Move the lock/flush_mem operations around the gpuvm_sm_[un]map() calls so we can implement true atomic page updates, where any access in the locked range done by the GPU has to wait for the page table updates to land before proceeding.
This is needed for vkQueueBindSparse(), so we can replace the dummy page mapped over the entire object by actual BO backed pages in an atomic way. But it's also useful to avoid "AS_ACTIVE bit stuck" failures in the sm_[un]map() path, leading to gpuvm state inconsistencies. Signed-off-by: Boris Brezillon <[email protected]> --- drivers/gpu/drm/panthor/panthor_mmu.c | 182 +++++++++++++------------- 1 file changed, 90 insertions(+), 92 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c index 58fead90533a..ea886c8ac97f 100644 --- a/drivers/gpu/drm/panthor/panthor_mmu.c +++ b/drivers/gpu/drm/panthor/panthor_mmu.c @@ -389,6 +389,15 @@ struct panthor_vm { * flagged as faulty as a result. */ bool unhandled_fault; + + /** @locked_region: Information about the currently locked region currently. */ + struct { + /** @locked_region.start: Start of the locked region. */ + u64 start; + + /** @locked_region.size: Size of the locked region. */ + u64 size; + } locked_region; }; /** @@ -570,79 +579,9 @@ static void lock_region(struct panthor_device *ptdev, u32 as_nr, write_cmd(ptdev, as_nr, AS_COMMAND_LOCK); } -static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr, - u64 iova, u64 size, u32 op) -{ - const u32 l2_flush_op = CACHE_CLEAN | CACHE_INV; - u32 lsc_flush_op; - int ret; - - lockdep_assert_held(&ptdev->mmu->as.slots_lock); - - switch (op) { - case AS_COMMAND_FLUSH_MEM: - lsc_flush_op = CACHE_CLEAN | CACHE_INV; - break; - case AS_COMMAND_FLUSH_PT: - lsc_flush_op = 0; - break; - default: - drm_WARN(&ptdev->base, 1, "Unexpected AS_COMMAND: %d", op); - return -EINVAL; - } - - if (as_nr < 0) - return 0; - - /* - * If the AS number is greater than zero, then we can be sure - * the device is up and running, so we don't need to explicitly - * power it up - */ - - lock_region(ptdev, as_nr, iova, size); - - ret = wait_ready(ptdev, as_nr); - if (ret) - return ret; - - ret = panthor_gpu_flush_caches(ptdev, l2_flush_op, lsc_flush_op, 0); - if (ret) - return ret; - - /* - * Explicitly unlock the region as the AS is not unlocked automatically - * at the end of the GPU_CONTROL cache flush command, unlike - * AS_COMMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT. - */ - write_cmd(ptdev, as_nr, AS_COMMAND_UNLOCK); - - /* Wait for the unlock command to complete */ - return wait_ready(ptdev, as_nr); -} - -static int mmu_hw_do_operation(struct panthor_vm *vm, - u64 iova, u64 size, u32 op) -{ - struct panthor_device *ptdev = vm->ptdev; - int ret; - - mutex_lock(&ptdev->mmu->as.slots_lock); - ret = mmu_hw_do_operation_locked(ptdev, vm->as.id, iova, size, op); - mutex_unlock(&ptdev->mmu->as.slots_lock); - - return ret; -} - static int panthor_mmu_as_enable(struct panthor_device *ptdev, u32 as_nr, u64 transtab, u64 transcfg, u64 memattr) { - int ret; - - ret = mmu_hw_do_operation_locked(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM); - if (ret) - return ret; - gpu_write64(ptdev, AS_TRANSTAB(as_nr), transtab); gpu_write64(ptdev, AS_MEMATTR(as_nr), memattr); gpu_write64(ptdev, AS_TRANSCFG(as_nr), transcfg); @@ -654,7 +593,9 @@ static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr) { int ret; - ret = mmu_hw_do_operation_locked(ptdev, as_nr, 0, ~0ULL, AS_COMMAND_FLUSH_MEM); + /* Flush and invalidate all caches. */ + write_cmd(ptdev, as_nr, AS_COMMAND_FLUSH_MEM); + ret = wait_ready(ptdev, as_nr); if (ret) return ret; @@ -736,6 +677,10 @@ int panthor_vm_active(struct panthor_vm *vm) if (refcount_inc_not_zero(&vm->as.active_cnt)) goto out_dev_exit; + /* Make sure we don't race with lock/unlock_region() calls + * happening around VM bind operations. + */ + mutex_lock(&vm->op_lock); mutex_lock(&ptdev->mmu->as.slots_lock); if (refcount_inc_not_zero(&vm->as.active_cnt)) @@ -803,6 +748,10 @@ int panthor_vm_active(struct panthor_vm *vm) gpu_write(ptdev, MMU_INT_MASK, ~ptdev->mmu->as.faulty_mask); } + /* The VM update is guarded by ::op_lock, which we take at the beginning + * of this function, so we don't expect any locked region here. + */ + drm_WARN_ON(&vm->ptdev->base, vm->locked_region.size > 0); ret = panthor_mmu_as_enable(vm->ptdev, vm->as.id, transtab, transcfg, vm->memattr); out_make_active: @@ -813,6 +762,7 @@ int panthor_vm_active(struct panthor_vm *vm) out_unlock: mutex_unlock(&ptdev->mmu->as.slots_lock); + mutex_unlock(&vm->op_lock); out_dev_exit: drm_dev_exit(cookie); @@ -896,30 +846,15 @@ static size_t get_pgsize(u64 addr, size_t size, size_t *count) return SZ_2M; } -static int panthor_vm_flush_range(struct panthor_vm *vm, u64 iova, u64 size) -{ - struct panthor_device *ptdev = vm->ptdev; - int ret = 0, cookie; - - if (vm->as.id < 0) - return 0; - - /* If the device is unplugged, we just silently skip the flush. */ - if (!drm_dev_enter(&ptdev->base, &cookie)) - return 0; - - ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT); - - drm_dev_exit(cookie); - return ret; -} - static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size) { struct panthor_device *ptdev = vm->ptdev; struct io_pgtable_ops *ops = vm->pgtbl_ops; u64 offset = 0; + drm_WARN_ON(&ptdev->base, + (iova < vm->locked_region.start) || + (iova + size > vm->locked_region.start + vm->locked_region.size)); drm_dbg(&ptdev->base, "unmap: as=%d, iova=%llx, len=%llx", vm->as.id, iova, size); while (offset < size) { @@ -933,13 +868,12 @@ static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size) iova + offset + unmapped_sz, iova + offset + pgsize * pgcount, iova, iova + size); - panthor_vm_flush_range(vm, iova, offset + unmapped_sz); return -EINVAL; } offset += unmapped_sz; } - return panthor_vm_flush_range(vm, iova, size); + return 0; } static int @@ -956,6 +890,10 @@ panthor_vm_map_pages(struct panthor_vm *vm, u64 iova, int prot, if (!size) return 0; + drm_WARN_ON(&ptdev->base, + (iova < vm->locked_region.start) || + (iova + size > vm->locked_region.start + vm->locked_region.size)); + for_each_sgtable_dma_sg(sgt, sgl, count) { dma_addr_t paddr = sg_dma_address(sgl); size_t len = sg_dma_len(sgl); @@ -1003,7 +941,7 @@ panthor_vm_map_pages(struct panthor_vm *vm, u64 iova, int prot, offset = 0; } - return panthor_vm_flush_range(vm, start_iova, iova - start_iova); + return 0; } static int flags_to_prot(u32 flags) @@ -1672,6 +1610,56 @@ static const char *access_type_name(struct panthor_device *ptdev, } } +static int panthor_vm_lock_region(struct panthor_vm *vm, u64 start, u64 size) +{ + struct panthor_device *ptdev = vm->ptdev; + int ret = 0; + + mutex_lock(&ptdev->mmu->as.slots_lock); + drm_WARN_ON(&ptdev->base, vm->locked_region.start || vm->locked_region.size); + vm->locked_region.start = start; + vm->locked_region.size = size; + if (vm->as.id >= 0) { + lock_region(ptdev, vm->as.id, start, size); + + /* If the lock failed, reset the locked region. */ + ret = wait_ready(ptdev, vm->as.id); + if (ret) { + vm->locked_region.start = 0; + vm->locked_region.size = 0; + } + } + mutex_unlock(&ptdev->mmu->as.slots_lock); + + return ret; +} + +static void panthor_vm_unlock_region(struct panthor_vm *vm) +{ + struct panthor_device *ptdev = vm->ptdev; + + mutex_lock(&ptdev->mmu->as.slots_lock); + if (vm->as.id >= 0) { + int ret; + + /* FLUSH_MEM will flush all cache entries covering + * the locked region and unlock it. + */ + ret = write_cmd(ptdev, vm->as.id, AS_COMMAND_FLUSH_MEM); + if (!ret) + ret = wait_ready(ptdev, vm->as.id); + + /* If we fail to unlock the region, schedule a GPU reset + * to unblock the situation. + */ + if (drm_WARN_ON(&ptdev->base, ret)) + panthor_device_schedule_reset(ptdev); + } + vm->locked_region.start = 0; + vm->locked_region.size = 0; + mutex_unlock(&ptdev->mmu->as.slots_lock); +} + static void panthor_mmu_irq_handler(struct panthor_device *ptdev, u32 status) { bool has_unhandled_faults = false; @@ -1876,6 +1864,7 @@ static void panthor_vm_free(struct drm_gpuvm *gpuvm) drm_sched_entity_destroy(&vm->entity); drm_sched_fini(&vm->sched); + mutex_lock(&vm->op_lock); mutex_lock(&ptdev->mmu->as.slots_lock); if (vm->as.id >= 0) { int cookie; @@ -1890,6 +1879,7 @@ static void panthor_vm_free(struct drm_gpuvm *gpuvm) list_del(&vm->as.lru_node); } mutex_unlock(&ptdev->mmu->as.slots_lock); + mutex_unlock(&vm->op_lock); free_io_pgtable_ops(vm->pgtbl_ops); @@ -2197,6 +2187,11 @@ panthor_vm_exec_op(struct panthor_vm *vm, struct panthor_vm_op_ctx *op, mutex_lock(&vm->op_lock); vm->op_ctx = op; + + ret = panthor_vm_lock_region(vm, op->va.addr, op->va.range); + if (ret) + goto out; + switch (op_type) { case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP: { const struct drm_gpuvm_map_req map_req = { @@ -2224,6 +2219,9 @@ panthor_vm_exec_op(struct panthor_vm *vm, struct panthor_vm_op_ctx *op, break; } + panthor_vm_unlock_region(vm); + +out: if (ret && flag_vm_unusable_on_failure) vm->unusable = true; -- 2.51.0
