Re: [PATCH 16/39] irqdomain: Make normal and nomap irqdomains exclusive
From: Cédric Le Goater
Date: Mon Nov 15 2021 - 18:16:05 EST
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@xxxxxxxxxx>
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)