[PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[Shradha Gupta]

In this patchset we want to enable the MANA driver to be able to
allocate MSI-X vectors in PCI dynamically.

The first patch exports pci_msix_prepare_desc() in PCI to be able to
correctly prepare descriptors for dynamically added MSI-X vectors.

The second patch adds the support of dynamic vector allocation in
pci-hyperv PCI controller by enabling the MSI_FLAG_PCI_MSIX_ALLOC_DYN
flag and using the pci_msix_prepare_desc() exported in first patch.

The third patch adds a detailed description of the irq_setup(), to
help understand the function design better.

The fourth patch is a preparation patch for mana changes to support
dynamic IRQ allocation. It contains changes in irq_setup() to allow
skipping first sibling CPU sets, in case certain IRQs are already
affinitized to them.

The fifth patch has the changes in MANA driver to be able to allocate
MSI-X vectors dynamically. If the support does not exist it defaults to
older behavior.

Since this patchset has patches from PCI and net tree, I am not entirely
sure what should be the target tree. Any suggestions/recommendations on
the same are welcomed.

---
Changes in v6
 * rebased to linux-next's v6.16-rc1 as per Jakub's suggestion
---
Changes in v5
 * Added Yury as Author of the 3rd patch
 * Fixed base commit information in the cover letter
 * Correctly initialized start_irqs, so that it is cleaned properly
 * rearranged the cpu_lock to minimize the critical section
---
 Change in v4
 * add a patch describing the functionality of irq_setup() through a 
   comment
 * In irq_setup(), avoid using a label next_cpumask:
 * modify the changes in MANA patch about restructuring the error
   handling path in mana_gd_setup_dyn_irqs()
 * modify the mana_gd_setup_irqs() to simplify handling around
   start_irq_index
 * add warning if an invalid gic is returned
 * place the xa_destroy() cleanup in mana_gd_remove
---
 Changes in v3
 * split the 3rd patch into preparation patch around irq_setup() and
   changes in mana driver to allow dynamic IRQ allocation
 * Add arm64 support for dynamic MSI-X allocation in pci_hyperv
   controller
---
 Changes in v2
 * split the first patch into two(exporting the preapre_desc
   func and using the function and flag in pci-hyperv)
 * replace 'pci vectors' by 'MSI-X vectors'
 * Change the cover letter description to align with changes made
---

Shradha Gupta (4):
  PCI/MSI: Export pci_msix_prepare_desc() for dynamic MSI-X allocations
  PCI: hv: Allow dynamic MSI-X vector allocation
  net: mana: Allow irq_setup() to skip cpus for affinity
  net: mana: Allocate MSI-X vectors dynamically

Yury Norov (1):
  net: mana: explain irq_setup() algorithm

 .../net/ethernet/microsoft/mana/gdma_main.c   | 366 ++++++++++++++----
 drivers/pci/controller/pci-hyperv.c           |   3 +-
 drivers/pci/msi/irqdomain.c                   |   5 +-
 include/linux/msi.h                           |   2 +
 include/net/mana/gdma.h                       |   8 +-
 5 files changed, 294 insertions(+), 90 deletions(-)


base-commit: 19a60293b9925080d97f22f122aca3fc46dadaf9
-- 
2.34.1

[PATCH v6 1/5] PCI/MSI: Export pci_msix_prepare_desc() for dynamic MSI-X allocations

[Shradha Gupta]

For supporting dynamic MSI-X vector allocation by PCI controllers, enabling
the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN is not enough, msix_prepare_msi_desc()
to prepare the MSI descriptor is also needed.

Export pci_msix_prepare_desc() to allow PCI controllers to support dynamic
MSI-X vector allocation.

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 drivers/pci/msi/irqdomain.c | 5 +++--
 include/linux/msi.h         | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index c05152733993..765312c92d9b 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -222,13 +222,14 @@ static void pci_irq_unmask_msix(struct irq_data *data)
 	pci_msix_unmask(irq_data_get_msi_desc(data));
 }
 
-static void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
-				  struct msi_desc *desc)
+void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
+			   struct msi_desc *desc)
 {
 	/* Don't fiddle with preallocated MSI descriptors */
 	if (!desc->pci.mask_base)
 		msix_prepare_msi_desc(to_pci_dev(desc->dev), desc);
 }
+EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
 
 static const struct msi_domain_template pci_msix_template = {
 	.chip = {
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 6863540f4b71..7f254bde5426 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -706,6 +706,8 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
 					     struct irq_domain *parent);
 u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
 struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
+void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
+			   struct msi_desc *desc);
 #else /* CONFIG_PCI_MSI */
 static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
 {
-- 
2.34.1

[PATCH v6 2/5] PCI: hv: Allow dynamic MSI-X vector allocation

[Shradha Gupta]

Allow dynamic MSI-X vector allocation for pci_hyperv PCI controller
by adding support for the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN and using
pci_msix_prepare_desc() to prepare the MSI-X descriptors.

Feature support added for both x86 and ARM64

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 Changes in v4:
 * use the same prepare_desc() callback for arm and x86
---
 Changes in v3:
 * Add arm64 support
---
 Changes in v2:
 * split the patch to keep changes in PCI and pci_hyperv controller
   seperate
 * replace strings "pci vectors" by "MSI-X vectors"
---
 drivers/pci/controller/pci-hyperv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index ef5d655a0052..86ca041bf74a 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -2119,6 +2119,7 @@ static struct irq_chip hv_msi_irq_chip = {
 static struct msi_domain_ops hv_msi_ops = {
 	.msi_prepare	= hv_msi_prepare,
 	.msi_free	= hv_msi_free,
+	.prepare_desc	= pci_msix_prepare_desc,
 };
 
 /**
@@ -2140,7 +2141,7 @@ static int hv_pcie_init_irq_domain(struct hv_pcibus_device *hbus)
 	hbus->msi_info.ops = &hv_msi_ops;
 	hbus->msi_info.flags = (MSI_FLAG_USE_DEF_DOM_OPS |
 		MSI_FLAG_USE_DEF_CHIP_OPS | MSI_FLAG_MULTI_PCI_MSI |
-		MSI_FLAG_PCI_MSIX);
+		MSI_FLAG_PCI_MSIX | MSI_FLAG_PCI_MSIX_ALLOC_DYN);
 	hbus->msi_info.handler = FLOW_HANDLER;
 	hbus->msi_info.handler_name = FLOW_NAME;
 	hbus->msi_info.data = hbus;
-- 
2.34.1

[PATCH v6 3/5] net: mana: explain irq_setup() algorithm

[Shradha Gupta]

From: Yury Norov <yury.norov@gmail.com>

Commit 91bfe210e196 ("net: mana: add a function to spread IRQs per CPUs")
added the irq_setup() function that distributes IRQs on CPUs according
to a tricky heuristic. The corresponding commit message explains the
heuristic.

Duplicate it in the source code to make available for readers without
digging git in history. Also, add more detailed explanation about how
the heuristics is implemented.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 Changes in v5:
 * Corrected the Authur of the patch
---
 .../net/ethernet/microsoft/mana/gdma_main.c   | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 3504507477c6..6c4e143972a1 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -1288,6 +1288,47 @@ void mana_gd_free_res_map(struct gdma_resource *r)
 	r->size = 0;
 }
 
+/*
+ * Spread on CPUs with the following heuristics:
+ *
+ * 1. No more than one IRQ per CPU, if possible;
+ * 2. NUMA locality is the second priority;
+ * 3. Sibling dislocality is the last priority.
+ *
+ * Let's consider this topology:
+ *
+ * Node            0               1
+ * Core        0       1       2       3
+ * CPU       0   1   2   3   4   5   6   7
+ *
+ * The most performant IRQ distribution based on the above topology
+ * and heuristics may look like this:
+ *
+ * IRQ     Nodes   Cores   CPUs
+ * 0       1       0       0-1
+ * 1       1       1       2-3
+ * 2       1       0       0-1
+ * 3       1       1       2-3
+ * 4       2       2       4-5
+ * 5       2       3       6-7
+ * 6       2       2       4-5
+ * 7       2       3       6-7
+ *
+ * The heuristics is implemented as follows.
+ *
+ * The outer for_each() loop resets the 'weight' to the actual number
+ * of CPUs in the hop. Then inner for_each() loop decrements it by the
+ * number of sibling groups (cores) while assigning first set of IRQs
+ * to each group. IRQs 0 and 1 above are distributed this way.
+ *
+ * Now, because NUMA locality is more important, we should walk the
+ * same set of siblings and assign 2nd set of IRQs (2 and 3), and it's
+ * implemented by the medium while() loop. We do like this unless the
+ * number of IRQs assigned on this hop will not become equal to number
+ * of CPUs in the hop (weight == 0). Then we switch to the next hop and
+ * do the same thing.
+ */
+
 static int irq_setup(unsigned int *irqs, unsigned int len, int node)
 {
 	const struct cpumask *next, *prev = cpu_none_mask;
-- 
2.34.1

[PATCH v6 4/5] net: mana: Allow irq_setup() to skip cpus for affinity

[Shradha Gupta]

In order to prepare the MANA driver to allocate the MSI-X IRQs
dynamically, we need to enhance irq_setup() to allow skipping
affinitizing IRQs to the first CPU sibling group.

This would be for cases when the number of IRQs is less than or equal
to the number of online CPUs. In such cases for dynamically added IRQs
the first CPU sibling group would already be affinitized with HWC IRQ.

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Yury Norov [NVIDIA] <yury.norov@gmail.com>
---
 Changes in v4
 * fix commit description
 * avoided using next_cpumask: label in the irq_setup()
---
 drivers/net/ethernet/microsoft/mana/gdma_main.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 6c4e143972a1..6e468c0f2c40 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -1329,7 +1329,8 @@ void mana_gd_free_res_map(struct gdma_resource *r)
  * do the same thing.
  */
 
-static int irq_setup(unsigned int *irqs, unsigned int len, int node)
+static int irq_setup(unsigned int *irqs, unsigned int len, int node,
+		     bool skip_first_cpu)
 {
 	const struct cpumask *next, *prev = cpu_none_mask;
 	cpumask_var_t cpus __free(free_cpumask_var);
@@ -1344,11 +1345,18 @@ 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) {
+				cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
+				--weight;
+
+				if (unlikely(skip_first_cpu)) {
+					skip_first_cpu = false;
+					continue;
+				}
+
 				if (len-- == 0)
 					goto done;
+
 				irq_set_affinity_and_hint(*irqs++, topology_sibling_cpumask(cpu));
-				cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
-				--weight;
 			}
 		}
 		prev = next;
@@ -1444,7 +1452,7 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
 		}
 	}
 
-	err = irq_setup(irqs, (nvec - start_irq_index), gc->numa_node);
+	err = irq_setup(irqs, nvec - start_irq_index, gc->numa_node, false);
 	if (err)
 		goto free_irq;
 
-- 
2.34.1

[PATCH v6 5/5] net: mana: Allocate MSI-X vectors dynamically

[Shradha Gupta]

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 <shradhagupta@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 Changes in v5:
 * Correctly initialized start_irqs, so that it is cleaned properly
 * rearranged the cpu_lock to minimize the critical section
---
 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   | 311 +++++++++++++-----
 include/net/mana/gdma.h                       |   8 +-
 2 files changed, 235 insertions(+), 84 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 6e468c0f2c40..d0040c12b8a2 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;
@@ -483,7 +492,9 @@ 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);
@@ -508,7 +519,10 @@ 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 +1380,108 @@ 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;
+	irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL);
+	if (!irqs)
+		return -ENOMEM;
+
+	/*
+	 * 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);
 
-	/* Need 1 interrupt for the Hardware communication Channel (HWC) */
-	max_irqs = max_queues_per_port + 1;
+		snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_q%d@pci:%s",
+			 i - 1, pci_name(pdev));
 
-	nvec = pci_alloc_irq_vectors(pdev, 2, max_irqs, PCI_IRQ_MSIX);
-	if (nvec < 0) {
-		cpus_read_unlock();
-		return nvec;
+		/* 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);
 	}
-	if (nvec <= num_online_cpus())
-		start_irq_index = 0;
 
-	irqs = kmalloc_array((nvec - start_irq_index), sizeof(int), GFP_KERNEL);
-	if (!irqs) {
-		err = -ENOMEM;
-		goto free_irq_vector;
+	/*
+	 * 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
+	 */
+	cpus_read_lock();
+	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) {
+		cpus_read_unlock();
+		goto free_irq;
 	}
 
-	gc->irq_contexts = kcalloc(nvec, sizeof(struct gdma_irq_context),
-				   GFP_KERNEL);
-	if (!gc->irq_contexts) {
-		err = -ENOMEM;
-		goto free_irq_array;
+	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);
+	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;
+
+	irqs = kmalloc_array(nvec, sizeof(int), GFP_KERNEL);
+	if (!irqs)
+		return -ENOMEM;
+
+	start_irqs = irqs;
 
 	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 +1493,128 @@ 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 (err)
+	/* 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.
+	 */
+	cpus_read_lock();
+	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) {
+		cpus_read_unlock();
 		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);
-free_irq_vector:
-	cpus_read_unlock();
-	pci_free_irq_vectors(pdev);
+	kfree(start_irqs);
 	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 nvec, err;
+
+	if (pci_msix_can_alloc_dyn(pdev)) {
+		max_irqs = 1;
+		min_irqs = 1;
+	} else {
+		/* Need 1 interrupt for HWC */
+		max_irqs = min(num_online_cpus(), MANA_MAX_NUM_QUEUES) + 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 0;
+}
+
+static int mana_gd_setup_remaining_irqs(struct pci_dev *pdev)
+{
+	struct gdma_context *gc = pci_get_drvdata(pdev);
+	struct msi_map irq_map;
+	int max_irqs, i, err;
+
+	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 0;
+}
+
 static void mana_gd_remove_irqs(struct pci_dev *pdev)
 {
 	struct gdma_context *gc = pci_get_drvdata(pdev);
@@ -1495,19 +1629,21 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
 		if (irq < 0)
 			continue;
 
-		gic = &gc->irq_contexts[i];
+		gic = xa_load(&gc->irq_contexts, i);
+		if (WARN_ON(!gic))
+			continue;
 
 		/* Need to clear the hint before free_irq */
 		irq_update_affinity_hint(irq, NULL);
 		free_irq(irq, gic);
+		xa_erase(&gc->irq_contexts, i);
+		kfree(gic);
 	}
 
 	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)
@@ -1522,9 +1658,10 @@ static int mana_gd_setup(struct pci_dev *pdev)
 	if (!gc->service_wq)
 		return -ENOMEM;
 
-	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);
 		goto free_workqueue;
 	}
 
@@ -1540,6 +1677,12 @@ static int mana_gd_setup(struct pci_dev *pdev)
 	if (err)
 		goto destroy_hwc;
 
+	err = mana_gd_setup_remaining_irqs(pdev);
+	if (err) {
+		dev_err(gc->dev, "Failed to setup remaining IRQs: %d", err);
+		goto destroy_hwc;
+	}
+
 	err = mana_gd_detect_devices(pdev);
 	if (err)
 		goto destroy_hwc;
@@ -1620,6 +1763,7 @@ 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;
+	xa_init(&gc->irq_contexts);
 
 	if (gc->is_pf)
 		gc->mana_pci_debugfs = debugfs_create_dir("0", mana_debugfs_root);
@@ -1654,6 +1798,7 @@ static int mana_gd_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	 */
 	debugfs_remove_recursive(gc->mana_pci_debugfs);
 	gc->mana_pci_debugfs = NULL;
+	xa_destroy(&gc->irq_contexts);
 	pci_iounmap(pdev, bar0_va);
 free_gc:
 	pci_set_drvdata(pdev, NULL);
@@ -1679,6 +1824,8 @@ static void mana_gd_remove(struct pci_dev *pdev)
 
 	gc->mana_pci_debugfs = NULL;
 
+	xa_destroy(&gc->irq_contexts);
+
 	pci_iounmap(pdev, gc->bar0_va);
 
 	vfree(gc);
diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
index 3ce56a816425..87162ba96d91 100644
--- a/include/net/mana/gdma.h
+++ b/include/net/mana/gdma.h
@@ -388,7 +388,7 @@ 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 xarray		irq_contexts;
 
 	/* L2 MTU */
 	u16 adapter_mtu;
@@ -578,12 +578,16 @@ enum {
 /* Driver can handle holes (zeros) in the device list */
 #define GDMA_DRV_CAP_FLAG_1_DEV_LIST_HOLES_SUP BIT(11)
 
+/* Driver supports dynamic MSI-X vector allocation */
+#define GDMA_DRV_CAP_FLAG_1_DYNAMIC_IRQ_ALLOC_SUPPORT BIT(13)
+
 #define GDMA_DRV_CAP_FLAGS1 \
 	(GDMA_DRV_CAP_FLAG_1_EQ_SHARING_MULTI_VPORT | \
 	 GDMA_DRV_CAP_FLAG_1_NAPI_WKDONE_FIX | \
 	 GDMA_DRV_CAP_FLAG_1_HWC_TIMEOUT_RECONFIG | \
 	 GDMA_DRV_CAP_FLAG_1_VARIABLE_INDIRECTION_TABLE_SUPPORT | \
-	 GDMA_DRV_CAP_FLAG_1_DEV_LIST_HOLES_SUP)
+	 GDMA_DRV_CAP_FLAG_1_DEV_LIST_HOLES_SUP | \
+	 GDMA_DRV_CAP_FLAG_1_DYNAMIC_IRQ_ALLOC_SUPPORT)
 
 #define GDMA_DRV_CAP_FLAGS2 0
 
-- 
2.34.1

Re: [PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[Jakub Kicinski]

On Wed, 11 Jun 2025 07:09:44 -0700 Shradha Gupta wrote:
> Changes in v6
>  * rebased to linux-next's v6.16-rc1 as per Jakub's suggestion

I meant a branch, basically apply the patches on the v6.16-rc1 tag
and push it out to GitHub, kernel.org or somewhere else public.
Then we can pull it in and maintain the stable commit IDs.
No need to repost the patches, FWIW, just share the branch here
once you pushed it out..

Re: [PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[Shradha Gupta]

On Wed, Jun 11, 2025 at 08:54:16AM -0700, Jakub Kicinski wrote:
> On Wed, 11 Jun 2025 07:09:44 -0700 Shradha Gupta wrote:
> > Changes in v6
> >  * rebased to linux-next's v6.16-rc1 as per Jakub's suggestion
> 
> I meant a branch, basically apply the patches on the v6.16-rc1 tag
> and push it out to GitHub, kernel.org or somewhere else public.
> Then we can pull it in and maintain the stable commit IDs.
> No need to repost the patches, FWIW, just share the branch here
> once you pushed it out..

Oh, understood. Thanks for the clarity. Here is a github repo branch
with the changes on v6.16-rc1 tag
https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc1

Would this suffice?

regards,
Shradha.

Re: [PATCH v6 1/5] PCI/MSI: Export pci_msix_prepare_desc() for dynamic MSI-X allocations

[Bjorn Helgaas]

On Wed, Jun 11, 2025 at 07:10:01AM -0700, Shradha Gupta wrote:
> For supporting dynamic MSI-X vector allocation by PCI controllers, enabling
> the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN is not enough, msix_prepare_msi_desc()
> to prepare the MSI descriptor is also needed.
> 
> Export pci_msix_prepare_desc() to allow PCI controllers to support dynamic
> MSI-X vector allocation.
> 
> Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
> Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
> Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>

If you need it; I see you already have a branch at
https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc1

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/msi/irqdomain.c | 5 +++--
>  include/linux/msi.h         | 2 ++
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
> index c05152733993..765312c92d9b 100644
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -222,13 +222,14 @@ static void pci_irq_unmask_msix(struct irq_data *data)
>  	pci_msix_unmask(irq_data_get_msi_desc(data));
>  }
>  
> -static void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
> -				  struct msi_desc *desc)
> +void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
> +			   struct msi_desc *desc)
>  {
>  	/* Don't fiddle with preallocated MSI descriptors */
>  	if (!desc->pci.mask_base)
>  		msix_prepare_msi_desc(to_pci_dev(desc->dev), desc);
>  }
> +EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
>  
>  static const struct msi_domain_template pci_msix_template = {
>  	.chip = {
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 6863540f4b71..7f254bde5426 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -706,6 +706,8 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
>  					     struct irq_domain *parent);
>  u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
>  struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
> +void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
> +			   struct msi_desc *desc);
>  #else /* CONFIG_PCI_MSI */
>  static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
>  {
> -- 
> 2.34.1
> 

Re: [PATCH v6 2/5] PCI: hv: Allow dynamic MSI-X vector allocation

[Bjorn Helgaas]

On Wed, Jun 11, 2025 at 07:10:15AM -0700, Shradha Gupta wrote:
> Allow dynamic MSI-X vector allocation for pci_hyperv PCI controller
> by adding support for the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN and using
> pci_msix_prepare_desc() to prepare the MSI-X descriptors.
> 
> Feature support added for both x86 and ARM64
> 
> Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
> Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>

Again, if you need it:

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  Changes in v4:
>  * use the same prepare_desc() callback for arm and x86
> ---
>  Changes in v3:
>  * Add arm64 support
> ---
>  Changes in v2:
>  * split the patch to keep changes in PCI and pci_hyperv controller
>    seperate
>  * replace strings "pci vectors" by "MSI-X vectors"
> ---
>  drivers/pci/controller/pci-hyperv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index ef5d655a0052..86ca041bf74a 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -2119,6 +2119,7 @@ static struct irq_chip hv_msi_irq_chip = {
>  static struct msi_domain_ops hv_msi_ops = {
>  	.msi_prepare	= hv_msi_prepare,
>  	.msi_free	= hv_msi_free,
> +	.prepare_desc	= pci_msix_prepare_desc,
>  };
>  
>  /**
> @@ -2140,7 +2141,7 @@ static int hv_pcie_init_irq_domain(struct hv_pcibus_device *hbus)
>  	hbus->msi_info.ops = &hv_msi_ops;
>  	hbus->msi_info.flags = (MSI_FLAG_USE_DEF_DOM_OPS |
>  		MSI_FLAG_USE_DEF_CHIP_OPS | MSI_FLAG_MULTI_PCI_MSI |
> -		MSI_FLAG_PCI_MSIX);
> +		MSI_FLAG_PCI_MSIX | MSI_FLAG_PCI_MSIX_ALLOC_DYN);
>  	hbus->msi_info.handler = FLOW_HANDLER;
>  	hbus->msi_info.handler_name = FLOW_NAME;
>  	hbus->msi_info.data = hbus;
> -- 
> 2.34.1
> 

Re: [PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[Jakub Kicinski]

On Wed, 11 Jun 2025 23:10:55 -0700 Shradha Gupta wrote:
> On Wed, Jun 11, 2025 at 08:54:16AM -0700, Jakub Kicinski wrote:
> > On Wed, 11 Jun 2025 07:09:44 -0700 Shradha Gupta wrote:  
> > > Changes in v6
> > >  * rebased to linux-next's v6.16-rc1 as per Jakub's suggestion  
> > 
> > I meant a branch, basically apply the patches on the v6.16-rc1 tag
> > and push it out to GitHub, kernel.org or somewhere else public.
> > Then we can pull it in and maintain the stable commit IDs.
> > No need to repost the patches, FWIW, just share the branch here
> > once you pushed it out..  
> 
> Oh, understood. Thanks for the clarity. Here is a github repo branch
> with the changes on v6.16-rc1 tag
> https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc1

The tag was good, but when I pulled it my check scripts complained:

Commit a19036b86845 ("net: mana: Allocate MSI-X vectors dynamically")
	committer Signed-off-by missing
	author email:    shradhagupta@linux.microsoft.com
	committer email: shradhagupta@microsoft.com
	Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>

etc. You seem to have committed the patches with a slightly different
email address. Not a huge deal but better to fix it if we can.

So please base the tag. The code can stay the same just adjust the
committer or author/signoff email addrs. We can use this as an
opportunity to add Bjorn's email.

No need to repost the code just ping here once you updated the tag.

Re: [PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[Shradha Gupta]

On Mon, Jun 16, 2025 at 06:11:48PM -0700, Jakub Kicinski wrote:
> On Wed, 11 Jun 2025 23:10:55 -0700 Shradha Gupta wrote:
> > On Wed, Jun 11, 2025 at 08:54:16AM -0700, Jakub Kicinski wrote:
> > > On Wed, 11 Jun 2025 07:09:44 -0700 Shradha Gupta wrote:  
> > > > Changes in v6
> > > >  * rebased to linux-next's v6.16-rc1 as per Jakub's suggestion  
> > > 
> > > I meant a branch, basically apply the patches on the v6.16-rc1 tag
> > > and push it out to GitHub, kernel.org or somewhere else public.
> > > Then we can pull it in and maintain the stable commit IDs.
> > > No need to repost the patches, FWIW, just share the branch here
> > > once you pushed it out..  
> > 
> > Oh, understood. Thanks for the clarity. Here is a github repo branch
> > with the changes on v6.16-rc1 tag
> > https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc1
> 
> The tag was good, but when I pulled it my check scripts complained:
> 
> Commit a19036b86845 ("net: mana: Allocate MSI-X vectors dynamically")
> 	committer Signed-off-by missing
> 	author email:    shradhagupta@linux.microsoft.com
> 	committer email: shradhagupta@microsoft.com
> 	Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
> 
> etc. You seem to have committed the patches with a slightly different
> email address. Not a huge deal but better to fix it if we can.
> 
> So please base the tag. The code can stay the same just adjust the
> committer or author/signoff email addrs. We can use this as an
> opportunity to add Bjorn's email.
> 
> No need to repost the code just ping here once you updated the tag.

Hi Jakub,

I have updated the tag with the corrected author and committer details
and added Bjorn's ack:
https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc1

By 'please base the tag', did you mean we rebase the changes with rc2?
If so, I have also created a rc2 tag branch, JFYI
https://github.com/shradhagupta6/linux/tree/shradha_v6.16-rc2

Hope this helps.

Thanks,
Shradha.

Re: [PATCH v6 0/5] Allow dyn MSI-X vector allocation of MANA

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Shradha Gupta <shradhagupta@linux.microsoft.com>:

On Wed, 11 Jun 2025 07:09:44 -0700 you wrote:
> In this patchset we want to enable the MANA driver to be able to
> allocate MSI-X vectors in PCI dynamically.
> 
> The first patch exports pci_msix_prepare_desc() in PCI to be able to
> correctly prepare descriptors for dynamically added MSI-X vectors.
> 
> The second patch adds the support of dynamic vector allocation in
> pci-hyperv PCI controller by enabling the MSI_FLAG_PCI_MSIX_ALLOC_DYN
> flag and using the pci_msix_prepare_desc() exported in first patch.
> 
> [...]

Here is the summary with links:
  - [v6,1/5] PCI/MSI: Export pci_msix_prepare_desc() for dynamic MSI-X allocations
    https://git.kernel.org/netdev/net-next/c/5da8a8b8090b
  - [v6,2/5] PCI: hv: Allow dynamic MSI-X vector allocation
    https://git.kernel.org/netdev/net-next/c/ad518f2557b9
  - [v6,3/5] net: mana: explain irq_setup() algorithm
    https://git.kernel.org/netdev/net-next/c/4607617af1b4
  - [v6,4/5] net: mana: Allow irq_setup() to skip cpus for affinity
    https://git.kernel.org/netdev/net-next/c/845c62c543d6
  - [v6,5/5] net: mana: Allocate MSI-X vectors dynamically
    https://git.kernel.org/netdev/net-next/c/755391121038

You are awesome, thank you!
-- 
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