Merge tag 'mlx5-updates-2023-03-20' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux

Saeed Mahameed says:

====================
mlx5-updates-2023-03-20

mlx5 dynamic msix

This patch series adds support for dynamic msix vectors allocation in mlx5.

Eli Cohen Says:

================

The following series of patches modifies mlx5_core to work with the
dynamic MSIX API. Currently, mlx5_core allocates all the interrupt
vectors it needs and distributes them amongst the consumers. With the
introduction of dynamic MSIX support, which allows for allocation of
interrupts more than once, we now allocate vectors as we need them.
This allows other drivers running on top of mlx5_core to allocate
interrupt vectors for their own use. An example for this is mlx5_vdpa,
which uses these vectors to propagate interrupts directly from the
hardware to the vCPU [1].

As a preparation for using this series, a use after free issue is fixed
in lib/cpu_rmap.c and the allocator for rmap entries has been modified.
A complementary API for irq_cpu_rmap_add() has also been introduced.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux.git/patch/?id=0f2bf1fcae96a83b8c5581854713c9fc3407556e

================

* tag 'mlx5-updates-2023-03-20' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux:
  net/mlx5: Provide external API for allocating vectors
  net/mlx5: Use one completion vector if eth is disabled
  net/mlx5: Refactor calculation of required completion vectors
  net/mlx5: Move devlink registration before mlx5_load
  net/mlx5: Use dynamic msix vectors allocation
  net/mlx5: Refactor completion irq request/release code
  net/mlx5: Improve naming of pci function vectors
  net/mlx5: Use newer affinity descriptor
  net/mlx5: Modify struct mlx5_irq to use struct msi_map
  net/mlx5: Fix wrong comment
  net/mlx5e: Coding style fix, add empty line
  lib: cpu_rmap: Add irq_cpu_rmap_remove to complement irq_cpu_rmap_add
  lib: cpu_rmap: Use allocator for rmap entries
  lib: cpu_rmap: Avoid use after free on rmap->obj array entries
====================

Link: https://lore.kernel.org/r/20230324231341.29808-1-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 46 insertions, 11 deletions

diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index f08d9c56f712..73c1636b927b 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -128,19 +128,31 @@ debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix)
 }
 #endif
 
+static int get_free_index(struct cpu_rmap *rmap)
+{
+	int i;
+
+	for (i = 0; i < rmap->size; i++)
+		if (!rmap->obj[i])
+			return i;
+
+	return -ENOSPC;
+}
+
 /**
  * cpu_rmap_add - add object to a rmap
  * @rmap: CPU rmap allocated with alloc_cpu_rmap()
  * @obj: Object to add to rmap
  *
- * Return index of object.
+ * Return index of object or -ENOSPC if no free entry was found
  */
 int cpu_rmap_add(struct cpu_rmap *rmap, void *obj)
 {
-	u16 index;
+	int index = get_free_index(rmap);
+
+	if (index < 0)
+		return index;
 
-	BUG_ON(rmap->used >= rmap->size);
-	index = rmap->used++;
 	rmap->obj[index] = obj;
 	return index;
 }
@@ -230,9 +242,10 @@ void free_irq_cpu_rmap(struct cpu_rmap *rmap)
 	if (!rmap)
 		return;
 
-	for (index = 0; index < rmap->used; index++) {
+	for (index = 0; index < rmap->size; index++) {
 		glue = rmap->obj[index];
-		irq_set_affinity_notifier(glue->notify.irq, NULL);
+		if (glue)
+			irq_set_affinity_notifier(glue->notify.irq, NULL);
 	}
 
 	cpu_rmap_put(rmap);
@@ -268,10 +281,22 @@ static void irq_cpu_rmap_release(struct kref *ref)
 		container_of(ref, struct irq_glue, notify.kref);
 
 	cpu_rmap_put(glue->rmap);
+	glue->rmap->obj[glue->index] = NULL;
 	kfree(glue);
 }
 
 /**
+ * irq_cpu_rmap_remove - remove an IRQ from a CPU affinity reverse-map
+ * @rmap: The reverse-map
+ * @irq: The IRQ number
+ */
+int irq_cpu_rmap_remove(struct cpu_rmap *rmap, int irq)
+{
+	return irq_set_affinity_notifier(irq, NULL);
+}
+EXPORT_SYMBOL(irq_cpu_rmap_remove);
+
+/**
  * irq_cpu_rmap_add - add an IRQ to a CPU affinity reverse-map
  * @rmap: The reverse-map
  * @irq: The IRQ number
@@ -293,12 +318,22 @@ int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
 	glue->notify.release = irq_cpu_rmap_release;
 	glue->rmap = rmap;
 	cpu_rmap_get(rmap);
-	glue->index = cpu_rmap_add(rmap, glue);
+	rc = cpu_rmap_add(rmap, glue);
+	if (rc < 0)
+		goto err_add;
+
+	glue->index = rc;
 	rc = irq_set_affinity_notifier(irq, &glue->notify);
-	if (rc) {
-		cpu_rmap_put(glue->rmap);
-		kfree(glue);
-	}
+	if (rc)
+		goto err_set;
+
+	return rc;
+
+err_set:
+	rmap->obj[glue->index] = NULL;
+err_add:
+	cpu_rmap_put(glue->rmap);
+	kfree(glue);
 	return rc;
 }
 EXPORT_SYMBOL(irq_cpu_rmap_add);