On 2021/5/25 6:11, Alex Williamson wrote: > 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? If we could register more than one handler per device, things would become much more simple, and the path through vfio-core would not be needed. Hi Baolu, Is there any restriction for having more than one handler per device? > >> 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, I will pay more attention to the IOASID work. Thanks, Shenming > > Alex > > . >
