PCI: hv: Allocate physically contiguous hypercall params buffer

hv_do_hypercall() assumes that we pass a segment from a physically
contiguous buffer.  A buffer allocated on the stack may not work if
CONFIG_VMAP_STACK=y is set.

Use kmalloc() to allocate this buffer.
Reported-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>

drivers/pci/host/pci-hyperv.c

@@ -378,6 +378,8 @@ struct hv_pcibus_device {
 	struct msi_domain_info msi_info;
 	struct msi_controller msi_chip;
 	struct irq_domain *irq_domain;
+	struct retarget_msi_interrupt retarget_msi_interrupt_params;
+	spinlock_t retarget_msi_interrupt_lock;
 };
 
 /*
@@ -774,34 +776,40 @@ static void hv_irq_unmask(struct irq_data *data)
 {
 	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
 	struct irq_cfg *cfg = irqd_cfg(data);
-	struct retarget_msi_interrupt params;
+	struct retarget_msi_interrupt *params;
 	struct hv_pcibus_device *hbus;
 	struct cpumask *dest;
 	struct pci_bus *pbus;
 	struct pci_dev *pdev;
 	int cpu;
+	unsigned long flags;
 
 	dest = irq_data_get_affinity_mask(data);
 	pdev = msi_desc_to_pci_dev(msi_desc);
 	pbus = pdev->bus;
 	hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
 
-	memset(&params, 0, sizeof(params));
-	params.partition_id = HV_PARTITION_ID_SELF;
-	params.source = 1; /* MSI(-X) */
-	params.address = msi_desc->msg.address_lo;
-	params.data = msi_desc->msg.data;
-	params.device_id = (hbus->hdev->dev_instance.b[5] << 24) |
+	spin_lock_irqsave(&hbus->retarget_msi_interrupt_lock, flags);
+
+	params = &hbus->retarget_msi_interrupt_params;
+	memset(params, 0, sizeof(*params));
+	params->partition_id = HV_PARTITION_ID_SELF;
+	params->source = 1; /* MSI(-X) */
+	params->address = msi_desc->msg.address_lo;
+	params->data = msi_desc->msg.data;
+	params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
 			   (hbus->hdev->dev_instance.b[4] << 16) |
 			   (hbus->hdev->dev_instance.b[7] << 8) |
 			   (hbus->hdev->dev_instance.b[6] & 0xf8) |
 			   PCI_FUNC(pdev->devfn);
-	params.vector = cfg->vector;
+	params->vector = cfg->vector;
 
 	for_each_cpu_and(cpu, dest, cpu_online_mask)
-		params.vp_mask |= (1ULL << vmbus_cpu_number_to_vp_number(cpu));
+		params->vp_mask |= (1ULL << vmbus_cpu_number_to_vp_number(cpu));
+
+	hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, params, NULL);
 
-	hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, &params, NULL);
+	spin_unlock_irqrestore(&hbus->retarget_msi_interrupt_lock, flags);
 
 	pci_msi_unmask_irq(data);
 }
@@ -2186,6 +2194,7 @@ static int hv_pci_probe(struct hv_device *hdev,
 	INIT_LIST_HEAD(&hbus->resources_for_children);
 	spin_lock_init(&hbus->config_lock);
 	spin_lock_init(&hbus->device_list_lock);
+	spin_lock_init(&hbus->retarget_msi_interrupt_lock);
 	sema_init(&hbus->enum_sem, 1);
 	init_completion(&hbus->remove_event);