linux-imx

/*

 * Copyright (C) 2016,2017 ARM Limited, All Rights Reserved.

 * Author: Marc Zyngier <marc.zyngier@arm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

​

#include <linux/interrupt.h>

#include <linux/irq.h>

#include <linux/irqdomain.h>

#include <linux/msi.h>

#include <linux/sched.h>

​

#include <linux/irqchip/arm-gic-v4.h>

​

/*

 * WARNING: The blurb below assumes that you understand the

 * intricacies of GICv3, GICv4, and how a guest's view of a GICv3 gets

 * translated into GICv4 commands. So it effectively targets at most

 * two individuals. You know who you are.

 *

 * The core GICv4 code is designed to *avoid* exposing too much of the

 * core GIC code (that would in turn leak into the hypervisor code),

 * and instead provide a hypervisor agnostic interface to the HW (of

 * course, the astute reader will quickly realize that hypervisor

 * agnostic actually means KVM-specific - what were you thinking?).

 *

 * In order to achieve a modicum of isolation, we try to hide most of

 * the GICv4 "stuff" behind normal irqchip operations:

 *

 * - Any guest-visible VLPI is backed by a Linux interrupt (and a

 *   physical LPI which gets unmapped when the guest maps the

 *   VLPI). This allows the same DevID/EventID pair to be either

 *   mapped to the LPI (host) or the VLPI (guest). Note that this is

 *   exclusive, and you cannot have both.

 *

 * - Enabling/disabling a VLPI is done by issuing mask/unmask calls.

 *

 * - Guest INT/CLEAR commands are implemented through

 *   irq_set_irqchip_state().

 *

 * - The *bizarre* stuff (mapping/unmapping an interrupt to a VLPI, or

 *   issuing an INV after changing a priority) gets shoved into the

 *   irq_set_vcpu_affinity() method. While this is quite horrible

 *   (let's face it, this is the irqchip version of an ioctl), it

 *   confines the crap to a single location. And map/unmap really is

 *   about setting the affinity of a VLPI to a vcpu, so only INV is

 *   majorly out of place. So there.

 *

 * A number of commands are simply not provided by this interface, as

 * they do not make direct sense. For example, MAPD is purely local to

 * the virtual ITS (because it references a virtual device, and the

 * physical ITS is still very much in charge of the physical