[PATCH 1/4] genirq/msi: Add .msi_teardown() callback as the reverse of .msi_prepare()

Marc Zyngier
2025-05-11T16:35:27Z

While the MSI ops do have a .msi_prepare() callback that is
responsible for setting up the relevant (usually per-device)
allocation, we don't have a callback reversing this setup.

For this purpose, let's a .msi_teardown() callback. This is
reliying on the msi_domain_info structure having a non-NULL
alloc_data field.

Nobody is populating this field yet, so there is no change
in behaviour yet.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
include/linux/msi.h | 10 ++++++++--
kernel/irq/msi.c | 12 ++++++++++++
2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 86e42742fd0fb..0a44a2cba3105 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -420,6 +420,7 @@ struct msi_domain_info;
* @msi_init: Domain specific init function for MSI interrupts
* @msi_free: Domain specific function to free a MSI interrupts
* @msi_prepare: Prepare the allocation of the interrupts in the domain
+ * @msi_teardown: Reverse the effects of @msi_prepare
* @prepare_desc: Optional function to prepare the allocated MSI descriptor
* in the domain
* @set_desc: Set the msi descriptor for an interrupt
@@ -435,8 +436,9 @@ struct msi_domain_info;
* @get_hwirq, @msi_init and @msi_free are callbacks used by the underlying
* irqdomain.
*
- * @msi_check, @msi_prepare, @prepare_desc and @set_desc are callbacks used by the
- * msi_domain_alloc/free_irqs*() variants.
+ * @msi_check, @msi_prepare, @msi_teardown, @prepare_desc and
+ * @set_desc are callbacks used by the msi_domain_alloc/free_irqs*()
+ * variants.
*
* @domain_alloc_irqs, @domain_free_irqs can be used to override the
* default allocation/free functions (__msi_domain_alloc/free_irqs). This
@@ -458,6 +460,8 @@ struct msi_domain_ops {
int (*msi_prepare)(struct irq_domain *domain,
struct device *dev, int nvec,
msi_alloc_info_t *arg);
+ void (*msi_teardown)(struct irq_domain *domain,
+ msi_alloc_info_t *arg);
void (*prepare_desc)(struct irq_domain *domain, msi_alloc_info_t *arg,
struct msi_desc *desc);
void (*set_desc)(msi_alloc_info_t *arg,
@@ -486,6 +490,7 @@ struct msi_domain_ops {
* @handler: Optional: associated interrupt flow handler
* @handler_data: Optional: associated interrupt flow handler data
* @handler_name: Optional: associated interrupt flow handler name
+ * @alloc_data: Optional: associated interrupt allocation data
* @data: Optional: domain specific data
*/
struct msi_domain_info {
@@ -498,6 +503,7 @@ struct msi_domain_info {
irq_flow_handler_t handler;
void *handler_data;
const char *handler_name;
+ msi_alloc_info_t *alloc_data;
void *data;
};

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index c05ba7ca00faa..a65ccf19b15d9 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -796,6 +796,11 @@ static int msi_domain_ops_prepare(struct irq_domain *domain, struct device *dev,
return 0;
}

+static void msi_domain_ops_teardown(struct irq_domain *domain,
+ msi_alloc_info_t *arg)
+{
+}
+
static void msi_domain_ops_set_desc(msi_alloc_info_t *arg,
struct msi_desc *desc)
{
@@ -821,6 +826,7 @@ static struct msi_domain_ops msi_domain_ops_default = {
.get_hwirq = msi_domain_ops_get_hwirq,
.msi_init = msi_domain_ops_init,
.msi_prepare = msi_domain_ops_prepare,
+ .msi_teardown = msi_domain_ops_teardown,
.set_desc = msi_domain_ops_set_desc,
};

@@ -842,6 +848,8 @@ static void msi_domain_update_dom_ops(struct msi_domain_info *info)
ops->msi_init = msi_domain_ops_default.msi_init;
if (ops->msi_prepare == NULL)
ops->msi_prepare = msi_domain_ops_default.msi_prepare;
+ if (ops->msi_teardown == NULL)
+ ops->msi_teardown = msi_domain_ops_default.msi_teardown;
if (ops->set_desc == NULL)
ops->set_desc = msi_domain_ops_default.set_desc;
}
@@ -1088,6 +1096,10 @@ void msi_remove_device_irq_domain(struct device *dev, unsigned int domid)

dev->msi.data->__domains[domid].domain = NULL;
info = domain->host_data;
+
+ if (info->alloc_data)
+ info->ops->msi_teardown(domain, info->alloc_data);
+
if (irq_domain_is_msi_device(domain))
fwnode = domain->fwnode;
irq_domain_remove(domain);
--
2.39.2