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

Shradha Gupta
2025-04-22T12:09:20Z

> On Wed, Apr 16, 2025 at 08:36:21AM -0700, Shradha Gupta wrote:
> > 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
>
> Can you replace the 'set of cpus' with a 'sibling group'?
>
> > + * to HWC IRQ
> > + */
>
> This comment should not be here. This is a helper function. User may want to skip
> 1st CPU for whatever reason. Please put the comment in
> mana_gd_setup_dyn_irqs().
>
> > + if (skip_cpu && !i) {
> > + i = 1;
> > + goto next_cpumask;
> > + }
>
> The 'skip_cpu' variable should be a boolean, and has more a specific name. And
> you don't need the local 'i' to implement your logic:
>
> if (unlikely(skip_first_cpu)) {
> skip_first_cpu = false;
> goto next_sibling;
> }
>
> > if (len-- == 0)
> > goto done;
>
> This check should go before the one you're adding here.

Hi Yury,
While preparing for the v2 for this patch, I realized that the movement of this 'if(len-- == 0)' check
above 'if(unlikely(skip_first_cpu))' is not needed as we are deliberately trying to skip 'len--'
in the iteration where skip_first_cpu is true.

Regards,
Shradha

>
> > +
> > 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