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

From: Bjorn Helgaas
Date: Wed Nov 23 2016 - 18:21:08 EST


On Tue, Nov 08, 2016 at 02:04:38PM -0800, Long Li wrote:
> From: Long Li <longli@xxxxxxxxxxxxx>
>
> 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 <longli@xxxxxxxxxxxxx>
> Reported-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>

Waiting for a maintainer ack for this.

$ ./scripts/get_maintainer.pl -f drivers/pci/host/pci-hyperv.c
"K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> (maintainer:Hyper-V CORE AND DRIVERS)
Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> (maintainer:Hyper-V CORE AND DRIVERS)
...

> ---
> 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
>
> --
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