Messages in this thread | | | Date | Mon, 15 Nov 2021 20:05:17 +0100 | Subject | Re: [PATCH 16/39] irqdomain: Make normal and nomap irqdomains exclusive | From | Cédric Le Goater <> |
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Hello Mark,
On 5/20/21 18:37, Marc Zyngier wrote: > Direct mappings are completely exclusive of normal mappings, meaning > that we can refactor the code slightly so that we can get rid of > the revmap_direct_max_irq field and use the revmap_size field > instead, reducing the size of the irqdomain structure. > > Signed-off-by: Marc Zyngier <maz@kernel.org>
This patch is breaking the POWER9/POWER10 XIVE driver (these are not old PPC systems :) on machines sharing the same LSI HW IRQ. For instance, a linux KVM guest with a virtio-rng and a virtio-balloon device. In that case, Linux creates two distinct IRQ mappings which can lead to some unexpected behavior.
A fix to go forward would be to change the XIVE IRQ domain to use a 'Tree' domain for reverse mapping and not the 'No Map' domain mapping. I will keep you updated for XIVE.
Thanks,
C.
> --- > include/linux/irqdomain.h | 6 +++--- > kernel/irq/irqdomain.c | 45 ++++++++++++++++++++++++++++++--------- > 2 files changed, 38 insertions(+), 13 deletions(-) > > diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h > index 723495ec5a2f..0916cf9c6e20 100644 > --- a/include/linux/irqdomain.h > +++ b/include/linux/irqdomain.h > @@ -149,8 +149,6 @@ struct irq_domain_chip_generic; > * @parent: Pointer to parent irq_domain to support hierarchy irq_domains > * > * Revmap data, used internally by irq_domain > - * @revmap_direct_max_irq: The largest hwirq that can be set for controllers that > - * support direct mapping > * @revmap_size: Size of the linear map table @revmap[] > * @revmap_tree: Radix map tree for hwirqs that don't fit in the linear map > * @revmap: Linear table of hwirq->virq reverse mappings > @@ -173,7 +171,6 @@ struct irq_domain { > > /* reverse map data. The linear map gets appended to the irq_domain */ > irq_hw_number_t hwirq_max; > - unsigned int revmap_direct_max_irq; > unsigned int revmap_size; > struct radix_tree_root revmap_tree; > struct mutex revmap_tree_mutex; > @@ -207,6 +204,9 @@ enum { > */ > IRQ_DOMAIN_MSI_NOMASK_QUIRK = (1 << 6), > > + /* Irq domain doesn't translate anything */ > + IRQ_DOMAIN_FLAG_NO_MAP = (1 << 7), > + > /* > * Flags starting from IRQ_DOMAIN_FLAG_NONCORE are reserved > * for implementation specific purposes and ignored by the > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > index e0143e640683..fa94c86e47d4 100644 > --- a/kernel/irq/irqdomain.c > +++ b/kernel/irq/irqdomain.c > @@ -146,6 +146,10 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size, > > static atomic_t unknown_domains; > > + if (WARN_ON((size && direct_max) || > + (!IS_ENABLED(CONFIG_IRQ_DOMAIN_NOMAP) && direct_max))) > + return NULL; > + > domain = kzalloc_node(sizeof(*domain) + (sizeof(unsigned int) * size), > GFP_KERNEL, of_node_to_nid(to_of_node(fwnode))); > if (!domain) > @@ -213,8 +217,14 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size, > domain->ops = ops; > domain->host_data = host_data; > domain->hwirq_max = hwirq_max; > + > + if (direct_max) { > + size = direct_max; > + domain->flags |= IRQ_DOMAIN_FLAG_NO_MAP; > + } > + > domain->revmap_size = size; > - domain->revmap_direct_max_irq = direct_max; > + > irq_domain_check_hierarchy(domain); > > mutex_lock(&irq_domain_mutex); > @@ -482,9 +492,18 @@ struct irq_domain *irq_get_default_host(void) > return irq_default_domain; > } > > +static bool irq_domain_is_nomap(struct irq_domain *domain) > +{ > + return IS_ENABLED(CONFIG_IRQ_DOMAIN_NOMAP) && > + (domain->flags & IRQ_DOMAIN_FLAG_NO_MAP); > +} > + > static void irq_domain_clear_mapping(struct irq_domain *domain, > irq_hw_number_t hwirq) > { > + if (irq_domain_is_nomap(domain)) > + return; > + > if (hwirq < domain->revmap_size) { > domain->revmap[hwirq] = 0; > } else { > @@ -498,6 +517,9 @@ static void irq_domain_set_mapping(struct irq_domain *domain, > irq_hw_number_t hwirq, > struct irq_data *irq_data) > { > + if (irq_domain_is_nomap(domain)) > + return; > + > if (hwirq < domain->revmap_size) { > domain->revmap[hwirq] = irq_data->irq; > } else { > @@ -629,9 +651,9 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain) > pr_debug("create_direct virq allocation failed\n"); > return 0; > } > - if (virq >= domain->revmap_direct_max_irq) { > + if (virq >= domain->revmap_size) { > pr_err("ERROR: no free irqs available below %i maximum\n", > - domain->revmap_direct_max_irq); > + domain->revmap_size); > irq_free_desc(virq); > return 0; > } > @@ -879,10 +901,14 @@ unsigned int irq_find_mapping(struct irq_domain *domain, > if (domain == NULL) > return 0; > > - if (hwirq < domain->revmap_direct_max_irq) { > - data = irq_domain_get_irq_data(domain, hwirq); > - if (data && data->hwirq == hwirq) > - return hwirq; > + if (irq_domain_is_nomap(domain)) { > + if (hwirq < domain->revmap_size) { > + data = irq_domain_get_irq_data(domain, hwirq); > + if (data && data->hwirq == hwirq) > + return hwirq; > + } > + > + return 0; > } > > /* Check if the hwirq is in the linear revmap. */ > @@ -1470,7 +1496,7 @@ static void irq_domain_fix_revmap(struct irq_data *d) > { > void __rcu **slot; > > - if (d->hwirq < d->domain->revmap_size) > + if (irq_domain_is_nomap(d->domain) || d->hwirq < d->domain->revmap_size) > return; /* Not using radix tree. */ > > /* Fix up the revmap. */ > @@ -1830,8 +1856,7 @@ static void > irq_domain_debug_show_one(struct seq_file *m, struct irq_domain *d, int ind) > { > seq_printf(m, "%*sname: %s\n", ind, "", d->name); > - seq_printf(m, "%*ssize: %u\n", ind + 1, "", > - d->revmap_size + d->revmap_direct_max_irq); > + seq_printf(m, "%*ssize: %u\n", ind + 1, "", d->revmap_size); > seq_printf(m, "%*smapped: %u\n", ind + 1, "", d->mapcount); > seq_printf(m, "%*sflags: 0x%08x\n", ind +1 , "", d->flags); > if (d->ops && d->ops->debug_show) >
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