On Mon, 24 May 2021 21:11:11 +0800 Shenming Lu <lushenming@xxxxxxxxxx> wrote: > On 2021/5/21 15:59, Shenming Lu wrote: > > On 2021/5/19 2:58, Alex Williamson wrote: > >> On Fri, 9 Apr 2021 11:44:20 +0800 > >> Shenming Lu <lushenming@xxxxxxxxxx> 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? > > > > I hope that such as Eric's SMMUv3 Nested Stage Setup series [1] can > > use these symbols to consolidate the two page fault handlers into one. > > > > [1] https://patchwork.kernel.org/project/kvm/cover/20210411114659.15051-1-eric.auger@xxxxxxxxxx/ > > > >> > >>> Signed-off-by: Shenming Lu <lushenming@xxxxxxxxxx> > >>> --- > >>> 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. > > > > Yeah, this seems not an elegant way... > > > > If IOPF(L2) enabled, the fault handler has already been registered, so for > > nested mode setup, we only need to change the flags of the handler in the > > IOMMU driver to receive L1 faults. > > (assume that L1 IOPF is configured after L2 IOPF) > > > > Currently each device can only have one iommu dev fault handler, and L1 > > and L2 IOPF are configured separately in nested mode, I am also wondering > > that is there a better solution for this. I haven't fully read all the references, but who imposes the fact that there's only one fault handler per device? If type1 could register one handler and the vfio-pci bus driver another for the other level, would we need this path through vfio-core? > Let me simply add, maybe there is another way for this: > Would it be better to set host IOPF enabled (L2 faults) in the VFIO_IOMMU_MAP_DMA > ioctl (no need to add a new ioctl, and we can specify whether this mapping is IOPF > available or statically pinned), and set guest IOPF enabled (L1 faults) in the > VFIO_IOMMU_SET_PASID_TABLE (from Eric's series) ioctl? > And we have no requirement for the sequence of these two ioctls. The first called > one will register the handler, and the later one will just update the handler... This is looking more and more like it belongs with the IOASID work. I think Eric has shifted his focus there too. Thanks, Alex
