diff options
Diffstat (limited to 'drivers/irqchip/irq-gic-v4.c')
| -rw-r--r-- | drivers/irqchip/irq-gic-v4.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c new file mode 100644 index 000000000..a6277dea4 --- /dev/null +++ b/drivers/irqchip/irq-gic-v4.c @@ -0,0 +1,392 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2016,2017 ARM Limited, All Rights Reserved. + * Author: Marc Zyngier <marc.zyngier@arm.com> + */ + +#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 + * device). Same goes for things like MAPC (the physical ITS deals + * with the actual vPE affinity, and not the braindead concept of + * collection). SYNC is not provided either, as each and every command + * is followed by a VSYNC. This could be relaxed in the future, should + * this be seen as a bottleneck (yes, this means *never*). + * + * But handling VLPIs is only one side of the job of the GICv4 + * code. The other (darker) side is to take care of the doorbell + * interrupts which are delivered when a VLPI targeting a non-running + * vcpu is being made pending. + * + * The choice made here is that each vcpu (VPE in old northern GICv4 + * dialect) gets a single doorbell LPI, no matter how many interrupts + * are targeting it. This has a nice property, which is that the + * interrupt becomes a handle for the VPE, and that the hypervisor + * code can manipulate it through the normal interrupt API: + * + * - VMs (or rather the VM abstraction that matters to the GIC) + * contain an irq domain where each interrupt maps to a VPE. In + * turn, this domain sits on top of the normal LPI allocator, and a + * specially crafted irq_chip implementation. + * + * - mask/unmask do what is expected on the doorbell interrupt. + * + * - irq_set_affinity is used to move a VPE from one redistributor to + * another. + * + * - irq_set_vcpu_affinity once again gets hijacked for the purpose of + * creating a new sub-API, namely scheduling/descheduling a VPE + * (which involves programming GICR_V{PROP,PEND}BASER) and + * performing INVALL operations. + */ + +static struct irq_domain *gic_domain; +static const struct irq_domain_ops *vpe_domain_ops; +static const struct irq_domain_ops *sgi_domain_ops; + +#ifdef CONFIG_ARM64 +#include <asm/cpufeature.h> + +bool gic_cpuif_has_vsgi(void) +{ + unsigned long fld, reg = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); + + fld = cpuid_feature_extract_unsigned_field(reg, ID_AA64PFR0_EL1_GIC_SHIFT); + + return fld >= 0x3; +} +#else +bool gic_cpuif_has_vsgi(void) +{ + return false; +} +#endif + +static bool has_v4_1(void) +{ + return !!sgi_domain_ops; +} + +static bool has_v4_1_sgi(void) +{ + return has_v4_1() && gic_cpuif_has_vsgi(); +} + +static int its_alloc_vcpu_sgis(struct its_vpe *vpe, int idx) +{ + char *name; + int sgi_base; + + if (!has_v4_1_sgi()) + return 0; + + name = kasprintf(GFP_KERNEL, "GICv4-sgi-%d", task_pid_nr(current)); + if (!name) + goto err; + + vpe->fwnode = irq_domain_alloc_named_id_fwnode(name, idx); + if (!vpe->fwnode) + goto err; + + kfree(name); + name = NULL; + + vpe->sgi_domain = irq_domain_create_linear(vpe->fwnode, 16, + sgi_domain_ops, vpe); + if (!vpe->sgi_domain) + goto err; + + sgi_base = __irq_domain_alloc_irqs(vpe->sgi_domain, -1, 16, + NUMA_NO_NODE, vpe, + false, NULL); + if (sgi_base <= 0) + goto err; + + return 0; + +err: + if (vpe->sgi_domain) + irq_domain_remove(vpe->sgi_domain); + if (vpe->fwnode) + irq_domain_free_fwnode(vpe->fwnode); + kfree(name); + return -ENOMEM; +} + +int its_alloc_vcpu_irqs(struct its_vm *vm) +{ + int vpe_base_irq, i; + + vm->fwnode = irq_domain_alloc_named_id_fwnode("GICv4-vpe", + task_pid_nr(current)); + if (!vm->fwnode) + goto err; + + vm->domain = irq_domain_create_hierarchy(gic_domain, 0, vm->nr_vpes, + vm->fwnode, vpe_domain_ops, + vm); + if (!vm->domain) + goto err; + + for (i = 0; i < vm->nr_vpes; i++) { + vm->vpes[i]->its_vm = vm; + vm->vpes[i]->idai = true; + } + + vpe_base_irq = __irq_domain_alloc_irqs(vm->domain, -1, vm->nr_vpes, + NUMA_NO_NODE, vm, + false, NULL); + if (vpe_base_irq <= 0) + goto err; + + for (i = 0; i < vm->nr_vpes; i++) { + int ret; + vm->vpes[i]->irq = vpe_base_irq + i; + ret = its_alloc_vcpu_sgis(vm->vpes[i], i); + if (ret) + goto err; + } + + return 0; + +err: + if (vm->domain) + irq_domain_remove(vm->domain); + if (vm->fwnode) + irq_domain_free_fwnode(vm->fwnode); + + return -ENOMEM; +} + +static void its_free_sgi_irqs(struct its_vm *vm) +{ + int i; + + if (!has_v4_1_sgi()) + return; + + for (i = 0; i < vm->nr_vpes; i++) { + unsigned int irq = irq_find_mapping(vm->vpes[i]->sgi_domain, 0); + + if (WARN_ON(!irq)) + continue; + + irq_domain_free_irqs(irq, 16); + irq_domain_remove(vm->vpes[i]->sgi_domain); + irq_domain_free_fwnode(vm->vpes[i]->fwnode); + } +} + +void its_free_vcpu_irqs(struct its_vm *vm) +{ + its_free_sgi_irqs(vm); + irq_domain_free_irqs(vm->vpes[0]->irq, vm->nr_vpes); + irq_domain_remove(vm->domain); + irq_domain_free_fwnode(vm->fwnode); +} + +static int its_send_vpe_cmd(struct its_vpe *vpe, struct its_cmd_info *info) +{ + return irq_set_vcpu_affinity(vpe->irq, info); +} + +int its_make_vpe_non_resident(struct its_vpe *vpe, bool db) +{ + struct irq_desc *desc = irq_to_desc(vpe->irq); + struct its_cmd_info info = { }; + int ret; + + WARN_ON(preemptible()); + + info.cmd_type = DESCHEDULE_VPE; + if (has_v4_1()) { + /* GICv4.1 can directly deal with doorbells */ + info.req_db = db; + } else { + /* Undo the nested disable_irq() calls... */ + while (db && irqd_irq_disabled(&desc->irq_data)) + enable_irq(vpe->irq); + } + + ret = its_send_vpe_cmd(vpe, &info); + if (!ret) + vpe->resident = false; + + vpe->ready = false; + + return ret; +} + +int its_make_vpe_resident(struct its_vpe *vpe, bool g0en, bool g1en) +{ + struct its_cmd_info info = { }; + int ret; + + WARN_ON(preemptible()); + + info.cmd_type = SCHEDULE_VPE; + if (has_v4_1()) { + info.g0en = g0en; + info.g1en = g1en; + } else { + /* Disabled the doorbell, as we're about to enter the guest */ + disable_irq_nosync(vpe->irq); + } + + ret = its_send_vpe_cmd(vpe, &info); + if (!ret) + vpe->resident = true; + + return ret; +} + +int its_commit_vpe(struct its_vpe *vpe) +{ + struct its_cmd_info info = { + .cmd_type = COMMIT_VPE, + }; + int ret; + + WARN_ON(preemptible()); + + ret = its_send_vpe_cmd(vpe, &info); + if (!ret) + vpe->ready = true; + + return ret; +} + + +int its_invall_vpe(struct its_vpe *vpe) +{ + struct its_cmd_info info = { + .cmd_type = INVALL_VPE, + }; + + return its_send_vpe_cmd(vpe, &info); +} + +int its_map_vlpi(int irq, struct its_vlpi_map *map) +{ + struct its_cmd_info info = { + .cmd_type = MAP_VLPI, + { + .map = map, + }, + }; + int ret; + + /* + * The host will never see that interrupt firing again, so it + * is vital that we don't do any lazy masking. + */ + irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY); + + ret = irq_set_vcpu_affinity(irq, &info); + if (ret) + irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY); + + return ret; +} + +int its_get_vlpi(int irq, struct its_vlpi_map *map) +{ + struct its_cmd_info info = { + .cmd_type = GET_VLPI, + { + .map = map, + }, + }; + + return irq_set_vcpu_affinity(irq, &info); +} + +int its_unmap_vlpi(int irq) +{ + irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY); + return irq_set_vcpu_affinity(irq, NULL); +} + +int its_prop_update_vlpi(int irq, u8 config, bool inv) +{ + struct its_cmd_info info = { + .cmd_type = inv ? PROP_UPDATE_AND_INV_VLPI : PROP_UPDATE_VLPI, + { + .config = config, + }, + }; + + return irq_set_vcpu_affinity(irq, &info); +} + +int its_prop_update_vsgi(int irq, u8 priority, bool group) +{ + struct its_cmd_info info = { + .cmd_type = PROP_UPDATE_VSGI, + { + .priority = priority, + .group = group, + }, + }; + + return irq_set_vcpu_affinity(irq, &info); +} + +int its_init_v4(struct irq_domain *domain, + const struct irq_domain_ops *vpe_ops, + const struct irq_domain_ops *sgi_ops) +{ + if (domain) { + pr_info("ITS: Enabling GICv4 support\n"); + gic_domain = domain; + vpe_domain_ops = vpe_ops; + sgi_domain_ops = sgi_ops; + return 0; + } + + pr_err("ITS: No GICv4 VPE domain allocated\n"); + return -ENODEV; +} |