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    Subject[RFC PATCH v2 6/6] vfio: Add nested IOPF support
    Date
    To set up nested mode, drivers such as vfio_pci have to register
    a handler to receive stage/level 1 faults from the IOMMU, but
    since currently each device can only have one iommu dev fault
    handler, and if stage 2 IOPF is already enabled (VFIO_IOMMU_ENABLE_IOPF),
    we choose to update the registered handler (a combined one) via
    flags (set IOPF_REPORT_NESTED_L1_CONCERNED), and further deliver
    the received stage 1 faults in the handler to the guest through
    a newly added vfio_device_ops callback.

    Signed-off-by: Shenming Lu <lushenming@huawei.com>
    ---
    drivers/vfio/vfio.c | 83 +++++++++++++++++++++++++++++++++
    drivers/vfio/vfio_iommu_type1.c | 37 +++++++++++++++
    include/linux/vfio.h | 9 ++++
    3 files changed, 129 insertions(+)

    diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
    index 77b29bbd3027..c6a01d947d0d 100644
    --- a/drivers/vfio/vfio.c
    +++ b/drivers/vfio/vfio.c
    @@ -2389,6 +2389,89 @@ int vfio_iommu_dev_fault_handler(struct iommu_fault *fault, void *data)
    }
    EXPORT_SYMBOL_GPL(vfio_iommu_dev_fault_handler);

    +int vfio_iommu_dev_fault_handler_unregister_nested(struct device *dev)
    +{
    + struct vfio_container *container;
    + struct vfio_group *group;
    + struct vfio_iommu_driver *driver;
    + int ret;
    +
    + if (!dev)
    + return -EINVAL;
    +
    + group = vfio_group_get_from_dev(dev);
    + if (!group)
    + return -ENODEV;
    +
    + ret = vfio_group_add_container_user(group);
    + if (ret)
    + goto out;
    +
    + container = group->container;
    + driver = container->iommu_driver;
    + if (likely(driver && driver->ops->unregister_hdlr_nested))
    + ret = driver->ops->unregister_hdlr_nested(container->iommu_data,
    + dev);
    + else
    + ret = -ENOTTY;
    +
    + vfio_group_try_dissolve_container(group);
    +
    +out:
    + vfio_group_put(group);
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(vfio_iommu_dev_fault_handler_unregister_nested);
    +
    +/*
    + * Register/Update the VFIO page fault handler
    + * to receive nested stage/level 1 faults.
    + */
    +int vfio_iommu_dev_fault_handler_register_nested(struct device *dev)
    +{
    + struct vfio_container *container;
    + struct vfio_group *group;
    + struct vfio_iommu_driver *driver;
    + int ret;
    +
    + if (!dev)
    + return -EINVAL;
    +
    + group = vfio_group_get_from_dev(dev);
    + if (!group)
    + return -ENODEV;
    +
    + ret = vfio_group_add_container_user(group);
    + if (ret)
    + goto out;
    +
    + container = group->container;
    + driver = container->iommu_driver;
    + if (likely(driver && driver->ops->register_hdlr_nested))
    + ret = driver->ops->register_hdlr_nested(container->iommu_data,
    + dev);
    + else
    + ret = -ENOTTY;
    +
    + vfio_group_try_dissolve_container(group);
    +
    +out:
    + vfio_group_put(group);
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(vfio_iommu_dev_fault_handler_register_nested);
    +
    +int vfio_transfer_dev_fault(struct device *dev, struct iommu_fault *fault)
    +{
    + struct vfio_device *device = dev_get_drvdata(dev);
    +
    + if (unlikely(!device->ops->transfer))
    + return -EOPNOTSUPP;
    +
    + return device->ops->transfer(device->device_data, fault);
    +}
    +EXPORT_SYMBOL_GPL(vfio_transfer_dev_fault);
    +
    /**
    * Module/class support
    */
    diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
    index 8d14ced649a6..62ad4a47de4a 100644
    --- a/drivers/vfio/vfio_iommu_type1.c
    +++ b/drivers/vfio/vfio_iommu_type1.c
    @@ -3581,6 +3581,13 @@ static int vfio_iommu_type1_dma_map_iopf(void *iommu_data,
    enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
    struct iommu_page_response resp = {0};

    + /*
    + * When configured in nested mode, further deliver
    + * stage/level 1 faults to the guest.
    + */
    + if (iommu->nesting && !(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_L2))
    + return vfio_transfer_dev_fault(dev, fault);
    +
    mutex_lock(&iommu->lock);

    dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
    @@ -3654,6 +3661,34 @@ static int vfio_iommu_type1_dma_map_iopf(void *iommu_data,
    return 0;
    }

    +static int vfio_iommu_type1_register_hdlr_nested(void *iommu_data,
    + struct device *dev)
    +{
    + struct vfio_iommu *iommu = iommu_data;
    +
    + if (iommu->iopf_enabled)
    + return iommu_update_device_fault_handler(dev, ~0,
    + IOPF_REPORT_NESTED_L1_CONCERNED);
    + else
    + return iommu_register_device_fault_handler(dev,
    + vfio_iommu_dev_fault_handler,
    + IOPF_REPORT_NESTED |
    + IOPF_REPORT_NESTED_L1_CONCERNED,
    + dev);
    +}
    +
    +static int vfio_iommu_type1_unregister_hdlr_nested(void *iommu_data,
    + struct device *dev)
    +{
    + struct vfio_iommu *iommu = iommu_data;
    +
    + if (iommu->iopf_enabled)
    + return iommu_update_device_fault_handler(dev,
    + ~IOPF_REPORT_NESTED_L1_CONCERNED, 0);
    + else
    + return iommu_unregister_device_fault_handler(dev);
    +}
    +
    static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
    .name = "vfio-iommu-type1",
    .owner = THIS_MODULE,
    @@ -3670,6 +3705,8 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
    .group_iommu_domain = vfio_iommu_type1_group_iommu_domain,
    .notify = vfio_iommu_type1_notify,
    .dma_map_iopf = vfio_iommu_type1_dma_map_iopf,
    + .register_hdlr_nested = vfio_iommu_type1_register_hdlr_nested,
    + .unregister_hdlr_nested = vfio_iommu_type1_unregister_hdlr_nested,
    };

    static int __init vfio_iommu_type1_init(void)
    diff --git a/include/linux/vfio.h b/include/linux/vfio.h
    index 73af317a4343..60e935e4851b 100644
    --- a/include/linux/vfio.h
    +++ b/include/linux/vfio.h
    @@ -29,6 +29,7 @@
    * @match: Optional device name match callback (return: 0 for no-match, >0 for
    * match, -errno for abort (ex. match with insufficient or incorrect
    * additional args)
    + * @transfer: Optional. Transfer the received faults to the guest for nested mode.
    */
    struct vfio_device_ops {
    char *name;
    @@ -43,6 +44,7 @@ struct vfio_device_ops {
    int (*mmap)(void *device_data, struct vm_area_struct *vma);
    void (*request)(void *device_data, unsigned int count);
    int (*match)(void *device_data, char *buf);
    + int (*transfer)(void *device_data, struct iommu_fault *fault);
    };

    extern struct iommu_group *vfio_iommu_group_get(struct device *dev);
    @@ -102,6 +104,10 @@ struct vfio_iommu_driver_ops {
    int (*dma_map_iopf)(void *iommu_data,
    struct iommu_fault *fault,
    struct device *dev);
    + int (*register_hdlr_nested)(void *iommu_data,
    + struct device *dev);
    + int (*unregister_hdlr_nested)(void *iommu_data,
    + struct device *dev);
    };

    extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
    @@ -164,6 +170,9 @@ struct kvm;
    extern void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm);

    extern int vfio_iommu_dev_fault_handler(struct iommu_fault *fault, void *data);
    +extern int vfio_iommu_dev_fault_handler_unregister_nested(struct device *dev);
    +extern int vfio_iommu_dev_fault_handler_register_nested(struct device *dev);
    +extern int vfio_transfer_dev_fault(struct device *dev, struct iommu_fault *fault);

    /*
    * Sub-module helpers
    --
    2.19.1
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      Last update: 2021-03-09 07:23    [W:6.351 / U:0.036 seconds]
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