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Date: Tue, 18 May 2021 12:58:08 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Shenming Lu <lushenming@...wei.com>
Cc: Cornelia Huck <cohuck@...hat.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Joerg Roedel <joro@...tes.org>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
Eric Auger <eric.auger@...hat.com>, <kvm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<iommu@...ts.linux-foundation.org>, <linux-api@...r.kernel.org>,
Kevin Tian <kevin.tian@...el.com>,
Lu Baolu <baolu.lu@...ux.intel.com>, <yi.l.liu@...el.com>,
Christoph Hellwig <hch@...radead.org>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Barry Song <song.bao.hua@...ilicon.com>,
<wanghaibin.wang@...wei.com>, <yuzenghui@...wei.com>
Subject: Re: [RFC PATCH v3 8/8] vfio: Add nested IOPF support
On Fri, 9 Apr 2021 11:44:20 +0800
Shenming Lu <lushenming@...wei.com> wrote:
> To set up nested mode, drivers such as vfio_pci need 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 consolidated one) via
> flags (set FAULT_REPORT_NESTED_L1), and further deliver the received
> stage 1 faults in the handler to the guest through a newly added
> vfio_device_ops callback.
Are there proposed in-kernel drivers that would use any of these
symbols?
> Signed-off-by: Shenming Lu <lushenming@...wei.com>
> ---
> drivers/vfio/vfio.c | 81 +++++++++++++++++++++++++++++++++
> drivers/vfio/vfio_iommu_type1.c | 49 +++++++++++++++++++-
> include/linux/vfio.h | 12 +++++
> 3 files changed, 141 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 44c8dfabf7de..4245f15914bf 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -2356,6 +2356,87 @@ struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group)
> }
> EXPORT_SYMBOL_GPL(vfio_group_iommu_domain);
>
> +/*
> + * Register/Update the VFIO IOPF 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_handler))
> + ret = driver->ops->register_handler(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_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_handler))
> + ret = driver->ops->unregister_handler(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);
> +
> +int vfio_transfer_iommu_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_iommu_fault);
> +
> /**
> * Module/class support
> */
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index ba2b5a1cf6e9..9d1adeddb303 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -3821,13 +3821,32 @@ static int vfio_iommu_type1_dma_map_iopf(struct iommu_fault *fault, void *data)
> struct vfio_batch batch;
> struct vfio_range *range;
> dma_addr_t iova = ALIGN_DOWN(fault->prm.addr, PAGE_SIZE);
> - int access_flags = 0;
> + int access_flags = 0, nested;
> size_t premap_len, map_len, mapped_len = 0;
> unsigned long bit_offset, vaddr, pfn, i, npages;
> int ret;
> enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
> struct iommu_page_response resp = {0};
>
> + if (vfio_dev_domian_nested(dev, &nested))
> + return -ENODEV;
> +
> + /*
> + * When configured in nested mode, further deliver the
> + * stage/level 1 faults to the guest.
> + */
> + if (nested) {
> + bool l2;
> +
> + if (fault->type == IOMMU_FAULT_PAGE_REQ)
> + l2 = fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_L2;
> + if (fault->type == IOMMU_FAULT_DMA_UNRECOV)
> + l2 = fault->event.flags & IOMMU_FAULT_UNRECOV_L2;
> +
> + if (!l2)
> + return vfio_transfer_iommu_fault(dev, fault);
> + }
> +
> if (fault->type != IOMMU_FAULT_PAGE_REQ)
> return -EOPNOTSUPP;
>
> @@ -4201,6 +4220,32 @@ static void vfio_iommu_type1_notify(void *iommu_data,
> wake_up_all(&iommu->vaddr_wait);
> }
>
> +static int vfio_iommu_type1_register_handler(void *iommu_data,
> + struct device *dev)
> +{
> + struct vfio_iommu *iommu = iommu_data;
> +
> + if (iommu->iopf_enabled)
> + return iommu_update_device_fault_handler(dev, ~0,
> + FAULT_REPORT_NESTED_L1);
> + else
> + return iommu_register_device_fault_handler(dev,
> + vfio_iommu_type1_dma_map_iopf,
> + FAULT_REPORT_NESTED_L1, dev);
> +}
> +
> +static int vfio_iommu_type1_unregister_handler(void *iommu_data,
> + struct device *dev)
> +{
> + struct vfio_iommu *iommu = iommu_data;
> +
> + if (iommu->iopf_enabled)
> + return iommu_update_device_fault_handler(dev,
> + ~FAULT_REPORT_NESTED_L1, 0);
> + else
> + return iommu_unregister_device_fault_handler(dev);
> +}
The path through vfio to register this is pretty ugly, but I don't see
any reason for the the update interfaces here, the previously
registered handler just changes its behavior.
> +
> static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
> .name = "vfio-iommu-type1",
> .owner = THIS_MODULE,
> @@ -4216,6 +4261,8 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
> .dma_rw = vfio_iommu_type1_dma_rw,
> .group_iommu_domain = vfio_iommu_type1_group_iommu_domain,
> .notify = vfio_iommu_type1_notify,
> + .register_handler = vfio_iommu_type1_register_handler,
> + .unregister_handler = vfio_iommu_type1_unregister_handler,
> };
>
> static int __init vfio_iommu_type1_init(void)
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index a7b426d579df..4621d8f0395d 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -29,6 +29,8 @@
> * @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 stage/level 1 faults to the guest
> + * for nested mode.
> */
> struct vfio_device_ops {
> char *name;
> @@ -43,6 +45,7 @@ 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);
> @@ -100,6 +103,10 @@ struct vfio_iommu_driver_ops {
> struct iommu_group *group);
> void (*notify)(void *iommu_data,
> enum vfio_iommu_notify_type event);
> + int (*register_handler)(void *iommu_data,
> + struct device *dev);
> + int (*unregister_handler)(void *iommu_data,
> + struct device *dev);
> };
>
> extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
> @@ -161,6 +168,11 @@ extern int vfio_unregister_notifier(struct device *dev,
> struct kvm;
> extern void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm);
>
> +extern int vfio_iommu_dev_fault_handler_register_nested(struct device *dev);
> +extern int vfio_iommu_dev_fault_handler_unregister_nested(struct device *dev);
> +extern int vfio_transfer_iommu_fault(struct device *dev,
> + struct iommu_fault *fault);
> +
> /*
> * Sub-module helpers
> */
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