On Wed, May 28, 2025 at 01:16:38AM -0700, Saurabh Singh Sengar wrote:
> On Tue, May 27, 2025 at 08:59:03AM -0700, Shradha Gupta wrote:
> > Currently, the MANA driver allocates MSI-X vectors 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 MSI-X vector during the creation of HWC and
> > after getting the value supported by hardware, dynamically add the
> > remaining MSI-X vectors.
> >
> > Signed-off-by: Shradha Gupta <shradhagu...@linux.microsoft.com>
> > Reviewed-by: Haiyang Zhang <haiya...@microsoft.com>
> > ---
> > Changes in v4:
> > * added BUG_ON at appropriate places
> > * moved xa_destroy to mana_gd_remove()
> > * rearragned the cleanup logic in mana_gd_setup_dyn_irqs()
> > * simplified processing around start_irq_index in mana_gd_setup_irqs()
> > * return 0 instead of return err as appropriate
> > ---
> > Changes in v3:
> > * implemented irq_contexts as xarrays rather than list
> > * split the patch to create a perparation patch around irq_setup()
> > * add log when IRQ allocation/setup for remaining IRQs fails
> > ---
> > Changes in v2:
> > * Use string 'MSI-X vectors' instead of 'pci vectors'
> > * make skip-cpu a bool instead of int
> > * rearrange the comment arout skip_cpu variable appropriately
> > * update the capability bit for driver indicating dynamic IRQ allocation
> > * enforced max line length to 80
> > * enforced RCT convention
> > * initialized gic to NULL, for when there is a possibility of gic
> > not being populated correctly
> > ---
> > .../net/ethernet/microsoft/mana/gdma_main.c | 306 +++++++++++++-----
> > include/net/mana/gdma.h | 8 +-
> > 2 files changed, 235 insertions(+), 79 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > index 763a548c4a2b..98ebecbec9a7 100644
> > --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > @@ -6,6 +6,8 @@
> > #include <linux/pci.h>
> > #include <linux/utsname.h>
> > #include <linux/version.h>
> > +#include <linux/msi.h>
> > +#include <linux/irqdomain.h>
> >
> > #include <net/mana/mana.h>
> >
> > @@ -80,8 +82,15 @@ 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;
> > @@ -482,7 +491,9 @@ static int mana_gd_register_irq(struct gdma_queue
> > *queue,
> > }
> >
> > queue->eq.msix_index = msi_index;
> > - gic = &gc->irq_contexts[msi_index];
> > + gic = xa_load(&gc->irq_contexts, msi_index);
> > + if (WARN_ON(!gic))
> > + return -EINVAL;
> >
> > spin_lock_irqsave(&gic->lock, flags);
> > list_add_rcu(&queue->entry, &gic->eq_list);
> > @@ -507,7 +518,10 @@ 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];
> > + gic = xa_load(&gc->irq_contexts, msix_index);
> > + if (WARN_ON(!gic))
> > + return;
> > +
> > spin_lock_irqsave(&gic->lock, flags);
> > list_for_each_entry_rcu(eq, &gic->eq_list, entry) {
> > if (queue == eq) {
> > @@ -1366,47 +1380,113 @@ 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 err, i = 0, j;
> > + bool skip_first_cpu = false;
> > + int *irqs, irq, err, i;
> >
> > 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;
> >
> > - /* Need 1 interrupt for the Hardware communication Channel (HWC) */
> > - max_irqs = max_queues_per_port + 1;
> > -
> > - nvec = pci_alloc_irq_vectors(pdev, 2, max_irqs, PCI_IRQ_MSIX);
> > - if (nvec < 0) {
> > - cpus_read_unlock();
> > - return nvec;
> > - }
> > - if (nvec <= num_online_cpus())
> > - start_irq_index = 0;
> > -
> > - irqs = kmalloc_array((nvec - start_irq_index), sizeof(int), GFP_KERNEL);
> > + irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL);
> > if (!irqs) {
> > err = -ENOMEM;
> > goto free_irq_vector;
> > }
> >
> > - gc->irq_contexts = kcalloc(nvec, sizeof(struct gdma_irq_context),
> > - GFP_KERNEL);
> > - if (!gc->irq_contexts) {
> > + /*
> > + * While processing the next pci irq vector, we start with index 1,
> > + * as IRQ vector at index 0 is already processed for HWC.
> > + * However, the population of irqs array starts with index 0, to be
> > + * further used in irq_setup()
> > + */
> > + for (i = 1; i <= nvec; i++) {
> > + gic = kzalloc(sizeof(*gic), 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);
> > +
> > + snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_q%d@pci:%s",
> > + i - 1, pci_name(pdev));
> > +
> > + /* one pci vector is already allocated for HWC */
> > + irqs[i - 1] = pci_irq_vector(pdev, i);
> > + if (irqs[i - 1] < 0) {
> > + err = irqs[i - 1];
> > + goto free_current_gic;
> > + }
> > +
> > + err = request_irq(irqs[i - 1], mana_gd_intr, 0, gic->name, gic);
> > + if (err)
> > + goto free_current_gic;
> > +
> > + xa_store(&gc->irq_contexts, i, gic, GFP_KERNEL);
> > + }
> > +
> > + /*
> > + * When calling irq_setup() for dynamically added IRQs, if number of
> > + * CPUs is more than or equal to allocated MSI-X, we need to skip the
> > + * first CPU sibling group since they are already affinitized to HWC IRQ
> > + */
> > + if (gc->num_msix_usable <= num_online_cpus())
> > + skip_first_cpu = true;
> > +
> > + err = irq_setup(irqs, nvec, gc->numa_node, skip_first_cpu);
> > + if (err)
> > + goto free_irq;
> > +
> > + cpus_read_unlock();
> > + kfree(irqs);
> > + return 0;
> > +
> > +free_current_gic:
> > + kfree(gic);
> > +free_irq:
> > + for (i -= 1; i > 0; i--) {
> > + irq = pci_irq_vector(pdev, i);
> > + gic = xa_load(&gc->irq_contexts, i);
> > + if (WARN_ON(!gic))
> > + continue;
> > +
> > + irq_update_affinity_hint(irq, NULL);
> > + free_irq(irq, gic);
> > + xa_erase(&gc->irq_contexts, i);
> > + kfree(gic);
> > + }
> > + kfree(irqs);
> > +free_irq_vector:
> > + 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 *irqs, *start_irqs, irq;
> > + unsigned int cpu;
> > + int err, i;
> > +
> > + cpus_read_lock();
> > +
> > + irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL);
> > + if (!irqs) {
> > err = -ENOMEM;
> > - goto free_irq_array;
> > + goto free_irq_vector;
> > }
> >
> > for (i = 0; i < nvec; i++) {
> > - gic = &gc->irq_contexts[i];
> > + gic = kzalloc(sizeof(*gic), 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);
> > @@ -1418,69 +1498,128 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> > snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_q%d@pci:%s",
> > i - 1, pci_name(pdev));
> >
> > - irq = pci_irq_vector(pdev, i);
> > - if (irq < 0) {
> > - err = irq;
> > - goto free_irq;
> > + irqs[i] = pci_irq_vector(pdev, i);
> > + if (irqs[i] < 0) {
> > + err = irqs[i];
> > + 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.
> > - */
> > - if (start_irq_index) {
> > - cpu = cpumask_local_spread(i, gc->numa_node);
> > - irq_set_affinity_and_hint(irq, cpumask_of(cpu));
> > - } else {
> > - irqs[start_irq_index] = irq;
> > - }
> > - } else {
> > - irqs[i - start_irq_index] = irq;
> > - err = request_irq(irqs[i - start_irq_index],
> > mana_gd_intr, 0,
> > - gic->name, gic);
> > - if (err)
> > - goto free_irq;
> > - }
> > + err = request_irq(irqs[i], mana_gd_intr, 0, gic->name, gic);
> > + if (err)
> > + goto free_current_gic;
> > +
> > + xa_store(&gc->irq_contexts, i, gic, GFP_KERNEL);
> > }
> >
> > - err = irq_setup(irqs, nvec - start_irq_index, gc->numa_node, false);
> > + /* 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.
> > + */
> > + start_irqs = irqs;
> > + if (nvec > num_online_cpus()) {
> > + cpu = cpumask_local_spread(0, gc->numa_node);
> > + irq_set_affinity_and_hint(irqs[0], cpumask_of(cpu));
> > + irqs++;
> > + nvec -= 1;
> > + }
> > +
> > + err = irq_setup(irqs, nvec, gc->numa_node, false);
> > if (err)
> > goto free_irq;
> >
> > - gc->max_num_msix = nvec;
> > - gc->num_msix_usable = nvec;
> > cpus_read_unlock();
> > - kfree(irqs);
> > + kfree(start_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];
> > + for (i -= 1; i >= 0; i--) {
> > + irq = pci_irq_vector(pdev, i);
> > + gic = xa_load(&gc->irq_contexts, i);
> > + if (WARN_ON(!gic))
> > + continue;
> >
> > irq_update_affinity_hint(irq, NULL);
> > free_irq(irq, gic);
> > + xa_erase(&gc->irq_contexts, i);
> > + kfree(gic);
> > }
> >
> > - kfree(gc->irq_contexts);
> > - gc->irq_contexts = NULL;
> > -free_irq_array:
> > - kfree(irqs);
> > + kfree(start_irqs);
>
> There is a case when start_irqs can be used here uninitialized.
>
> - Saurabh
Thanks Saurabh. I'll get this in the next version
