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

Yury Norov
2025-04-16T17:22:08Z

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.

> +
> 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