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Each buffer is >>> represented by a qda_gem_obj which embeds a drm_gem_object and >>> carries the kernel virtual address, DMA address, and a pointer to >>> the IOMMU device that performed the allocation. The .free callback >>> delegates to the memory manager, and the .mmap callback uses >>> dma_mmap_coherent() via the DMA backend. >>> >>> qda_memory_dma.c / qda_memory_dma.h >>> DMA coherent allocation backend. qda_dma_alloc() calls >>> dma_alloc_coherent() on the CB device and encodes the stream ID >>> (SID) in the upper 32 bits of the returned DMA address, following >>> the Qualcomm FastRPC convention for IOMMU address space tagging. >>> qda_dma_free() strips the SID prefix before calling >>> dma_free_coherent(). >>> >>> qda_memory_manager.c >>> Adds process-to-device assignment: each DRM file (process) is >>> assigned one IOMMU context bank device for the lifetime of the >>> session. qda_memory_manager_assign_device() first checks whether >>> the process already has a device (reusing it with a refcount >>> increment), then falls back to claiming an unassigned device. >>> qda_memory_manager_alloc() and qda_memory_manager_free() delegate >>> to the DMA backend after resolving the correct CB device for the >>> calling process. >> >> Oh, stuff like that is usually a pretty big NO-GO now. >> >> AMD has made the same mistake with KFD and it resulted in a massive chaos. >> >> The DRM file is the driver context your process uses and even if there are multiple DRM files for the same PID you should absolute *NOT* share anything between them. >> >> The general rule of thumb is to not attach anything to the process using the DRM file descriptor. > > A couple other things to keep in mind: > > 1. drm device fd can be passed across processes > 2. virtgpu/virglrenderer drm native ctx is a single process that opens > the drm device file N times on behalf of N guest userspace processes. > > All that to say, Christian is right here.. drm_file is your context, > pgtables should be attached to the drm_file (potentially via > drm_gpuvm.. which you perhaps want to use). Some additional points you should probably keep in mind: 1. In some configurations the DRM fd is not opened by the application but rather by the display server. So you see for example X/XWayland opening the fd. 2. For gdb plugins you now seriously want to use pidfd_getfd() to grab the DRM fd from the debugged process into your debugger process. Hacks with the PID or TGID are something which needs in deep review for correctness. Regards, Christian. > > BR, > -R > >> Regards, >> Christian. >> >>> >>> qda_drv.c / qda_drv.h >>> qda_file_priv gains an assigned_iommu_dev pointer and a pid field. >>> The .postclose callback decrements the IOMMU device refcount and >>> clears the process assignment when the last reference is dropped. >>> >>> Assisted-by: Claude:claude-sonnet-5 >>> Signed-off-by: Ekansh Gupta >>> --- >>> Changes in v2: >>> - Adapt to the dynamically-sized device array introduced in patch 07 >>> (kcalloc'd from DT node count, replaces fixed QDA_IOMMU_DEVICES_MAX) >>> - Protect register/unregister with the process_assignment_lock mutex so >>> the device-assignment and device-registration paths are serialised >>> - No functional changes requested by reviewers on this patch >>> --- >>> drivers/accel/qda/Makefile | 2 + >>> drivers/accel/qda/qda_drv.c | 4 + >>> drivers/accel/qda/qda_drv.h | 4 + >>> drivers/accel/qda/qda_gem.c | 134 ++++++++++++++++++ >>> drivers/accel/qda/qda_gem.h | 52 +++++++ >>> drivers/accel/qda/qda_memory_dma.c | 82 +++++++++++ >>> drivers/accel/qda/qda_memory_dma.h | 17 +++ >>> drivers/accel/qda/qda_memory_manager.c | 239 ++++++++++++++++++++++++++++++++- >>> drivers/accel/qda/qda_memory_manager.h | 30 +++++ >>> 9 files changed, 559 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile >>> index b658dad35fee..a46ddceecfc5 100644 >>> --- a/drivers/accel/qda/Makefile >>> +++ b/drivers/accel/qda/Makefile >>> @@ -8,7 +8,9 @@ obj-$(CONFIG_DRM_ACCEL_QDA) := qda.o >>> qda-y := \ >>> qda_cb.o \ >>> qda_drv.o \ >>> + qda_gem.o \ >>> qda_ioctl.o \ >>> + qda_memory_dma.o \ >>> qda_memory_manager.o \ >>> qda_rpmsg.o >>> >>> diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c >>> index e1fd8bfa12d7..2b14dab95507 100644 >>> --- a/drivers/accel/qda/qda_drv.c >>> +++ b/drivers/accel/qda/qda_drv.c >>> @@ -21,6 +21,7 @@ static int qda_open(struct drm_device *dev, struct drm_file *file) >>> if (!qda_file_priv) >>> return -ENOMEM; >>> >>> + qda_file_priv->pid = current->pid; >>> qda_file_priv->qda_dev = qda_dev_from_drm(dev); >>> file->driver_priv = qda_file_priv; >>> >>> @@ -31,6 +32,9 @@ static void qda_postclose(struct drm_device *dev, struct drm_file *file) >>> { >>> struct qda_file_priv *qda_file_priv = file->driver_priv; >>> >>> + if (qda_file_priv->assigned_iommu_dev) >>> + qda_memory_manager_release_device(qda_file_priv->assigned_iommu_dev); >>> + >>> kfree(qda_file_priv); >>> file->driver_priv = NULL; >>> } >>> diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h >>> index 690a833d732b..2fe58f3efec0 100644 >>> --- a/drivers/accel/qda/qda_drv.h >>> +++ b/drivers/accel/qda/qda_drv.h >>> @@ -24,6 +24,10 @@ >>> struct qda_file_priv { >>> /** @qda_dev: Back-pointer to device structure */ >>> struct qda_dev *qda_dev; >>> + /** @assigned_iommu_dev: IOMMU device assigned to this process */ >>> + struct qda_iommu_device *assigned_iommu_dev; >>> + /** @pid: Process ID for tracking */ >>> + pid_t pid; >>> }; >>> >>> /** >>> diff --git a/drivers/accel/qda/qda_gem.c b/drivers/accel/qda/qda_gem.c >>> new file mode 100644 >>> index 000000000000..66e78013a726 >>> --- /dev/null >>> +++ b/drivers/accel/qda/qda_gem.c >>> @@ -0,0 +1,134 @@ >>> +// SPDX-License-Identifier: GPL-2.0-only >>> +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include "qda_drv.h" >>> +#include "qda_gem.h" >>> +#include "qda_memory_manager.h" >>> +#include "qda_memory_dma.h" >>> + >>> +/** >>> + * qda_gem_free_object() - Free a GEM object and its associated resources >>> + * @gem_obj: DRM GEM object to free >>> + */ >>> +void qda_gem_free_object(struct drm_gem_object *gem_obj) >>> +{ >>> + struct qda_gem_obj *qda_gem_obj = to_qda_gem_obj(gem_obj); >>> + struct qda_dev *qdev = qda_dev_from_drm(gem_obj->dev); >>> + >>> + if (qda_gem_obj->virt && qdev->iommu_mgr) >>> + qda_memory_manager_free(qdev->iommu_mgr, qda_gem_obj); >>> + >>> + drm_gem_object_release(gem_obj); >>> + kfree(qda_gem_obj); >>> +} >>> + >>> +/** >>> + * qda_gem_mmap_obj() - Map a GEM object into userspace >>> + * @drm_obj: DRM GEM object to map >>> + * @vma: Virtual memory area to map into >>> + * >>> + * Return: 0 on success, negative error code on failure >>> + */ >>> +int qda_gem_mmap_obj(struct drm_gem_object *drm_obj, struct vm_area_struct *vma) >>> +{ >>> + struct qda_gem_obj *qda_gem_obj = to_qda_gem_obj(drm_obj); >>> + int ret; >>> + >>> + /* The fake offset is only used to find the object, not to index it */ >>> + vma->vm_pgoff = 0; >>> + >>> + ret = qda_dma_mmap(qda_gem_obj, vma); >>> + if (ret) >>> + return ret; >>> + >>> + vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); >>> + >>> + return 0; >>> +} >>> + >>> +static const struct drm_gem_object_funcs qda_gem_object_funcs = { >>> + .free = qda_gem_free_object, >>> + .mmap = qda_gem_mmap_obj, >>> +}; >>> + >>> +/** >>> + * qda_gem_alloc_object() - Allocate a new QDA GEM object >>> + * @drm_dev: DRM device >>> + * @aligned_size: Size of the object in bytes (must be page-aligned) >>> + * >>> + * Return: Pointer to the new GEM object, or ERR_PTR on failure >>> + */ >>> +struct qda_gem_obj *qda_gem_alloc_object(struct drm_device *drm_dev, size_t aligned_size) >>> +{ >>> + struct qda_gem_obj *qda_gem_obj; >>> + int ret; >>> + >>> + qda_gem_obj = kzalloc_obj(*qda_gem_obj); >>> + if (!qda_gem_obj) >>> + return ERR_PTR(-ENOMEM); >>> + >>> + ret = drm_gem_object_init(drm_dev, &qda_gem_obj->base, aligned_size); >>> + if (ret) { >>> + kfree(qda_gem_obj); >>> + return ERR_PTR(ret); >>> + } >>> + >>> + qda_gem_obj->base.funcs = &qda_gem_object_funcs; >>> + qda_gem_obj->size = aligned_size; >>> + >>> + return qda_gem_obj; >>> +} >>> + >>> +void qda_gem_cleanup_object(struct qda_gem_obj *qda_gem_obj) >>> +{ >>> + drm_gem_object_release(&qda_gem_obj->base); >>> + kfree(qda_gem_obj); >>> +} >>> + >>> +int qda_gem_create_handle(struct drm_file *file_priv, struct drm_gem_object *gem_obj, u32 *handle) >>> +{ >>> + int ret; >>> + >>> + ret = drm_gem_handle_create(file_priv, gem_obj, handle); >>> + drm_gem_object_put(gem_obj); >>> + >>> + return ret; >>> +} >>> + >>> +/** >>> + * qda_gem_create_object() - Allocate and initialize a GEM object with DMA backing >>> + * @drm_dev: DRM device >>> + * @iommu_mgr: Memory manager to use for DMA allocation >>> + * @size: Requested size in bytes >>> + * @file_priv: DRM file private data for process association >>> + * >>> + * Return: Pointer to the base DRM GEM object on success, ERR_PTR on failure >>> + */ >>> +struct drm_gem_object *qda_gem_create_object(struct drm_device *drm_dev, >>> + struct qda_memory_manager *iommu_mgr, size_t size, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_gem_obj *qda_gem_obj; >>> + size_t aligned_size; >>> + int ret; >>> + >>> + aligned_size = PAGE_ALIGN(size); >>> + if (!aligned_size) >>> + return ERR_PTR(-EINVAL); >>> + >>> + qda_gem_obj = qda_gem_alloc_object(drm_dev, aligned_size); >>> + if (IS_ERR(qda_gem_obj)) >>> + return ERR_CAST(qda_gem_obj); >>> + >>> + ret = qda_memory_manager_alloc(iommu_mgr, qda_gem_obj, file_priv); >>> + if (ret) { >>> + qda_gem_cleanup_object(qda_gem_obj); >>> + return ERR_PTR(ret); >>> + } >>> + >>> + return &qda_gem_obj->base; >>> +} >>> diff --git a/drivers/accel/qda/qda_gem.h b/drivers/accel/qda/qda_gem.h >>> new file mode 100644 >>> index 000000000000..afd7c9b49549 >>> --- /dev/null >>> +++ b/drivers/accel/qda/qda_gem.h >>> @@ -0,0 +1,52 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> +/* >>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >>> + */ >>> +#ifndef __QDA_GEM_H__ >>> +#define __QDA_GEM_H__ >>> + >>> +#include >>> +#include >>> +#include >>> +#include "qda_memory_manager.h" >>> + >>> +/** >>> + * struct qda_gem_obj - QDA GEM buffer object >>> + * >>> + * Represents a GEM buffer object that can be allocated by the driver >>> + * or imported from another driver via DMA-BUF. >>> + */ >>> +struct qda_gem_obj { >>> + /** @base: DRM GEM object base — must be first member */ >>> + struct drm_gem_object base; >>> + /** @iommu_dev: IOMMU context bank device that performed the allocation */ >>> + struct qda_iommu_device *iommu_dev; >>> + /** @virt: Kernel virtual address of the allocated DMA memory */ >>> + void *virt; >>> + /** @dma_addr: DMA address (with SID encoded in upper 32 bits) */ >>> + dma_addr_t dma_addr; >>> + /** @size: Size of the buffer in bytes */ >>> + size_t size; >>> +}; >>> + >>> +/** >>> + * to_qda_gem_obj - Cast a drm_gem_object pointer to qda_gem_obj >>> + * @gem_obj: Pointer to the embedded drm_gem_object >>> + */ >>> +#define to_qda_gem_obj(gem_obj) container_of(gem_obj, struct qda_gem_obj, base) >>> + >>> +/* GEM object lifecycle */ >>> +struct drm_gem_object *qda_gem_create_object(struct drm_device *drm_dev, >>> + struct qda_memory_manager *iommu_mgr, >>> + size_t size, struct drm_file *file_priv); >>> +void qda_gem_free_object(struct drm_gem_object *gem_obj); >>> +int qda_gem_mmap_obj(struct drm_gem_object *gem_obj, struct vm_area_struct *vma); >>> + >>> +/* Internal helpers (also used by PRIME import) */ >>> +struct qda_gem_obj *qda_gem_alloc_object(struct drm_device *drm_dev, size_t aligned_size); >>> +void qda_gem_cleanup_object(struct qda_gem_obj *qda_gem_obj); >>> + >>> +/* Utility functions */ >>> +int qda_gem_create_handle(struct drm_file *file_priv, struct drm_gem_object *gem_obj, u32 *handle); >>> + >>> +#endif /* __QDA_GEM_H__ */ >>> diff --git a/drivers/accel/qda/qda_memory_dma.c b/drivers/accel/qda/qda_memory_dma.c >>> new file mode 100644 >>> index 000000000000..7072ed8edf0b >>> --- /dev/null >>> +++ b/drivers/accel/qda/qda_memory_dma.c >>> @@ -0,0 +1,82 @@ >>> +// SPDX-License-Identifier: GPL-2.0-only >>> +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >>> +#include >>> +#include >>> +#include "qda_drv.h" >>> +#include "qda_gem.h" >>> +#include "qda_memory_dma.h" >>> + >>> +/* >>> + * The DSP identifies the IOMMU context bank from the upper bits of the address, >>> + * so the stream ID is folded into every address handed to it. The DMA API only >>> + * ever sees the plain 32-bit address, which is why the context bank devices are >>> + * created with a 32-bit DMA mask. >>> + */ >>> +static dma_addr_t get_actual_dma_addr(struct qda_gem_obj *gem_obj) >>> +{ >>> + return gem_obj->dma_addr - ((u64)gem_obj->iommu_dev->sid << 32); >>> +} >>> + >>> +static void setup_gem_object(struct qda_gem_obj *gem_obj, void *virt, >>> + dma_addr_t dma_addr, struct qda_iommu_device *iommu_dev) >>> +{ >>> + gem_obj->virt = virt; >>> + gem_obj->dma_addr = dma_addr; >>> + gem_obj->iommu_dev = iommu_dev; >>> +} >>> + >>> +static void cleanup_gem_object_fields(struct qda_gem_obj *gem_obj) >>> +{ >>> + gem_obj->virt = NULL; >>> + gem_obj->dma_addr = 0; >>> + gem_obj->iommu_dev = NULL; >>> +} >>> + >>> +/** >>> + * qda_dma_alloc() - Allocate DMA coherent memory for a GEM object >>> + * @iommu_dev: Pointer to the QDA IOMMU device structure >>> + * @gem_obj: Pointer to GEM object to allocate memory for >>> + * @size: Size of memory to allocate in bytes >>> + * >>> + * Return: 0 on success, negative error code on failure >>> + */ >>> +int qda_dma_alloc(struct qda_iommu_device *iommu_dev, >>> + struct qda_gem_obj *gem_obj, size_t size) >>> +{ >>> + dma_addr_t dma_addr; >>> + void *virt; >>> + >>> + virt = dma_alloc_coherent(iommu_dev->dev, size, &dma_addr, GFP_KERNEL); >>> + if (!virt) >>> + return -ENOMEM; >>> + >>> + dma_addr += ((u64)iommu_dev->sid << 32); >>> + setup_gem_object(gem_obj, virt, dma_addr, iommu_dev); >>> + >>> + return 0; >>> +} >>> + >>> +/** >>> + * qda_dma_free() - Free DMA coherent memory for a GEM object >>> + * @gem_obj: Pointer to GEM object to free memory for >>> + */ >>> +void qda_dma_free(struct qda_gem_obj *gem_obj) >>> +{ >>> + dma_free_coherent(gem_obj->iommu_dev->dev, gem_obj->size, >>> + gem_obj->virt, get_actual_dma_addr(gem_obj)); >>> + >>> + cleanup_gem_object_fields(gem_obj); >>> +} >>> + >>> +/** >>> + * qda_dma_mmap() - Map DMA memory into userspace >>> + * @gem_obj: Pointer to GEM object containing DMA memory >>> + * @vma: Virtual memory area to map into >>> + * >>> + * Return: 0 on success, negative error code on failure >>> + */ >>> +int qda_dma_mmap(struct qda_gem_obj *gem_obj, struct vm_area_struct *vma) >>> +{ >>> + return dma_mmap_coherent(gem_obj->iommu_dev->dev, vma, gem_obj->virt, >>> + get_actual_dma_addr(gem_obj), gem_obj->size); >>> +} >>> diff --git a/drivers/accel/qda/qda_memory_dma.h b/drivers/accel/qda/qda_memory_dma.h >>> new file mode 100644 >>> index 000000000000..99352a99dc33 >>> --- /dev/null >>> +++ b/drivers/accel/qda/qda_memory_dma.h >>> @@ -0,0 +1,17 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> +/* >>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >>> + */ >>> + >>> +#ifndef __QDA_MEMORY_DMA_H__ >>> +#define __QDA_MEMORY_DMA_H__ >>> + >>> +#include >>> +#include "qda_memory_manager.h" >>> + >>> +int qda_dma_alloc(struct qda_iommu_device *iommu_dev, >>> + struct qda_gem_obj *gem_obj, size_t size); >>> +void qda_dma_free(struct qda_gem_obj *gem_obj); >>> +int qda_dma_mmap(struct qda_gem_obj *gem_obj, struct vm_area_struct *vma); >>> + >>> +#endif /* __QDA_MEMORY_DMA_H__ */ >>> diff --git a/drivers/accel/qda/qda_memory_manager.c b/drivers/accel/qda/qda_memory_manager.c >>> index b1a80ee77c35..d47c7419e11d 100644 >>> --- a/drivers/accel/qda/qda_memory_manager.c >>> +++ b/drivers/accel/qda/qda_memory_manager.c >>> @@ -1,14 +1,26 @@ >>> // SPDX-License-Identifier: GPL-2.0-only >>> // Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. >>> >>> +#include >>> #include >>> +#include >>> +#include >>> +#include >>> #include "qda_drv.h" >>> +#include "qda_gem.h" >>> #include "qda_memory_manager.h" >>> +#include "qda_memory_dma.h" >>> + >>> +static void iommu_device_free(struct kref *ref) >>> +{ >>> + kfree(container_of(ref, struct qda_iommu_device, ref)); >>> +} >>> >>> static void cleanup_all_memory_devices(struct qda_memory_manager *mem_mgr) >>> { >>> int i; >>> >>> + mutex_lock(&mem_mgr->process_assignment_lock); >>> for (i = 0; i < mem_mgr->num_devices; i++) { >>> struct qda_iommu_device *iommu_dev = mem_mgr->devices[i]; >>> >>> @@ -16,9 +28,215 @@ static void cleanup_all_memory_devices(struct qda_memory_manager *mem_mgr) >>> continue; >>> >>> mem_mgr->devices[i] = NULL; >>> - kfree(iommu_dev); >>> + kref_put(&iommu_dev->ref, iommu_device_free); >>> } >>> mem_mgr->num_devices = 0; >>> + mutex_unlock(&mem_mgr->process_assignment_lock); >>> +} >>> + >>> +static void init_iommu_device_fields(struct qda_iommu_device *iommu_dev) >>> +{ >>> + spin_lock_init(&iommu_dev->lock); >>> + refcount_set(&iommu_dev->users, 0); >>> + kref_init(&iommu_dev->ref); >>> + iommu_dev->assigned_pid = 0; >>> + iommu_dev->assigned_file_priv = NULL; >>> +} >>> + >>> +static struct qda_iommu_device *find_device_for_pid(struct qda_memory_manager *mem_mgr, >>> + pid_t pid) >>> +{ >>> + struct qda_iommu_device *found_dev = NULL; >>> + unsigned long flags; >>> + int i; >>> + >>> + for (i = 0; i < mem_mgr->num_devices; i++) { >>> + struct qda_iommu_device *iommu_dev = mem_mgr->devices[i]; >>> + >>> + if (!iommu_dev) >>> + continue; >>> + >>> + spin_lock_irqsave(&iommu_dev->lock, flags); >>> + if (iommu_dev->assigned_pid == pid) { >>> + found_dev = iommu_dev; >>> + refcount_inc(&found_dev->users); >>> + kref_get(&found_dev->ref); >>> + spin_unlock_irqrestore(&iommu_dev->lock, flags); >>> + break; >>> + } >>> + spin_unlock_irqrestore(&iommu_dev->lock, flags); >>> + } >>> + >>> + return found_dev; >>> +} >>> + >>> +static struct qda_iommu_device *assign_available_device_to_pid(struct qda_memory_manager *mem_mgr, >>> + pid_t pid, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_iommu_device *selected_dev = NULL; >>> + unsigned long flags; >>> + int i; >>> + >>> + for (i = 0; i < mem_mgr->num_devices; i++) { >>> + struct qda_iommu_device *iommu_dev = mem_mgr->devices[i]; >>> + >>> + if (!iommu_dev) >>> + continue; >>> + >>> + spin_lock_irqsave(&iommu_dev->lock, flags); >>> + if (iommu_dev->assigned_pid == 0) { >>> + iommu_dev->assigned_pid = pid; >>> + iommu_dev->assigned_file_priv = file_priv; >>> + selected_dev = iommu_dev; >>> + refcount_set(&selected_dev->users, 1); >>> + kref_get(&selected_dev->ref); >>> + spin_unlock_irqrestore(&iommu_dev->lock, flags); >>> + break; >>> + } >>> + spin_unlock_irqrestore(&iommu_dev->lock, flags); >>> + } >>> + >>> + return selected_dev; >>> +} >>> + >>> +static struct qda_iommu_device *get_process_iommu_device(struct qda_memory_manager *mem_mgr, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_file_priv *qda_priv; >>> + >>> + if (!file_priv || !file_priv->driver_priv) >>> + return NULL; >>> + >>> + qda_priv = (struct qda_file_priv *)file_priv->driver_priv; >>> + return qda_priv->assigned_iommu_dev; >>> +} >>> + >>> +/** >>> + * qda_memory_manager_assign_device() - Assign an IOMMU device to a process >>> + * @mem_mgr: Pointer to memory manager >>> + * @file_priv: DRM file private data for process association >>> + * >>> + * On success the caller owns a reference on the device and must release it >>> + * with qda_memory_manager_release_device(). >>> + * >>> + * Return: 0 on success, negative error code on failure >>> + */ >>> +int qda_memory_manager_assign_device(struct qda_memory_manager *mem_mgr, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_file_priv *qda_priv; >>> + struct qda_iommu_device *selected_dev = NULL; >>> + int ret = 0; >>> + pid_t current_pid; >>> + >>> + if (!file_priv || !file_priv->driver_priv) >>> + return -EINVAL; >>> + >>> + qda_priv = (struct qda_file_priv *)file_priv->driver_priv; >>> + current_pid = qda_priv->pid; >>> + >>> + mutex_lock(&mem_mgr->process_assignment_lock); >>> + >>> + if (qda_priv->assigned_iommu_dev) { >>> + ret = 0; >>> + goto unlock_and_return; >>> + } >>> + >>> + selected_dev = find_device_for_pid(mem_mgr, current_pid); >>> + >>> + if (selected_dev) { >>> + qda_priv->assigned_iommu_dev = selected_dev; >>> + goto unlock_and_return; >>> + } >>> + >>> + selected_dev = assign_available_device_to_pid(mem_mgr, current_pid, file_priv); >>> + >>> + if (!selected_dev) { >>> + drm_dbg_driver(file_priv->minor->dev, "No context bank available for PID %d\n", >>> + current_pid); >>> + ret = -EBUSY; >>> + goto unlock_and_return; >>> + } >>> + >>> + qda_priv->assigned_iommu_dev = selected_dev; >>> + >>> +unlock_and_return: >>> + mutex_unlock(&mem_mgr->process_assignment_lock); >>> + >>> + return ret; >>> +} >>> + >>> +/** >>> + * qda_memory_manager_release_device() - Release a process assignment >>> + * @iommu_dev: Device previously obtained from qda_memory_manager_assign_device() >>> + * >>> + * Drops the caller's reference. Once the last process using the device is >>> + * gone the assignment is cleared so the device can serve another process. >>> + */ >>> +void qda_memory_manager_release_device(struct qda_iommu_device *iommu_dev) >>> +{ >>> + unsigned long flags; >>> + >>> + if (refcount_dec_and_test(&iommu_dev->users)) { >>> + spin_lock_irqsave(&iommu_dev->lock, flags); >>> + iommu_dev->assigned_pid = 0; >>> + iommu_dev->assigned_file_priv = NULL; >>> + spin_unlock_irqrestore(&iommu_dev->lock, flags); >>> + } >>> + >>> + kref_put(&iommu_dev->ref, iommu_device_free); >>> +} >>> + >>> +static struct qda_iommu_device *get_or_assign_iommu_device(struct qda_memory_manager *mem_mgr, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_iommu_device *iommu_dev; >>> + int ret; >>> + >>> + iommu_dev = get_process_iommu_device(mem_mgr, file_priv); >>> + if (iommu_dev) >>> + return iommu_dev; >>> + >>> + ret = qda_memory_manager_assign_device(mem_mgr, file_priv); >>> + if (ret) >>> + return NULL; >>> + >>> + iommu_dev = get_process_iommu_device(mem_mgr, file_priv); >>> + if (iommu_dev) >>> + return iommu_dev; >>> + >>> + return NULL; >>> +} >>> + >>> +/** >>> + * qda_memory_manager_alloc() - Allocate memory for a GEM object >>> + * @mem_mgr: Pointer to memory manager >>> + * @gem_obj: Pointer to GEM object to allocate memory for >>> + * @file_priv: DRM file private data for process association >>> + * >>> + * Return: 0 on success, negative error code on failure >>> + */ >>> +int qda_memory_manager_alloc(struct qda_memory_manager *mem_mgr, struct qda_gem_obj *gem_obj, >>> + struct drm_file *file_priv) >>> +{ >>> + struct qda_iommu_device *selected_dev; >>> + >>> + selected_dev = get_or_assign_iommu_device(mem_mgr, file_priv); >>> + if (!selected_dev) >>> + return -EBUSY; >>> + >>> + return qda_dma_alloc(selected_dev, gem_obj, gem_obj->size); >>> +} >>> + >>> +/** >>> + * qda_memory_manager_free() - Free memory for a GEM object >>> + * @mem_mgr: Pointer to memory manager >>> + * @gem_obj: Pointer to GEM object to free memory for >>> + */ >>> +void qda_memory_manager_free(struct qda_memory_manager *mem_mgr, struct qda_gem_obj *gem_obj) >>> +{ >>> + qda_dma_free(gem_obj); >>> } >>> >>> /** >>> @@ -31,13 +249,21 @@ static void cleanup_all_memory_devices(struct qda_memory_manager *mem_mgr) >>> int qda_memory_manager_register_device(struct qda_memory_manager *mem_mgr, >>> struct qda_iommu_device *iommu_dev) >>> { >>> - if (mem_mgr->num_devices >= mem_mgr->max_devices) >>> - return -ENOSPC; >>> + int ret = 0; >>> >>> + mutex_lock(&mem_mgr->process_assignment_lock); >>> + if (mem_mgr->num_devices >= mem_mgr->max_devices) { >>> + ret = -ENOSPC; >>> + goto out; >>> + } >>> + >>> + init_iommu_device_fields(iommu_dev); >>> iommu_dev->id = mem_mgr->num_devices; >>> mem_mgr->devices[mem_mgr->num_devices++] = iommu_dev; >>> >>> - return 0; >>> +out: >>> + mutex_unlock(&mem_mgr->process_assignment_lock); >>> + return ret; >>> } >>> >>> /** >>> @@ -52,14 +278,16 @@ void qda_memory_manager_unregister_device(struct qda_memory_manager *mem_mgr, >>> { >>> int i; >>> >>> + mutex_lock(&mem_mgr->process_assignment_lock); >>> for (i = 0; i < mem_mgr->num_devices; i++) { >>> if (mem_mgr->devices[i] == iommu_dev) { >>> mem_mgr->devices[i] = NULL; >>> break; >>> } >>> } >>> + mutex_unlock(&mem_mgr->process_assignment_lock); >>> >>> - kfree(iommu_dev); >>> + kref_put(&iommu_dev->ref, iommu_device_free); >>> } >>> >>> /** >>> @@ -80,6 +308,7 @@ int qda_memory_manager_init(struct qda_memory_manager *mem_mgr, int max_devices) >>> >>> mem_mgr->num_devices = 0; >>> mem_mgr->max_devices = max_devices; >>> + mutex_init(&mem_mgr->process_assignment_lock); >>> >>> return 0; >>> } >>> diff --git a/drivers/accel/qda/qda_memory_manager.h b/drivers/accel/qda/qda_memory_manager.h >>> index 7e38c8a18284..0949c0c213f6 100644 >>> --- a/drivers/accel/qda/qda_memory_manager.h >>> +++ b/drivers/accel/qda/qda_memory_manager.h >>> @@ -7,25 +7,44 @@ >>> #define __QDA_MEMORY_MANAGER_H__ >>> >>> #include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> >>> /* Forward declarations */ >>> struct qda_dev; >>> +struct qda_gem_obj; >>> >>> /** >>> * struct qda_iommu_device - IOMMU device instance for memory management >>> * >>> * Represents a single IOMMU-enabled device managed by the memory manager. >>> * Each device can be assigned to a specific process session. >>> + * >>> + * The object outlives its registration: open files keep a reference through >>> + * @ref, so a device can be unregistered while a process still holds it. >>> */ >>> struct qda_iommu_device { >>> /** @dev: Pointer to the underlying device */ >>> struct device *dev; >>> /** @qdev: Back-pointer to the parent QDA device */ >>> struct qda_dev *qdev; >>> + /** @assigned_file_priv: DRM file private data for the assigned process */ >>> + struct drm_file *assigned_file_priv; >>> /** @id: Unique identifier assigned by the memory manager */ >>> u32 id; >>> /** @sid: Stream ID for IOMMU transactions */ >>> u32 sid; >>> + /** @assigned_pid: Process ID of the process assigned to this device */ >>> + pid_t assigned_pid; >>> + /** @users: Number of open files sharing this device */ >>> + refcount_t users; >>> + /** @ref: Reference count controlling when the object is freed */ >>> + struct kref ref; >>> + /** @lock: Spinlock protecting concurrent access to device */ >>> + spinlock_t lock; >>> }; >>> >>> /** >>> @@ -42,6 +61,8 @@ struct qda_memory_manager { >>> int num_devices; >>> /** @max_devices: Capacity of the @devices array */ >>> int max_devices; >>> + /** @process_assignment_lock: Mutex protecting process-to-device assignments */ >>> + struct mutex process_assignment_lock; >>> }; >>> >>> int qda_memory_manager_init(struct qda_memory_manager *mem_mgr, int max_devices); >>> @@ -51,5 +72,14 @@ int qda_memory_manager_register_device(struct qda_memory_manager *mem_mgr, >>> struct qda_iommu_device *iommu_dev); >>> void qda_memory_manager_unregister_device(struct qda_memory_manager *mem_mgr, >>> struct qda_iommu_device *iommu_dev); >>> +int qda_memory_manager_assign_device(struct qda_memory_manager *mem_mgr, >>> + struct drm_file *file_priv); >>> +void qda_memory_manager_release_device(struct qda_iommu_device *iommu_dev); >>> + >>> +int qda_memory_manager_alloc(struct qda_memory_manager *mem_mgr, >>> + struct qda_gem_obj *gem_obj, >>> + struct drm_file *file_priv); >>> +void qda_memory_manager_free(struct qda_memory_manager *mem_mgr, >>> + struct qda_gem_obj *gem_obj); >>> >>> #endif /* __QDA_MEMORY_MANAGER_H__ */ >>> >>