Re: [PATCH v2] drm/amdgpu: reset vm state machine after gpu reset(vram lost)

[Christian König]

Am 23.07.24 um 05:05 schrieb ZhenGuo Yin:

[Why]
Page table of compute VM in the VRAM will lost after gpu reset.
VRAM won't be restored since compute VM has no shadows.

[How]
Use higher 32-bit of vm->generation to record a vram_lost_counter.
Reset the VM state machine when vm->genertaion is not equal to
re-generation token.

v2: Check vm->generation instead of calling drm_sched_entity_error
in amdgpu_vm_validate.

Signed-off-by: ZhenGuo Yin <zhenguo....@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 11 +++++++----
  1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 3abfa66d72a2..9e2f84c166e7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -434,7 +434,7 @@ uint64_t amdgpu_vm_generation(struct amdgpu_device *adev, 
struct amdgpu_vm *vm)
        if (!vm)
                return result;

- result += vm->generation;

+       result += (vm->generation & 0xFFFFFFFF);
        /* Add one if the page tables will be re-generated on next CS */
        if (drm_sched_entity_error(&vm->delayed))
                ++result;
@@ -467,9 +467,12 @@ int amdgpu_vm_validate(struct amdgpu_device *adev, struct 
amdgpu_vm *vm,
        struct amdgpu_bo *shadow;
        struct amdgpu_bo *bo;
        int r;
+       uint32_t vram_lost_counter = atomic_read(&adev->vram_lost_counter);

In general please sort the longer lines first.

And use amdgpu_vm_generation(adev, vm) here to get the new generation value.

- if (drm_sched_entity_error(&vm->delayed)) {

-               ++vm->generation;
+       if (vm->generation != amdgpu_vm_generation(adev, vm)) {
+               if (drm_sched_entity_error(&vm->delayed))
+                       ++vm->generation;
+               vm->generation = (u64)vram_lost_counter << 32 | (vm->generation 
& 0xFFFFFFFF);

And then test and assign that new generation value here.

                amdgpu_vm_bo_reset_state_machine(vm);
                amdgpu_vm_fini_entities(vm);
                r = amdgpu_vm_init_entities(adev, vm);
@@ -2439,7 +2442,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct 
amdgpu_vm *vm,
        vm->last_update = dma_fence_get_stub();
        vm->last_unlocked = dma_fence_get_stub();
        vm->last_tlb_flush = dma_fence_get_stub();
-       vm->generation = 0;
+       vm->generation = (u64)atomic_read(&adev->vram_lost_counter) << 32;

Use amdgpu_vm_generation(adev, NULL) to initialize this.

Regards,
Christian.

mutex_init(&vm->eviction_lock);

        vm->evicting = false;