drivers/gpu/drm/xe/xe_sriov_vf.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/xe/xe_sriov_vf.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/xe/xe_sriov_vf.c
Extension
.c
Size
13026 bytes
Lines
287
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2023-2024 Intel Corporation
 */

#include <drm/drm_debugfs.h>
#include <drm/drm_managed.h>

#include "xe_gt_sriov_vf.h"
#include "xe_guc.h"
#include "xe_sriov_printk.h"
#include "xe_sriov_vf.h"
#include "xe_sriov_vf_ccs.h"

/**
 * DOC: VF restore procedure in PF KMD and VF KMD
 *
 * Restoring previously saved state of a VF is one of core features of
 * SR-IOV. All major VM Management applications allow saving and restoring
 * the VM state, and doing that to a VM which uses SRIOV VF as one of
 * the accessible devices requires support from KMD on both PF and VF side.
 * VMM initiates all required operations through VFIO module, which then
 * translates them into PF KMD calls. This description will focus on these
 * calls, leaving out the module which initiates these steps (VFIO).
 *
 * In order to start the restore procedure, GuC needs to keep the VF in
 * proper state. The PF driver can ensure GuC set it to VF_READY state
 * by provisioning the VF, which in turn can be done after Function Level
 * Reset of said VF (or after it was freshly created - in that case FLR
 * is not needed). The FLR procedure ends with GuC sending message
 * `GUC_PF_NOTIFY_VF_FLR_DONE`, and then provisioning data is sent to GuC.
 * After the provisioning is completed, the VF needs to be paused, and
 * at that point the actual restore can begin.
 *
 * During VF Restore, state of several resources is restored. These may
 * include local memory content (system memory is restored by VMM itself),
 * values of MMIO registers, stateless compression metadata and others.
 * The final resource which also needs restoring is state of the VF
 * submission maintained within GuC. For that, `GUC_PF_OPCODE_VF_RESTORE`
 * message is used, with reference to the state blob to be consumed by
 * GuC.
 *
 * Next, when VFIO is asked to set the VM into running state, the PF driver
 * sends `GUC_PF_TRIGGER_VF_RESUME` to GuC. When sent after restore, this
 * changes VF state within GuC to `VF_RESFIX_BLOCKED` rather than the
 * usual `VF_RUNNING`. At this point GuC triggers an interrupt to inform
 * the VF KMD within the VM that it was migrated.
 *
 * As soon as Virtual GPU of the VM starts, the VF driver within receives
 * the MIGRATED interrupt and schedules post-migration recovery worker.
 * That worker sends `VF2GUC_RESFIX_START` action along with non-zero
 * marker, queries GuC for new provisioning (using MMIO communication),
 * and applies fixups to any non-virtualized resources used by the VF.
 *
 * When the VF driver is ready to continue operation on the newly connected
 * hardware, it sends `VF2GUC_RESFIX_DONE` action along with the same
 * marker which was sent with `VF2GUC_RESFIX_START` which causes it to
 * enter the long awaited `VF_RUNNING` state, and therefore start handling
 * CTB messages and scheduling workloads from the VF::
 *
 *      PF                             GuC                              VF
 *     [ ]                              |                               |
 *     [ ] PF2GUC_VF_CONTROL(pause)     |                               |
 *     [ ]---------------------------> [ ]                              |
 *     [ ]                             [ ]  GuC sets new VF state to    |
 *     [ ]                             [ ]------- VF_READY_PAUSED       |
 *     [ ]                             [ ]      |                       |
 *     [ ]                             [ ] <-----                       |
 *     [ ] success                     [ ]                              |
 *     [ ] <---------------------------[ ]                              |
 *     [ ]                              |                               |
 *     [ ] PF loads resources from the  |                               |
 *     [ ]------- saved image supplied  |                               |
 *     [ ]      |                       |                               |
 *     [ ] <-----                       |                               |
 *     [ ]                              |                               |
 *     [ ] GUC_PF_OPCODE_VF_RESTORE     |                               |
 *     [ ]---------------------------> [ ]                              |
 *     [ ]                             [ ]  GuC loads contexts and CTB  |
 *     [ ]                             [ ]------- state from image      |
 *     [ ]                             [ ]      |                       |
 *     [ ]                             [ ] <-----                       |
 *     [ ]                             [ ]                              |
 *     [ ]                             [ ]  GuC sets new VF state to    |
 *     [ ]                             [ ]------- VF_RESFIX_PAUSED      |
 *     [ ]                             [ ]      |                       |
 *     [ ] success                     [ ] <-----                       |
 *     [ ] <---------------------------[ ]                              |
 *     [ ]                              |                               |
 *     [ ] GUC_PF_TRIGGER_VF_RESUME     |                               |

Annotation

Implementation Notes