diff mbox series

[RFC,2/4] vduse: Add file operation for mmap

Message ID 20230628065919.54042-3-lulu@redhat.com
State New
Headers
Series reconnect support in vduse |

Commit Message

Cindy Lu June 28, 2023, 6:59 a.m. UTC 
  From: Your Name <you@example.com>

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@redhat.com>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 49 ++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

Comments

Jason Wang June 28, 2023, 8:08 a.m. UTC | #1 
On Wed, Jun 28, 2023 at 2:59 PM Cindy Lu <lulu@redhat.com> wrote:
>
> From: Your Name <you@example.com>
>
> Add the operation for mmap, The user space APP will
> use this function to map the pages to userspace

Please be specific in the log. E.g why and what the main goal for this mmap.

>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 49 ++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index f845dc46b1db..1b833bf0ae37 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1313,6 +1313,54 @@ 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 vdpa_reconnect_info *info;
> +       info = &dev->reconnect_info[index];
> +
> +       vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> +       if (remap_pfn_range(vma, vmf->address & PAGE_MASK, PFN_DOWN(info->addr),
> +                           PAGE_SIZE, vma->vm_page_prot))

I'm not sure if this can work e.g do we want to use separate pages for
each virtqueue (I think the answer is yes).

> +               return VM_FAULT_SIGBUS;
> +       return VM_FAULT_NOPAGE;
> +}
> +
> +static const struct vm_operations_struct vduse_vm_ops = {
> +       .fault = vduse_vm_fault,
> +};
> +
> +static int vduse_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;
> +
> +       if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> +               return -EINVAL;
> +       if ((vma->vm_flags & VM_SHARED) == 0)
> +               return -EINVAL;
> +
> +       if (index > 65535)
> +               return -EINVAL;
> +
> +       info = &dev->reconnect_info[index];
> +       if (info->addr & (PAGE_SIZE - 1))
> +               return -EINVAL;
> +       if (vma->vm_end - vma->vm_start != info->size) {
> +               return -ENOTSUPP;
> +       }

How can userspace know the correct size (info->size) here?

> +
> +       vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);

Why do you need VM_IO, VM_PFNMAP and VM_DONTDUMP here?

Thanks

> +       vma->vm_ops = &vduse_vm_ops;
> +
> +       return 0;
> +}
> +
>  static int vduse_dev_open(struct inode *inode, struct file *file)
>  {
>         int ret;
> @@ -1345,6 +1393,7 @@ static const struct file_operations vduse_dev_fops = {
>         .unlocked_ioctl = vduse_dev_ioctl,
>         .compat_ioctl   = compat_ptr_ioctl,
>         .llseek         = noop_llseek,
> +       .mmap           = vduse_mmap,
>  };
>
>  static struct vduse_dev *vduse_dev_create(void)
> --
> 2.34.3
>
Cindy Lu July 1, 2023, 9:23 a.m. UTC | #2 
On Wed, Jun 28, 2023 at 4:08 PM Jason Wang <jasowang@redhat.com> wrote:
>
> On Wed, Jun 28, 2023 at 2:59 PM Cindy Lu <lulu@redhat.com> wrote:
> >
> > From: Your Name <you@example.com>
> >
> > Add the operation for mmap, The user space APP will
> > use this function to map the pages to userspace
>
> Please be specific in the log. E.g why and what the main goal for this mmap.
>
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > ---
> >  drivers/vdpa/vdpa_user/vduse_dev.c | 49 ++++++++++++++++++++++++++++++
> >  1 file changed, 49 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index f845dc46b1db..1b833bf0ae37 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -1313,6 +1313,54 @@ 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 vdpa_reconnect_info *info;
> > +       info = &dev->reconnect_info[index];
> > +
> > +       vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> > +       if (remap_pfn_range(vma, vmf->address & PAGE_MASK, PFN_DOWN(info->addr),
> > +                           PAGE_SIZE, vma->vm_page_prot))
>
> I'm not sure if this can work e.g do we want to use separate pages for
> each virtqueue (I think the answer is yes).
>
yes, this map the separate pages per vq, beads on my test this works
> > +               return VM_FAULT_SIGBUS;
> > +       return VM_FAULT_NOPAGE;
> > +}
> > +
> > +static const struct vm_operations_struct vduse_vm_ops = {
> > +       .fault = vduse_vm_fault,
> > +};
> > +
> > +static int vduse_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;
> > +
> > +       if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> > +               return -EINVAL;
> > +       if ((vma->vm_flags & VM_SHARED) == 0)
> > +               return -EINVAL;
> > +
> > +       if (index > 65535)
> > +               return -EINVAL;
> > +
> > +       info = &dev->reconnect_info[index];
> > +       if (info->addr & (PAGE_SIZE - 1))
> > +               return -EINVAL;
> > +       if (vma->vm_end - vma->vm_start != info->size) {
> > +               return -ENOTSUPP;
> > +       }
>
> How can userspace know the correct size (info->size) here?
>
I had hard code the size in userpace , I will add the new ioctl of get
the map size
Thanks
cindy
> > +
> > +       vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
>
> Why do you need VM_IO, VM_PFNMAP and VM_DONTDUMP here?
>
> Thanks
>
> > +       vma->vm_ops = &vduse_vm_ops;
> > +
> > +       return 0;
> > +}
> > +
> >  static int vduse_dev_open(struct inode *inode, struct file *file)
> >  {
> >         int ret;
> > @@ -1345,6 +1393,7 @@ static const struct file_operations vduse_dev_fops = {
> >         .unlocked_ioctl = vduse_dev_ioctl,
> >         .compat_ioctl   = compat_ptr_ioctl,
> >         .llseek         = noop_llseek,
> > +       .mmap           = vduse_mmap,
> >  };
> >
> >  static struct vduse_dev *vduse_dev_create(void)
> > --
> > 2.34.3
> >
>
Maxime Coquelin July 11, 2023, 2:18 p.m. UTC | #3 
On 6/28/23 08:59, Cindy Lu wrote:
> From: Your Name <you@example.com>
> 
> 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@redhat.com>
> ---
>   drivers/vdpa/vdpa_user/vduse_dev.c | 49 ++++++++++++++++++++++++++++++
>   1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index f845dc46b1db..1b833bf0ae37 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1313,6 +1313,54 @@ 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 vdpa_reconnect_info *info;
> +	info = &dev->reconnect_info[index];
> +
> +	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> +	if (remap_pfn_range(vma, vmf->address & PAGE_MASK, PFN_DOWN(info->addr),
> +			    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_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;
> +
> +	if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> +		return -EINVAL;
> +	if ((vma->vm_flags & VM_SHARED) == 0)
> +		return -EINVAL;
> +
> +	if (index > 65535)
> +		return -EINVAL;

You declare an array of 64 entries in patch 1, so it can overflow.

> +
> +	info = &dev->reconnect_info[index];
> +	if (info->addr & (PAGE_SIZE - 1))
> +		return -EINVAL;
> +	if (vma->vm_end - vma->vm_start != info->size) {
> +		return -ENOTSUPP;
> +	}
> +
> +	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;
> @@ -1345,6 +1393,7 @@ static const struct file_operations vduse_dev_fops = {
>   	.unlocked_ioctl	= vduse_dev_ioctl,
>   	.compat_ioctl	= compat_ptr_ioctl,
>   	.llseek		= noop_llseek,
> +	.mmap		= vduse_mmap,
>   };
>   
>   static struct vduse_dev *vduse_dev_create(void)
diff mbox series

Patch

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index f845dc46b1db..1b833bf0ae37 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -1313,6 +1313,54 @@  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 vdpa_reconnect_info *info;
+	info = &dev->reconnect_info[index];
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	if (remap_pfn_range(vma, vmf->address & PAGE_MASK, PFN_DOWN(info->addr),
+			    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_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;
+
+	if (vma->vm_end - vma->vm_start != PAGE_SIZE)
+		return -EINVAL;
+	if ((vma->vm_flags & VM_SHARED) == 0)
+		return -EINVAL;
+
+	if (index > 65535)
+		return -EINVAL;
+
+	info = &dev->reconnect_info[index];
+	if (info->addr & (PAGE_SIZE - 1))
+		return -EINVAL;
+	if (vma->vm_end - vma->vm_start != info->size) {
+		return -ENOTSUPP;
+	}
+
+	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;
@@ -1345,6 +1393,7 @@  static const struct file_operations vduse_dev_fops = {
 	.unlocked_ioctl	= vduse_dev_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
 	.llseek		= noop_llseek,
+	.mmap		= vduse_mmap,
 };
 
 static struct vduse_dev *vduse_dev_create(void)