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Date: Tue, 21 Nov 2023 15:40:16 +0800 From: Jason Wang <jasowang@...hat.com> To: Cindy Lu <lulu@...hat.com> Cc: mst@...hat.com, xieyongji@...edance.com, linux-kernel@...r.kernel.org, maxime.coquelin@...hat.com Subject: Re: [PATCH v2 2/5] vduse: Add file operation for mmap On Tue, Nov 21, 2023 at 3:31 PM Cindy Lu <lulu@...hat.com> wrote: > > Add the operation for mmap, The user space APP will > use this function to map the pages to userspace > > Signed-off-by: Cindy Lu <lulu@...hat.com> > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 79 ++++++++++++++++++++++++++++++ > 1 file changed, 79 insertions(+) > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > index 6209e2f00278..ccb30e98bab5 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -1376,6 +1376,83 @@ static struct vduse_dev *vduse_dev_get_from_minor(int minor) > return dev; > } > > +static vm_fault_t vduse_vm_fault(struct vm_fault *vmf) > +{ > + struct vduse_dev *dev = vmf->vma->vm_file->private_data; > + struct vm_area_struct *vma = vmf->vma; > + u16 index = vma->vm_pgoff; > + struct vduse_virtqueue *vq; > + struct vdpa_reconnect_info *info; > + > + /* index 0 page reserved for vduse status*/ > + if (index == 0) { > + info = &dev->reconnect_info; > + } else { > + /* index 1+vq_number page reserved for vduse vqs*/ > + vq = &dev->vqs[index - 1]; > + info = &vq->reconnect_info; > + } > + if (remap_pfn_range(vma, vmf->address & PAGE_MASK, > + PFN_DOWN(virt_to_phys((void *)info->vaddr)), > + PAGE_SIZE, vma->vm_page_prot)) > + return VM_FAULT_SIGBUS; > + return VM_FAULT_NOPAGE; > +} > + > +static const struct vm_operations_struct vduse_vm_ops = { > + .fault = vduse_vm_fault, > +}; > + > +static int vduse_dev_mmap(struct file *file, struct vm_area_struct *vma) > +{ > + struct vduse_dev *dev = file->private_data; > + struct vdpa_reconnect_info *info; > + unsigned long index = vma->vm_pgoff; > + struct vduse_virtqueue *vq; > + > + if (vma->vm_end - vma->vm_start != PAGE_SIZE) > + return -EINVAL; > + if ((vma->vm_flags & VM_SHARED) == 0) > + return -EINVAL; > + > + /*check if Userspace App map the page number larger than kernel allocated*/ > + if (index > dev->vq_num + 1) > + return -EINVAL; > + > + /* index 0 page reserved for vduse status*/ > + if (index == 0) { > + info = &dev->reconnect_info; > + } else { > + /* index 1+vq_number page reserved for vduse vqs*/ > + vq = &dev->vqs[index - 1]; > + info = &vq->reconnect_info; > + } > + /*check if map pages was allocated and inited by kernel */ > + if (info->vaddr == 0) > + return -EOPNOTSUPP; > + > + /* check if the address is page aligned, if not, > + * this address maybe damaged > + */ > + if (virt_to_phys((void *)info->vaddr) & (PAGE_SIZE - 1)) > + return -EINVAL; > + > + /* check if Userspace App mapped the correct size > + * the userspace App should map one page each time > + */ > + if (vma->vm_end - vma->vm_start != PAGE_SIZE) > + return -EOPNOTSUPP; > + /* VM_IO: set as a memory-mapped I/O region,This will for vq information > + * VM_PFNMAP: only need the pure PFN > + * VM_DONTEXPAND: do not need to use mremap() in this function > + * VM_DONTDUMP:Do not include in the core dump > + */ Instead of duplicating the semantic, you need to explain why it is needed. For example I don't see how the following is useful: VM_IO: the page is not backed by any I/O page VM_PFNMAP: we need map it to usespace for sure, for it's not a pure PFN VM_DONTDUMP: including this in core dump may help to debug the userspace process for sure Thanks > + vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); > + vma->vm_ops = &vduse_vm_ops; > + > + return 0; > +} > + > static int vduse_dev_open(struct inode *inode, struct file *file) > { > int ret; > @@ -1408,6 +1485,8 @@ static const struct file_operations vduse_dev_fops = { > .unlocked_ioctl = vduse_dev_ioctl, > .compat_ioctl = compat_ptr_ioctl, > .llseek = noop_llseek, > + .mmap = vduse_dev_mmap, > + > }; > > static struct vduse_dev *vduse_dev_create(void) > -- > 2.34.3 >
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