From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753389AbcGYTcy (ORCPT ); Mon, 25 Jul 2016 15:32:54 -0400 Received: from mail-lf0-f67.google.com ([209.85.215.67]:35016 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752148AbcGYTcw (ORCPT ); Mon, 25 Jul 2016 15:32:52 -0400 Reply-To: alex.popov@linux.com Subject: Re: [PATCH 1/1] irqdomain: Export __irq_domain_alloc_irqs() and irq_domain_free_irqs() References: <1467401388-11221-1-git-send-email-alex.popov@linux.com> <577F6578.6030904@linux.com> <57898F07.7030609@linux.com> <20160716092218.3a2de5c7@arm.com> <578CCCDB.4050800@linux.com> To: Marc Zyngier Cc: Thomas Gleixner , LKML , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Joerg Roedel , kvm@vger.kernel.org From: Alexander Popov Message-ID: <579669EB.6030604@linux.com> Date: Mon, 25 Jul 2016 22:35:07 +0300 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <578CCCDB.4050800@linux.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18.07.2016 15:34, Alexander Popov wrote: > On 16.07.2016 11:22, Marc Zyngier wrote: >> On Sat, 16 Jul 2016 04:33:59 +0300 >> Alexander Popov 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. I hope that the code below is a valid use-case of irq_domain hierarchy API. Such simple registration of IRQ handlers for interrupts injected by a hypervisor is great for lightweight hypervisors, which avoid as much emulation as possible. It only needs __irq_domain_alloc_irqs() and irq_domain_free_irqs() to be exported to modules. Will you apply my patch which exports them? [Add CC to KVM people to share the idea and, hopefully, find anybody interested] > /* > * The module 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 > #include > #include > #include > #include > #include > #include > #include > > #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 "); > MODULE_DESCRIPTION("The module for handling interrupts from the hypervisor"); > MODULE_LICENSE("GPL v2"); >