[PATCH] pci-hyperv: use kmalloc to allocate hypercall params buffer

[Long Li]

From: Long Li <lon...@microsoft.com>

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

Change to use kmalloc to allocate this buffer.

The v2 patch adds locking to access the pre-allocated buffer.

Signed-off-by: Long Li <lon...@microsoft.com>
Reported-by: Haiyang Zhang <haiya...@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 763ff87..ca553df 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/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 @@ 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);
 
-- 
2.7.4