irqchip/gic-v3-its: Plug allocation race for devices sharing a DevID
On systems or VMs where multiple devices share a single DevID (because they sit behind a PCI bridge, or because the HW is broken in funky ways), we reuse the save its_device structure in order to reflect this. It turns out that there is a distinct lack of locking when looking up the its_device, and two device being probed concurrently can result in double allocations. That's obviously not nice. A solution for this is to have a per-ITS mutex that serializes device allocation. A similar issue exists on the freeing side, which can run concurrently with the allocation. On top of now taking the appropriate lock, we also make sure that a shared device is never freed, as we have no way to currently track the life cycle of such object. Reported-by: Zheng Xiang <zhengxiang9@huawei.com> Tested-by: Zheng Xiang <zhengxiang9@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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@ -97,9 +97,14 @@ struct its_device;
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* The ITS structure - contains most of the infrastructure, with the
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* top-level MSI domain, the command queue, the collections, and the
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* list of devices writing to it.
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*
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* dev_alloc_lock has to be taken for device allocations, while the
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* spinlock must be taken to parse data structures such as the device
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* list.
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*/
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struct its_node {
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raw_spinlock_t lock;
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struct mutex dev_alloc_lock;
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struct list_head entry;
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void __iomem *base;
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phys_addr_t phys_base;
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@ -156,6 +161,7 @@ struct its_device {
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void *itt;
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u32 nr_ites;
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u32 device_id;
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bool shared;
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};
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static struct {
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@ -2469,6 +2475,7 @@ static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
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struct its_device *its_dev;
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struct msi_domain_info *msi_info;
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u32 dev_id;
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int err = 0;
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/*
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* We ignore "dev" entierely, and rely on the dev_id that has
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@ -2491,6 +2498,7 @@ static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
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return -EINVAL;
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}
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mutex_lock(&its->dev_alloc_lock);
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its_dev = its_find_device(its, dev_id);
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if (its_dev) {
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/*
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@ -2498,18 +2506,22 @@ static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
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* another alias (PCI bridge of some sort). No need to
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* create the device.
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*/
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its_dev->shared = true;
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pr_debug("Reusing ITT for devID %x\n", dev_id);
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goto out;
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}
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its_dev = its_create_device(its, dev_id, nvec, true);
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if (!its_dev)
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return -ENOMEM;
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if (!its_dev) {
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err = -ENOMEM;
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goto out;
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}
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pr_debug("ITT %d entries, %d bits\n", nvec, ilog2(nvec));
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out:
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mutex_unlock(&its->dev_alloc_lock);
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info->scratchpad[0].ptr = its_dev;
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return 0;
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return err;
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}
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static struct msi_domain_ops its_msi_domain_ops = {
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@ -2613,6 +2625,7 @@ static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
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{
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struct irq_data *d = irq_domain_get_irq_data(domain, virq);
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struct its_device *its_dev = irq_data_get_irq_chip_data(d);
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struct its_node *its = its_dev->its;
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int i;
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for (i = 0; i < nr_irqs; i++) {
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@ -2627,8 +2640,14 @@ static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
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irq_domain_reset_irq_data(data);
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}
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/* If all interrupts have been freed, start mopping the floor */
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if (bitmap_empty(its_dev->event_map.lpi_map,
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mutex_lock(&its->dev_alloc_lock);
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/*
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* If all interrupts have been freed, start mopping the
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* floor. This is conditionned on the device not being shared.
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*/
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if (!its_dev->shared &&
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bitmap_empty(its_dev->event_map.lpi_map,
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its_dev->event_map.nr_lpis)) {
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its_lpi_free(its_dev->event_map.lpi_map,
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its_dev->event_map.lpi_base,
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@ -2640,6 +2659,8 @@ static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
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its_free_device(its_dev);
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}
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mutex_unlock(&its->dev_alloc_lock);
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irq_domain_free_irqs_parent(domain, virq, nr_irqs);
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}
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@ -3549,6 +3570,7 @@ static int __init its_probe_one(struct resource *res,
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}
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raw_spin_lock_init(&its->lock);
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mutex_init(&its->dev_alloc_lock);
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INIT_LIST_HEAD(&its->entry);
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INIT_LIST_HEAD(&its->its_device_list);
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typer = gic_read_typer(its_base + GITS_TYPER);
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