109 lines
3.8 KiB
ReStructuredText
109 lines
3.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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===================
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VFIO virtual device
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===================
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Device types supported:
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- KVM_DEV_TYPE_VFIO
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Only one VFIO instance may be created per VM. The created device
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tracks VFIO files (group or device) in use by the VM and features
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of those groups/devices important to the correctness and acceleration
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of the VM. As groups/devices are enabled and disabled for use by the
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VM, KVM should be updated about their presence. When registered with
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KVM, a reference to the VFIO file is held by KVM.
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Groups:
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KVM_DEV_VFIO_FILE
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alias: KVM_DEV_VFIO_GROUP
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KVM_DEV_VFIO_PVIOMMU
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KVM_DEV_VFIO_FILE attributes:
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KVM_DEV_VFIO_FILE_ADD: Add a VFIO file (group/device) to VFIO-KVM device
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tracking
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kvm_device_attr.addr points to an int32_t file descriptor for the
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VFIO file.
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KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from VFIO-KVM
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device tracking
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kvm_device_attr.addr points to an int32_t file descriptor for the
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VFIO file.
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KVM_DEV_VFIO_GROUP (legacy kvm device group restricted to the handling of VFIO group fd):
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KVM_DEV_VFIO_GROUP_ADD: same as KVM_DEV_VFIO_FILE_ADD for group fd only
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KVM_DEV_VFIO_GROUP_DEL: same as KVM_DEV_VFIO_FILE_DEL for group fd only
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KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
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allocated by sPAPR KVM.
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kvm_device_attr.addr points to a struct::
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struct kvm_vfio_spapr_tce {
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__s32 groupfd;
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__s32 tablefd;
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};
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where:
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- @groupfd is a file descriptor for a VFIO group;
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- @tablefd is a file descriptor for a TCE table allocated via
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KVM_CREATE_SPAPR_TCE.
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The FILE/GROUP_ADD operation above should be invoked prior to accessing the
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device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support
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drivers which require a kvm pointer to be set in their .open_device()
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callback. It is the same for device file descriptor via character device
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open which gets device access via VFIO_DEVICE_BIND_IOMMUFD. For such file
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descriptors, FILE_ADD should be invoked before VFIO_DEVICE_BIND_IOMMUFD
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to support the drivers mentioned in prior sentence as well.
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KVM_DEV_VFIO_PVIOMMU attributes:
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KVM_DEV_VFIO_PVIOMMU_ATTACH: Create and attach a pvIOMMU instance to the
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KVM VM associated with this device, returns a file descriptor "pviommufd"
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for this IOMMU which supports some IOCTLs.
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KVM_DEV_VFIO_PVIOMMU_GET_INFO: Retrieve information about IOMMUs for a VFIO
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devicefd, using the following struct:
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struct kvm_vfio_iommu_info {
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__u32 size;
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__s32 device_fd;
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__u32 out_nr_sids;
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__u32 __reserved;
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};
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Where kvm_vfio_iommu_info.device_fd the input VFIO device ID, and
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kvm_vfio_iommu_info.out_nr_sids is the number stream IDs(endpoint) for
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this device, this similar to VFIO_DEVICE_GET_IRQ_INFO which returns the
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number of irqs for a VFIO device.
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size is added to allow the struct to be extended, while __reserved
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must be zero.
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The rest of the IOCTLs are used to configure the pvIOMMU are part of
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the pviommufd returned from the attach operation:
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KVM_PVIOMMU_SET_CONFIG: Configure pvIOMMU for an endpoint for a device,
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where the input struct:
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struct kvm_vfio_iommu_config {
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__u32 size;
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__s32 device_fd;
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__u32 sid_idx;
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__u32 vsid;
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__u32 __reserved;
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};
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kvm_vfio_iommu_config.device_fd is the VFIO devicefd,
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kvm_vfio_iommu_config.sid_idx is a valid index based on number of sids
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from KVM_DEV_VFIO_PVIOMMU_GET_INFO.
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And kvm_vfio_iommu_config.vsid is the virtual sid seen by the guest,
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It is the VMM responsibility to describe this to the guest, the pvIOMMU
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would translate an IOMMU request with this vsid to the physical SID of
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the device for the index specified.
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This is similar to VFIO IOCTL VFIO_DEVICE_SET_IRQS but for the IOMMU.
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size is added to allow the struct to be extended, while __reserved
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must be zero.
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