqs(paravirq_domain,
PARAVIRT_IRQS_N, NUMA_NO_NODE, &info);
if (paravirq_irqbase < 0) {
printk("\tallocating irqs failed: %d\n", paravirq_irqbase);
ret = paravirq_irqbase;
goto err1;
}
printk("\tsuccessfully allocated %d irqs beginning from %d\n",
PARAVIRT_IRQS_N, paravirq_irqbase);
for (i = 0; i < PARAVIRT_IRQS_N; i++) {
int irq = paravirq_irqbase + i;
ret = request_irq(irq, paravirq_irq_handler,
0, "paravirq_mod", NULL);
if (ret) {
printk("\trequest_irq %d failed: %d\n", irq, ret);
goto err2;
} else {
printk("\tvirq %d is requested!\n", irq);
paravirq_irqs[i] = irq;
}
}
printk("\tSo, paravirq_mod grabbed %d irqs:\n", PARAVIRT_IRQS_N);
for (i = 0; i < PARAVIRT_IRQS_N; i++) {
cfg = irqd_cfg(irq_get_irq_data(paravirq_irqs[i]));
if (!cfg) {
printk("\t\tirq #%d: NULL irq_cfg\n", paravirq_irqs[i]);
goto err2;
}
printk("\t\tirq #%d: virq %d, vector %d\n",
i, paravirq_irqs[i], cfg->vector);
}
return 0;
err2:
for (i = 0; i < PARAVIRT_IRQS_N; i++) {
if (paravirq_irqs[i] >= 0) {
printk("\tfreeing virq %d\n", paravirq_irqs[i]);
free_irq(paravirq_irqs[i], NULL);
}
}
irq_domain_free_irqs(paravirq_irqbase, PARAVIRT_IRQS_N);
err1:
irq_domain_remove(paravirq_domain);
err0:
return ret;
}
static void __exit paravirq_exit(void)
{
int i;
printk("paravirq_exit\n");
for (i = 0; i < PARAVIRT_IRQS_N; i++) {
if (paravirq_irqs[i] > 0) {
printk("\tfreeing virq %d\n", paravirq_irqs[i]);
free_irq(paravirq_irqs[i], NULL);
}
}
if (paravirq_irqbase >= 0)
irq_domain_free_irqs(paravirq_irqbase, PARAVIRT_IRQS_N);
if (paravirq_domain)
irq_domain_remove(paravirq_domain);
}
module_init(paravirq_init)
module_exit(paravirq_exit)
MODULE_AUTHOR("Alexander Popov <alex.po...@linux.com>");
MODULE_DESCRIPTION("The module for handling interrupts from the hypervisor");
MODULE_LICENSE("GPL v2");
