[PATCH v3.1] drm/xe: Implement VM snapshot support for BO's and userptr
Maarten Lankhorst
maarten.lankhorst at linux.intel.com
Tue Feb 13 14:28:32 UTC 2024
Hey,
On 2024-02-05 17:47, Souza, Jose wrote:
> On Fri, 2024-02-02 at 23:45 +0100, Maarten Lankhorst wrote:
>> Since we cannot immediately capture the BO's and userptr, perform it in
>> 2 stages. The immediate stage takes a reference to each BO and userptr,
>> while a delayed worker captures the contents and then frees the
>> reference.
>>
>> This is required because in signaling context, no locks can be taken, no
>> memory can be allocated, and no waits on userspace can be performed.
>>
>> With the delayed worker, all of this can be performed very easily,
>> without having to resort to hacks.
>>
>> Changes since v1:
>> - Fix crash on NULL captured vm.
>> - Use ascii85_encode to capture BO contents and save some space.
>> - Add length to coredump output for each captured area.
>> Changes since v2:
>> - Dump each mapping on their own line, to simplify tooling.
>> - Fix null pointer deref in xe_vm_snapshot_free.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> ---
>> drivers/gpu/drm/xe/xe_devcoredump.c | 33 ++++-
>> drivers/gpu/drm/xe/xe_devcoredump_types.h | 8 ++
>> drivers/gpu/drm/xe/xe_vm.c | 162 ++++++++++++++++++++++
>> drivers/gpu/drm/xe/xe_vm.h | 5 +
>> 4 files changed, 206 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
>> index 08d3f6cb72292..3e863e51b9d4d 100644
>> --- a/drivers/gpu/drm/xe/xe_devcoredump.c
>> +++ b/drivers/gpu/drm/xe/xe_devcoredump.c
>> @@ -17,6 +17,7 @@
>> #include "xe_guc_submit.h"
>> #include "xe_hw_engine.h"
>> #include "xe_sched_job.h"
>> +#include "xe_vm.h"
>>
>> /**
>> * DOC: Xe device coredump
>> @@ -59,12 +60,22 @@ static struct xe_guc *exec_queue_to_guc(struct xe_exec_queue *q)
>> return &q->gt->uc.guc;
>> }
>>
>> +static void xe_devcoredump_deferred_snap_work(struct work_struct *work)
>> +{
>> + struct xe_devcoredump_snapshot *ss = container_of(work, typeof(*ss), work);
>> +
>> + xe_force_wake_get(gt_to_fw(ss->gt), XE_FORCEWAKE_ALL);
>> + if (ss->vm)
>> + xe_vm_snapshot_capture_delayed(ss->vm);
>> + xe_force_wake_put(gt_to_fw(ss->gt), XE_FORCEWAKE_ALL);
>> +}
>> +
>> static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
>> size_t count, void *data, size_t datalen)
>> {
>> struct xe_devcoredump *coredump = data;
>> struct xe_device *xe = coredump_to_xe(coredump);
>> - struct xe_devcoredump_snapshot *ss;
>> + struct xe_devcoredump_snapshot *ss = &coredump->snapshot;
>> struct drm_printer p;
>> struct drm_print_iterator iter;
>> struct timespec64 ts;
>> @@ -74,12 +85,14 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
>> if (!data || !coredump_to_xe(coredump))
>> return -ENODEV;
>>
>> + /* Ensure delayed work is captured before continuing */
>> + flush_work(&ss->work);
>> +
>> iter.data = buffer;
>> iter.offset = 0;
>> iter.start = offset;
>> iter.remain = count;
>>
>> - ss = &coredump->snapshot;
>> p = drm_coredump_printer(&iter);
>>
>> drm_printf(&p, "**** Xe Device Coredump ****\n");
>> @@ -104,6 +117,10 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
>> if (coredump->snapshot.hwe[i])
>> xe_hw_engine_snapshot_print(coredump->snapshot.hwe[i],
>> &p);
>> + if (coredump->snapshot.vm) {
>> + drm_printf(&p, "\n**** VM state ****\n");
>> + xe_vm_snapshot_print(coredump->snapshot.vm, &p);
>> + }
>>
>> return count - iter.remain;
>> }
>> @@ -117,12 +134,16 @@ static void xe_devcoredump_free(void *data)
>> if (!data || !coredump_to_xe(coredump))
>> return;
>>
>> + cancel_work_sync(&coredump->snapshot.work);
>> +
>> xe_guc_ct_snapshot_free(coredump->snapshot.ct);
>> xe_guc_exec_queue_snapshot_free(coredump->snapshot.ge);
>> xe_sched_job_snapshot_free(coredump->snapshot.job);
>> for (i = 0; i < XE_NUM_HW_ENGINES; i++)
>> if (coredump->snapshot.hwe[i])
>> xe_hw_engine_snapshot_free(coredump->snapshot.hwe[i]);
>> + xe_vm_snapshot_free(coredump->snapshot.vm);
>> + memset(&coredump->snapshot, 0, sizeof(coredump->snapshot));
>>
>> coredump->captured = false;
>> drm_info(&coredump_to_xe(coredump)->drm,
>> @@ -145,6 +166,9 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
>> ss->snapshot_time = ktime_get_real();
>> ss->boot_time = ktime_get_boottime();
>>
>> + ss->gt = q->gt;
>> + INIT_WORK(&ss->work, xe_devcoredump_deferred_snap_work);
>> +
>> cookie = dma_fence_begin_signalling();
>> for (i = 0; q->width > 1 && i < XE_HW_ENGINE_MAX_INSTANCE;) {
>> if (adj_logical_mask & BIT(i)) {
>> @@ -160,6 +184,7 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
>> coredump->snapshot.ct = xe_guc_ct_snapshot_capture(&guc->ct, true);
>> coredump->snapshot.ge = xe_guc_exec_queue_snapshot_capture(job);
>> coredump->snapshot.job = xe_sched_job_snapshot_capture(job);
>> + coredump->snapshot.vm = xe_vm_snapshot_capture(q->vm);
>>
>> for_each_hw_engine(hwe, q->gt, id) {
>> if (hwe->class != q->hwe->class ||
>> @@ -170,6 +195,9 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
>> coredump->snapshot.hwe[id] = xe_hw_engine_snapshot_capture(hwe);
>> }
>>
>> + if (ss->vm)
>> + queue_work(system_unbound_wq, &ss->work);
>> +
>> xe_force_wake_put(gt_to_fw(q->gt), XE_FORCEWAKE_ALL);
>> dma_fence_end_signalling(cookie);
>> }
>> @@ -203,3 +231,4 @@ void xe_devcoredump(struct xe_sched_job *job)
>> xe_devcoredump_read, xe_devcoredump_free);
>> }
>> #endif
>> +
>> diff --git a/drivers/gpu/drm/xe/xe_devcoredump_types.h b/drivers/gpu/drm/xe/xe_devcoredump_types.h
>> index d259119b2c980..b389c1a298e3d 100644
>> --- a/drivers/gpu/drm/xe/xe_devcoredump_types.h
>> +++ b/drivers/gpu/drm/xe/xe_devcoredump_types.h
>> @@ -12,6 +12,7 @@
>> #include "xe_hw_engine_types.h"
>>
>> struct xe_device;
>> +struct xe_gt;
>>
>> /**
>> * struct xe_devcoredump_snapshot - Crash snapshot
>> @@ -26,6 +27,11 @@ struct xe_devcoredump_snapshot {
>> /** @boot_time: Relative boot time so the uptime can be calculated. */
>> ktime_t boot_time;
>>
>> + /** @gt: Affected GT, used by forcewake for delayed capture */
>> + struct xe_gt *gt;
>> + /** @work: Workqueue for deffered capture outside of signaling context */
>> + struct work_struct work;
>> +
>> /* GuC snapshots */
>> /** @ct: GuC CT snapshot */
>> struct xe_guc_ct_snapshot *ct;
>> @@ -36,6 +42,8 @@ struct xe_devcoredump_snapshot {
>> struct xe_hw_engine_snapshot *hwe[XE_NUM_HW_ENGINES];
>> /** @job: Snapshot of job state */
>> struct xe_sched_job_snapshot *job;
>> + /** @vm: Snapshot of VM state */
>> + struct xe_vm_snapshot *vm;
>> };
>>
>> /**
>> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
>> index 1f0d58bfd1046..6965fe15bcbea 100644
>> --- a/drivers/gpu/drm/xe/xe_vm.c
>> +++ b/drivers/gpu/drm/xe/xe_vm.c
>> @@ -13,6 +13,7 @@
>> #include <drm/ttm/ttm_execbuf_util.h>
>> #include <drm/ttm/ttm_tt.h>
>> #include <drm/xe_drm.h>
>> +#include <linux/ascii85.h>
>> #include <linux/delay.h>
>> #include <linux/kthread.h>
>> #include <linux/mm.h>
>> @@ -3267,3 +3268,164 @@ int xe_analyze_vm(struct drm_printer *p, struct xe_vm *vm, int gt_id)
>>
>> return 0;
>> }
>> +
>> +struct xe_vm_snapshot {
>> + unsigned long num_snaps;
>> + struct {
>> + uint64_t ofs, bo_ofs;
>> + unsigned long len;
>> + struct xe_bo *bo;
>> + void *data;
>> + struct mm_struct *mm;
>> + } snap[];
>> +};
>> +
>> +struct xe_vm_snapshot *xe_vm_snapshot_capture(struct xe_vm *vm)
>> +{
>> + unsigned long num_snaps = 0, i;
>> + struct xe_vm_snapshot *snap = NULL;
>> + struct drm_gpuva *gpuva;
>> +
>> + if (!vm)
>> + return NULL;
>> +
>> + mutex_lock(&vm->snap_mutex);
>> + drm_gpuvm_for_each_va(gpuva, &vm->gpuvm) {
>> + if (gpuva->flags & XE_VMA_DUMPABLE)
>> + num_snaps++;
>> + }
>> +
>> + if (num_snaps)
>> + snap = kvzalloc(offsetof(struct xe_vm_snapshot, snap[num_snaps]), GFP_NOWAIT);
>> + if (!snap)
>> + goto out_unlock;
>> +
>> + snap->num_snaps = num_snaps;
>> + i = 0;
>> + drm_gpuvm_for_each_va(gpuva, &vm->gpuvm) {
>> + struct xe_vma *vma = gpuva_to_vma(gpuva);
>> + struct xe_bo *bo = vma->gpuva.gem.obj ?
>> + gem_to_xe_bo(vma->gpuva.gem.obj) : NULL;
>> +
>> + if (!(gpuva->flags & XE_VMA_DUMPABLE))
>> + continue;
>> +
>> + snap->snap[i].ofs = xe_vma_start(vma);
>> + snap->snap[i].len = xe_vma_size(vma);
>> + if (bo) {
>> + snap->snap[i].bo = xe_bo_get(bo);
>> + snap->snap[i].bo_ofs = xe_vma_bo_offset(vma);
>> + } else if (xe_vma_is_userptr(vma)) {
>> + struct xe_userptr *userptr = &to_userptr_vma(vma)->userptr;
>> + if (mmget_not_zero(userptr->notifier.mm))
>> + snap->snap[i].mm = userptr->notifier.mm;
>> + else
>> + snap->snap[i].data = ERR_PTR(-EFAULT);
>> + snap->snap[i].bo_ofs = xe_vma_userptr(vma);
>> + } else {
>> + snap->snap[i].data = ERR_PTR(-ENOENT);
>> + }
>> + i++;
>> + }
>> +
>> +out_unlock:
>> + mutex_unlock(&vm->snap_mutex);
>> + return snap;
>> +}
>> +
>> +void xe_vm_snapshot_capture_delayed(struct xe_vm_snapshot *snap)
>> +{
>> + for (int i = 0; i < snap->num_snaps; i++) {
>> + struct xe_bo *bo = snap->snap[i].bo;
>> + struct iosys_map src;
>> + int err;
>> +
>> + if (IS_ERR(snap->snap[i].data))
>> + continue;
>> +
>> + snap->snap[i].data = kvmalloc(snap->snap[i].len, GFP_USER);
>> + if (!snap->snap[i].data) {
>> + snap->snap[i].data = ERR_PTR(-ENOMEM);
>> + goto cleanup_bo;
>> + }
>> +
>> + if (bo) {
>> + dma_resv_lock(bo->ttm.base.resv, NULL);
>> + err = ttm_bo_vmap(&bo->ttm, &src);
>> + if (!err) {
>> + xe_map_memcpy_from(xe_bo_device(bo),
>> + snap->snap[i].data,
>> + &src, snap->snap[i].bo_ofs,
>> + snap->snap[i].len);
>> + ttm_bo_vunmap(&bo->ttm, &src);
>> + }
>> + dma_resv_unlock(bo->ttm.base.resv);
>> + } else {
>> + void __user *userptr = (void __user *)(size_t)snap->snap[i].bo_ofs;
>> + kthread_use_mm(snap->snap[i].mm);
>> +
>> + if (!copy_from_user(snap->snap[i].data, userptr, snap->snap[i].len))
>> + err = 0;
>> + else
>> + err = -EFAULT;
>> + kthread_unuse_mm(snap->snap[i].mm);
>> + mmput(snap->snap[i].mm);
>> + snap->snap[i].mm = NULL;
>> + }
>> +
>> + if (err) {
>> + kvfree(snap->snap[i].data);
>> + snap->snap[i].data = ERR_PTR(err);
>> + }
>> +
>> +cleanup_bo:
>> + xe_bo_put(bo);
>> + snap->snap[i].bo = NULL;
>> + }
>> +}
>> +
>> +void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer *p)
>> +{
>> + unsigned long i, j;
>> +
>> + for (i = 0; i < snap->num_snaps; i++) {
>> + if (IS_ERR(snap->snap[i].data))
>> + goto uncaptured;
>> +
>> + drm_printf(p, "[%llx].length: 0x%lx\n", snap->snap[i].ofs, snap->snap[i].len);
>> + drm_printf(p, "[%llx].data: ",
>> + snap->snap[i].ofs + j);
>
> j needs to be set to 0 before this drm_printf()
j should not have been there, thanks for catching!
~Maarten
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