On 8/17/26 06:47, Ekansh Gupta wrote: > Introduce DMA-coherent buffer management for the QDA driver, wiring > together the GEM subsystem, the IOMMU memory manager, and a DMA > allocation backend. > > qda_gem.c / qda_gem.h > Implements the GEM object lifecycle for QDA buffers. 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. 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 <[email protected]> > --- > 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 <drm/drm_gem.h> > +#include <drm/drm_prime.h> > +#include <drm/drm_print.h> > +#include <linux/slab.h> > +#include <linux/dma-mapping.h> > +#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 <linux/dma-mapping.h> > +#include <drm/drm_device.h> > +#include <drm/drm_gem.h> > +#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 <linux/slab.h> > +#include <linux/dma-mapping.h> > +#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 <linux/dma-mapping.h> > +#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 <linux/refcount.h> > #include <linux/slab.h> > +#include <linux/spinlock.h> > +#include <drm/drm_file.h> > +#include <drm/drm_print.h> > #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 <linux/device.h> > +#include <linux/kref.h> > +#include <linux/mutex.h> > +#include <linux/refcount.h> > +#include <linux/spinlock.h> > +#include <drm/drm_file.h> > > /* 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__ */ >
