[PATCH 2/2] net: mana: Allow MANA driver to allocate PCI vector dynamically

Shradha Gupta
2025-04-16T15:36:22Z

Currently, the MANA driver allocates pci vector statically based on
MANA_MAX_NUM_QUEUES and num_online_cpus() values and in some cases ends
up allocating more vectors than it needs.
This is because, by this time we do not have a HW channel and do not know
how many IRQs should be allocated.
To avoid this, we allocate 1 IRQ vector during the creation of HWC and
after getting the value supported by hardware, dynamically add the
remaining vectors.

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
.../net/ethernet/microsoft/mana/gdma_main.c | 306 ++++++++++++++----
include/net/mana/gdma.h | 5 +-
2 files changed, 250 insertions(+), 61 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 4ffaf7588885..3e3b5854b736 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -6,6 +6,9 @@
#include <linux/pci.h>
#include <linux/utsname.h>
#include <linux/version.h>
+#include <linux/msi.h>
+#include <linux/irqdomain.h>
+#include <linux/list.h>

#include <net/mana/mana.h>

@@ -80,8 +83,15 @@ static int mana_gd_query_max_resources(struct pci_dev *pdev)
return err ? err : -EPROTO;
}

- if (gc->num_msix_usable > resp.max_msix)
- gc->num_msix_usable = resp.max_msix;
+ if (!pci_msix_can_alloc_dyn(pdev)) {
+ if (gc->num_msix_usable > resp.max_msix)
+ gc->num_msix_usable = resp.max_msix;
+ } else {
+ /* If dynamic allocation is enabled we have already allocated
+ * hwc msi
+ */
+ gc->num_msix_usable = min(resp.max_msix, num_online_cpus() + 1);
+ }

if (gc->num_msix_usable <= 1)
return -ENOSPC;
@@ -465,9 +475,10 @@ static int mana_gd_register_irq(struct gdma_queue *queue,
struct gdma_irq_context *gic;
struct gdma_context *gc;
unsigned int msi_index;
- unsigned long flags;
+ struct list_head *pos;
+ unsigned long flags, flag_irq;
struct device *dev;
- int err = 0;
+ int err = 0, count;

gc = gd->gdma_context;
dev = gc->dev;
@@ -482,7 +493,22 @@ static int mana_gd_register_irq(struct gdma_queue *queue,
}

queue->eq.msix_index = msi_index;
- gic = &gc->irq_contexts[msi_index];
+
+ /* get the msi_index value from the list*/
+ count = 0;
+ spin_lock_irqsave(&gc->irq_ctxs_lock, flag_irq);
+ list_for_each(pos, &gc->irq_contexts) {
+ if (count == msi_index) {
+ gic = list_entry(pos, struct gdma_irq_context, gic_list);
+ break;
+ }
+
+ count++;
+ }
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flag_irq);
+
+ if (!gic)
+ return -1;

spin_lock_irqsave(&gic->lock, flags);
list_add_rcu(&queue->entry, &gic->eq_list);
@@ -497,8 +523,10 @@ static void mana_gd_deregiser_irq(struct gdma_queue *queue)
struct gdma_irq_context *gic;
struct gdma_context *gc;
unsigned int msix_index;
- unsigned long flags;
+ struct list_head *pos;
+ unsigned long flags, flag_irq;
struct gdma_queue *eq;
+ int count;

gc = gd->gdma_context;

@@ -507,7 +535,22 @@ static void mana_gd_deregiser_irq(struct gdma_queue *queue)
if (WARN_ON(msix_index >= gc->num_msix_usable))
return;

- gic = &gc->irq_contexts[msix_index];
+ /* get the msi_index value from the list*/
+ count = 0;
+ spin_lock_irqsave(&gc->irq_ctxs_lock, flag_irq);
+ list_for_each(pos, &gc->irq_contexts) {
+ if (count == msix_index) {
+ gic = list_entry(pos, struct gdma_irq_context, gic_list);
+ break;
+ }
+
+ count++;
+ }
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flag_irq);
+
+ if (!gic)
+ return;
+
spin_lock_irqsave(&gic->lock, flags);
list_for_each_entry_rcu(eq, &gic->eq_list, entry) {
if (queue == eq) {
@@ -1288,11 +1331,11 @@ void mana_gd_free_res_map(struct gdma_resource *r)
r->size = 0;
}

-static int irq_setup(unsigned int *irqs, unsigned int len, int node)
+static int irq_setup(unsigned int *irqs, unsigned int len, int node, int skip_cpu)
{
const struct cpumask *next, *prev = cpu_none_mask;
cpumask_var_t cpus __free(free_cpumask_var);
- int cpu, weight;
+ int cpu, weight, i = 0;

if (!alloc_cpumask_var(&cpus, GFP_KERNEL))
return -ENOMEM;
@@ -1303,9 +1346,21 @@ static int irq_setup(unsigned int *irqs, unsigned int len, int node)
while (weight > 0) {
cpumask_andnot(cpus, next, prev);
for_each_cpu(cpu, cpus) {
+ /* If the call is made for irqs which are dynamically
+ * added and the num of vcpus is more or equal to
+ * allocated msix, we need to skip the first
+ * set of cpus, since they are already affinitized
+ * to HWC IRQ
+ */
+ if (skip_cpu && !i) {
+ i = 1;
+ goto next_cpumask;
+ }
if (len-- == 0)
goto done;
+
irq_set_affinity_and_hint(*irqs++, topology_sibling_cpumask(cpu));
+next_cpumask:
cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
--weight;
}
@@ -1317,29 +1372,92 @@ static int irq_setup(unsigned int *irqs, unsigned int len, int node)
return 0;
}

-static int mana_gd_setup_irqs(struct pci_dev *pdev)
+static int mana_gd_setup_dyn_irqs(struct pci_dev *pdev, int nvec)
{
struct gdma_context *gc = pci_get_drvdata(pdev);
- unsigned int max_queues_per_port;
struct gdma_irq_context *gic;
- unsigned int max_irqs, cpu;
- int start_irq_index = 1;
- int nvec, *irqs, irq;
+ int *irqs, irq, skip_first_cpu = 0;
+ unsigned long flags;
int err, i = 0, j;

cpus_read_lock();
- max_queues_per_port = num_online_cpus();
- if (max_queues_per_port > MANA_MAX_NUM_QUEUES)
- max_queues_per_port = MANA_MAX_NUM_QUEUES;
+ spin_lock_irqsave(&gc->irq_ctxs_lock, flags);
+ irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL);
+ if (!irqs) {
+ err = -ENOMEM;
+ goto free_irq_vector;
+ }

- /* Need 1 interrupt for the Hardware communication Channel (HWC) */
- max_irqs = max_queues_per_port + 1;
+ for (i = 0; i < nvec; i++) {
+ gic = kcalloc(1, sizeof(struct gdma_irq_context), GFP_KERNEL);
+ if (!gic) {
+ err = -ENOMEM;
+ goto free_irq;
+ }
+ gic->handler = mana_gd_process_eq_events;
+ INIT_LIST_HEAD(&gic->eq_list);
+ spin_lock_init(&gic->lock);

- nvec = pci_alloc_irq_vectors(pdev, 2, max_irqs, PCI_IRQ_MSIX);
- if (nvec < 0) {
- cpus_read_unlock();
- return nvec;
+ snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_q%d@pci:%s",
+ i, pci_name(pdev));
+
+ /* one pci vector is already allocated for HWC */
+ irqs[i] = pci_irq_vector(pdev, i + 1);
+ if (irqs[i] < 0) {
+ err = irqs[i];
+ goto free_current_gic;
+ }
+
+ err = request_irq(irqs[i], mana_gd_intr, 0, gic->name, gic);
+ if (err)
+ goto free_current_gic;
+
+ list_add_tail(&gic->gic_list, &gc->irq_contexts);
+ }
+
+ if (gc->num_msix_usable <= num_online_cpus())
+ skip_first_cpu = 1;
+
+ err = irq_setup(irqs, nvec, gc->numa_node, skip_first_cpu);
+ if (err)
+ goto free_irq;
+
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flags);
+ cpus_read_unlock();
+ kfree(irqs);
+ return 0;
+
+free_current_gic:
+ kfree(gic);
+free_irq:
+ for (j = i - 1; j >= 0; j--) {
+ irq = pci_irq_vector(pdev, j + 1);
+ gic = list_last_entry(&gc->irq_contexts, struct gdma_irq_context, gic_list);
+ irq_update_affinity_hint(irq, NULL);
+ free_irq(irq, gic);
+ list_del(&gic->gic_list);
+ kfree(gic);
}
+ kfree(irqs);
+free_irq_vector:
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flags);
+ cpus_read_unlock();
+ return err;
+}
+
+static int mana_gd_setup_irqs(struct pci_dev *pdev, int nvec)
+{
+ struct gdma_context *gc = pci_get_drvdata(pdev);
+ struct gdma_irq_context *gic;
+ int start_irq_index = 1;
+ unsigned long flags;
+ unsigned int cpu;
+ int *irqs, irq;
+ int err, i = 0, j;
+
+ cpus_read_lock();
+ spin_lock_irqsave(&gc->irq_ctxs_lock, flags);
+
if (nvec <= num_online_cpus())
start_irq_index = 0;

@@ -1349,15 +1467,12 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
goto free_irq_vector;
}

- gc->irq_contexts = kcalloc(nvec, sizeof(struct gdma_irq_context),
- GFP_KERNEL);
- if (!gc->irq_contexts) {
- err = -ENOMEM;
- goto free_irq_array;
- }
-
for (i = 0; i < nvec; i++) {
- gic = &gc->irq_contexts[i];
+ gic = kcalloc(1, sizeof(struct gdma_irq_context), GFP_KERNEL);
+ if (!gic) {
+ err = -ENOMEM;
+ goto free_irq;
+ }
gic->handler = mana_gd_process_eq_events;
INIT_LIST_HEAD(&gic->eq_list);
spin_lock_init(&gic->lock);
@@ -1372,22 +1487,14 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
irq = pci_irq_vector(pdev, i);
if (irq < 0) {
err = irq;
- goto free_irq;
+ goto free_current_gic;
}

if (!i) {
err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
if (err)
- goto free_irq;
-
- /* If number of IRQ is one extra than number of online CPUs,
- * then we need to assign IRQ0 (hwc irq) and IRQ1 to
- * same CPU.
- * Else we will use different CPUs for IRQ0 and IRQ1.
- * Also we are using cpumask_local_spread instead of
- * cpumask_first for the node, because the node can be
- * mem only.
- */
+ goto free_current_gic;
+
if (start_irq_index) {
cpu = cpumask_local_spread(i, gc->numa_node);
irq_set_affinity_and_hint(irq, cpumask_of(cpu));
@@ -1399,36 +1506,104 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
err = request_irq(irqs[i - start_irq_index], mana_gd_intr, 0,
gic->name, gic);
if (err)
- goto free_irq;
+ goto free_current_gic;
}
+
+ list_add_tail(&gic->gic_list, &gc->irq_contexts);
}

- err = irq_setup(irqs, (nvec - start_irq_index), gc->numa_node);
+ err = irq_setup(irqs, nvec - start_irq_index, gc->numa_node, 0);
if (err)
goto free_irq;

- gc->max_num_msix = nvec;
- gc->num_msix_usable = nvec;
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flags);
cpus_read_unlock();
kfree(irqs);
return 0;

+free_current_gic:
+ kfree(gic);
free_irq:
for (j = i - 1; j >= 0; j--) {
irq = pci_irq_vector(pdev, j);
- gic = &gc->irq_contexts[j];
-
+ gic = list_last_entry(&gc->irq_contexts, struct gdma_irq_context, gic_list);
irq_update_affinity_hint(irq, NULL);
free_irq(irq, gic);
+ list_del(&gic->gic_list);
+ kfree(gic);
}
-
- kfree(gc->irq_contexts);
- gc->irq_contexts = NULL;
-free_irq_array:
kfree(irqs);
free_irq_vector:
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flags);
cpus_read_unlock();
- pci_free_irq_vectors(pdev);
+ return err;
+}
+
+static int mana_gd_setup_hwc_irqs(struct pci_dev *pdev)
+{
+ struct gdma_context *gc = pci_get_drvdata(pdev);
+ unsigned int max_irqs, min_irqs;
+ int max_queues_per_port;
+ int nvec, err;
+
+ if (pci_msix_can_alloc_dyn(pdev)) {
+ max_irqs = 1;
+ min_irqs = 1;
+ } else {
+ max_queues_per_port = num_online_cpus();
+ if (max_queues_per_port > MANA_MAX_NUM_QUEUES)
+ max_queues_per_port = MANA_MAX_NUM_QUEUES;
+ /* Need 1 interrupt for the Hardware communication Channel (HWC) */
+ max_irqs = max_queues_per_port + 1;
+ min_irqs = 2;
+ }
+
+ nvec = pci_alloc_irq_vectors(pdev, min_irqs, max_irqs, PCI_IRQ_MSIX);
+ if (nvec < 0)
+ return nvec;
+
+ err = mana_gd_setup_irqs(pdev, nvec);
+ if (err) {
+ pci_free_irq_vectors(pdev);
+ return err;
+ }
+
+ gc->num_msix_usable = nvec;
+ gc->max_num_msix = nvec;
+
+ return err;
+}
+
+static int mana_gd_setup_remaining_irqs(struct pci_dev *pdev)
+{
+ struct gdma_context *gc = pci_get_drvdata(pdev);
+ int max_irqs, i, err = 0;
+ struct msi_map irq_map;
+
+ if (!pci_msix_can_alloc_dyn(pdev))
+ /* remain irqs are already allocated with HWC IRQ */
+ return 0;
+
+ /* allocate only remaining IRQs*/
+ max_irqs = gc->num_msix_usable - 1;
+
+ for (i = 1; i <= max_irqs; i++) {
+ irq_map = pci_msix_alloc_irq_at(pdev, i, NULL);
+ if (!irq_map.virq) {
+ err = irq_map.index;
+ /* caller will handle cleaning up all allocated
+ * irqs, after HWC is destroyed
+ */
+ return err;
+ }
+ }
+
+ err = mana_gd_setup_dyn_irqs(pdev, max_irqs);
+ if (err)
+ return err;
+
+ gc->max_num_msix = gc->max_num_msix + max_irqs;
+
return err;
}

@@ -1436,29 +1611,34 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
{
struct gdma_context *gc = pci_get_drvdata(pdev);
struct gdma_irq_context *gic;
- int irq, i;
+ struct list_head *pos, *n;
+ unsigned long flags;
+ int irq, i = 0;

if (gc->max_num_msix < 1)
return;

- for (i = 0; i < gc->max_num_msix; i++) {
+ spin_lock_irqsave(&gc->irq_ctxs_lock, flags);
+ list_for_each_safe(pos, n, &gc->irq_contexts) {
irq = pci_irq_vector(pdev, i);
if (irq < 0)
continue;

- gic = &gc->irq_contexts[i];
+ gic = list_entry(pos, struct gdma_irq_context, gic_list);

/* Need to clear the hint before free_irq */
irq_update_affinity_hint(irq, NULL);
free_irq(irq, gic);
+ list_del(pos);
+ kfree(gic);
+ i++;
}
+ spin_unlock_irqrestore(&gc->irq_ctxs_lock, flags);

pci_free_irq_vectors(pdev);

gc->max_num_msix = 0;
gc->num_msix_usable = 0;
- kfree(gc->irq_contexts);
- gc->irq_contexts = NULL;
}

static int mana_gd_setup(struct pci_dev *pdev)
@@ -1469,9 +1649,9 @@ static int mana_gd_setup(struct pci_dev *pdev)
mana_gd_init_registers(pdev);
mana_smc_init(&gc->shm_channel, gc->dev, gc->shm_base);

- err = mana_gd_setup_irqs(pdev);
+ err = mana_gd_setup_hwc_irqs(pdev);
if (err) {
- dev_err(gc->dev, "Failed to setup IRQs: %d\n", err);
+ dev_err(gc->dev, "Failed to setup IRQs for HWC creation: %d\n", err);
return err;
}

@@ -1487,6 +1667,10 @@ static int mana_gd_setup(struct pci_dev *pdev)
if (err)
goto destroy_hwc;

+ err = mana_gd_setup_remaining_irqs(pdev);
+ if (err)
+ goto destroy_hwc;
+
err = mana_gd_detect_devices(pdev);
if (err)
goto destroy_hwc;
@@ -1563,6 +1747,8 @@ static int mana_gd_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
gc->is_pf = mana_is_pf(pdev->device);
gc->bar0_va = bar0_va;
gc->dev = &pdev->dev;
+ INIT_LIST_HEAD(&gc->irq_contexts);
+ spin_lock_init(&gc->irq_ctxs_lock);

if (gc->is_pf)
gc->mana_pci_debugfs = debugfs_create_dir("0", mana_debugfs_root);
diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
index 228603bf03f2..eae38d7302fe 100644
--- a/include/net/mana/gdma.h
+++ b/include/net/mana/gdma.h
@@ -363,6 +363,7 @@ struct gdma_irq_context {
spinlock_t lock;
struct list_head eq_list;
char name[MANA_IRQ_NAME_SZ];
+ struct list_head gic_list;
};

struct gdma_context {
@@ -373,7 +374,9 @@ struct gdma_context {
unsigned int max_num_queues;
unsigned int max_num_msix;
unsigned int num_msix_usable;
- struct gdma_irq_context *irq_contexts;
+ struct list_head irq_contexts;
+ /* Protect the irq_contexts list */
+ spinlock_t irq_ctxs_lock;

/* L2 MTU */
u16 adapter_mtu;
--
2.34.1