When we don't have the DirectLPI feature, we must work around the architecture shortcomings to be able to perform the required invalidation.
For this, we create a fake device whose sole purpose is to provide a way to issue a map/inv/unmap sequence (and the corresponding sync operations). That's 6 commands and a full serialization point to be able to do this. You just have hope the hypervisor won't do that too often... Signed-off-by: Marc Zyngier <[email protected]> --- drivers/irqchip/irq-gic-v3-its.c | 59 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 57 insertions(+), 2 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 008fb71..3787579 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -133,6 +133,9 @@ struct its_device { u32 device_id; }; +static struct its_device *vpe_proxy_dev; +static DEFINE_RAW_SPINLOCK(vpe_proxy_dev_lock); + static LIST_HEAD(its_nodes); static DEFINE_SPINLOCK(its_lock); static struct rdists *gic_rdists; @@ -993,8 +996,35 @@ static void lpi_update_config(struct irq_data *d, u8 clr, u8 set) struct its_vpe *vpe = irq_data_get_irq_chip_data(d); void __iomem *rdbase; - rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base; - writeq_relaxed(d->hwirq, rdbase + GICR_INVLPIR); + if (gic_rdists->has_direct_lpi) { + rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base; + writeq_relaxed(d->hwirq, rdbase + GICR_INVLPIR); + } else { + /* + * This is insane. + * + * If a GICv4 doesn't implement Direct LPIs, + * the only way to perform an invalidate is to + * use a fake device to issue a MAP/INV/UNMAP + * sequence. Since each of these commands has + * a sync operation, this is really fast. Not. + * + * We always use event 0, and this serialize + * all VPE invalidations in the system. + * + * Broken by design(tm). + */ + unsigned long flags; + + raw_spin_lock_irqsave(&vpe_proxy_dev_lock, flags); + + vpe_proxy_dev->event_map.col_map[0] = vpe->col_idx; + its_send_mapvi(vpe_proxy_dev, vpe->vpe_db_lpi, 0); + its_send_inv(vpe_proxy_dev, 0); + its_send_discard(vpe_proxy_dev, 0); + + raw_spin_unlock_irqrestore(&vpe_proxy_dev_lock, flags); + } } } @@ -2481,6 +2511,31 @@ static struct irq_domain *its_init_vpe_domain(void) struct fwnode_handle *handle; struct irq_domain *domain; + if (gic_rdists->has_direct_lpi) { + pr_info("ITS: Using DirectLPI for VPE invalidation\n"); + } else { + struct its_node *its; + + list_for_each_entry(its, &its_nodes, entry) { + u32 devid; + + if (!its->is_v4) + continue; + + /* Use the last possible DevID */ + devid = GENMASK(its->device_ids - 1, 0); + vpe_proxy_dev = its_create_device(its, devid, 1); + if (!vpe_proxy_dev) { + pr_err("ITS: Can't allocate GICv4 proxy device\n"); + return NULL; + } + + pr_info("ITS: Allocated DevID %x as GICv4 proxy device\n", + devid); + break; + } + } + handle = irq_domain_alloc_fwnode("VPE domain"); if (!handle) return NULL; -- 2.1.4
