[PATCH v4 2/2] PCI: hv: Refactor hv_irq_unmask() to use cpumask_to_vpset()

[Maya Nakamura]

Remove the duplicate implementation of cpumask_to_vpset() and use the
shared implementation. Export hv_max_vp_index, which is required by
cpumask_to_vpset().

Apply changes to hv_irq_unmask() based on feedback.

Based on Vitaly's finding, use GFP_ATOMIC instead of GFP_KERNEL for
alloc_cpumask_var() because hv_irq_unmask() runs while a spinlock is
held.

Signed-off-by: Maya Nakamura <m.maya.nakamura@xxxxxxxxx>
---
Changes in v4:
 - Replace GFP_KERNEL with GFP_ATOMIC for alloc_cpumask_var().
 - Update the commit message.

Changes in v3:
 - Modify to catch all failures from cpumask_to_vpset().
 - Correct the v2 change log about the commit message.

Changes in v2:
 - Remove unnecessary nr_bank initialization.
 - Delete two unnecessary dev_err()'s.
 - Unlock before returning.
 - Update the commit message.

 arch/x86/hyperv/hv_init.c           |  1 +
 drivers/pci/controller/pci-hyperv.c | 38 +++++++++++++----------------
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 7abb09e2eeb8..7f2eed1fc81b 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -96,6 +96,7 @@ void  __percpu **hyperv_pcpu_input_arg;
 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
 
 u32 hv_max_vp_index;
+EXPORT_SYMBOL_GPL(hv_max_vp_index);
 
 static int hv_cpu_init(unsigned int cpu)
 {
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index d71695db1ba0..95441a35eceb 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -391,8 +391,6 @@ struct hv_interrupt_entry {
 	u32	data;
 };
 
-#define HV_VP_SET_BANK_COUNT_MAX	5 /* current implementation limit */
-
 /*
  * flags for hv_device_interrupt_target.flags
  */
@@ -908,12 +906,12 @@ static void hv_irq_unmask(struct irq_data *data)
 	struct retarget_msi_interrupt *params;
 	struct hv_pcibus_device *hbus;
 	struct cpumask *dest;
+	cpumask_var_t tmp;
 	struct pci_bus *pbus;
 	struct pci_dev *pdev;
 	unsigned long flags;
 	u32 var_size = 0;
-	int cpu_vmbus;
-	int cpu;
+	int cpu, nr_bank;
 	u64 res;
 
 	dest = irq_data_get_effective_affinity_mask(data);
@@ -953,29 +951,27 @@ static void hv_irq_unmask(struct irq_data *data)
 		 */
 		params->int_target.flags |=
 			HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;
-		params->int_target.vp_set.valid_bank_mask =
-			(1ull << HV_VP_SET_BANK_COUNT_MAX) - 1;
+
+		if (!alloc_cpumask_var(&tmp, GFP_ATOMIC)) {
+			res = 1;
+			goto exit_unlock;
+		}
+
+		cpumask_and(tmp, dest, cpu_online_mask);
+		nr_bank = cpumask_to_vpset(&params->int_target.vp_set, tmp);
+		free_cpumask_var(tmp);
+
+		if (nr_bank <= 0) {
+			res = 1;
+			goto exit_unlock;
+		}
 
 		/*
 		 * var-sized hypercall, var-size starts after vp_mask (thus
 		 * vp_set.format does not count, but vp_set.valid_bank_mask
 		 * does).
 		 */
-		var_size = 1 + HV_VP_SET_BANK_COUNT_MAX;
-
-		for_each_cpu_and(cpu, dest, cpu_online_mask) {
-			cpu_vmbus = hv_cpu_number_to_vp_number(cpu);
-
-			if (cpu_vmbus >= HV_VP_SET_BANK_COUNT_MAX * 64) {
-				dev_err(&hbus->hdev->device,
-					"too high CPU %d", cpu_vmbus);
-				res = 1;
-				goto exit_unlock;
-			}
-
-			params->int_target.vp_set.bank_contents[cpu_vmbus / 64]	|=
-				(1ULL << (cpu_vmbus & 63));
-		}
+		var_size = 1 + nr_bank;
 	} else {
 		for_each_cpu_and(cpu, dest, cpu_online_mask) {
 			params->int_target.vp_mask |=
-- 
2.17.1