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? > > Hello, Thomas, > > I work at Positive Technologies ( https://www.ptsecurity.com/ ). We develop > a bare-metal hypervisor, which targets x86_64 and supports Linux as a guest > OS. > > Intel VT-x allows hypervisor to inject interrupts into virtual machines. > We want to handle these interrupts in guest Linux. > > So I wrote a simple kernel module creating an irq_domain, which has > x86_vector_domain as a parent in the hierarchy. In this module I just call: > - irq_domain_alloc_irqs() to allocate irqs and allow calling request_irq() > for them; > - irqd_cfg(irq_get_irq_data()) to get the APIC vectors of the allocated irqs; > - irq_domain_free_irqs() to free the resources at the end. > > It allows to handle interrupts injected by the hypervisor in guest Linux > easily, > without emulating MSI-capable PCI device at the hypervisor side. > > Everything works fine if __irq_domain_alloc_irqs() and irq_domain_free_irqs() > are exported. Is it a proper use-case?
Hello again, Thomas, Did I properly answer your question? Will you accept my patch exporting these two functions? > Do you think my module could be useful for the mainline in some form? > It took me some time to understand irq_domain hierarchy design, so I can > prepare some patch or share my code to help others. Do you think my paravirtualization code registering a child irq_domain for x86_vector_domain could bring any profit to the mainline? I would be glad to put effort and do it. Thanks again, sorry for disturbing. Best regards, Alexander
