[PATCH] vfio: Add "#ifdef CONFIG_MMU" for vma operations

[PATCH] vfio: Add "#ifdef CONFIG_MMU" for vma operations

[Cai Huoqing]

Add "#ifdef CONFIG_MMU",
because vma mmap and vm_operations_struct depend on MMU

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
---
 drivers/vfio/pci/vfio_pci.c | 4 ++++
 drivers/vfio/vfio.c         | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 318864d52837..d49b27f15a3f 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1559,6 +1559,7 @@ static int __vfio_pci_add_vma(struct vfio_pci_device *vdev,
  * Zap mmaps on open so that we can fault them in on access and therefore
  * our vma_list only tracks mappings accessed since last zap.
  */
+#ifdef CONFIG_MMU
 static void vfio_pci_mmap_open(struct vm_area_struct *vma)
 {
 	zap_vma_ptes(vma, vma->vm_start, vma->vm_end - vma->vm_start);
@@ -1701,6 +1702,7 @@ static int vfio_pci_mmap(struct vfio_device *core_vdev, struct vm_area_struct *v
 
 	return 0;
 }
+#endif /* CONFIG_MMU */
 
 static void vfio_pci_request(struct vfio_device *core_vdev, unsigned int count)
 {
@@ -1875,7 +1877,9 @@ static const struct vfio_device_ops vfio_pci_ops = {
 	.ioctl		= vfio_pci_ioctl,
 	.read		= vfio_pci_read,
 	.write		= vfio_pci_write,
+#ifdef CONFIG_MMU
 	.mmap		= vfio_pci_mmap,
+#endif /* CONFIG_MMU */
 	.request	= vfio_pci_request,
 	.match		= vfio_pci_match,
 };
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 02cc51ce6891..2fb2de8d4d13 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1182,6 +1182,7 @@ static ssize_t vfio_fops_write(struct file *filep, const char __user *buf,
 	return ret;
 }
 
+#ifdef CONFIG_MMU
 static int vfio_fops_mmap(struct file *filep, struct vm_area_struct *vma)
 {
 	struct vfio_container *container = filep->private_data;
@@ -1194,6 +1195,7 @@ static int vfio_fops_mmap(struct file *filep, struct vm_area_struct *vma)
 
 	return ret;
 }
+#endif /* CONFIG_MMU */
 
 static const struct file_operations vfio_fops = {
 	.owner		= THIS_MODULE,
@@ -1203,7 +1205,9 @@ static const struct file_operations vfio_fops = {
 	.write		= vfio_fops_write,
 	.unlocked_ioctl	= vfio_fops_unl_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
+#ifdef CONFIG_MMU
 	.mmap		= vfio_fops_mmap,
+#endif /* CONFIG_MMU */
 };
 
 /**
@@ -1601,6 +1605,7 @@ static ssize_t vfio_device_fops_write(struct file *filep,
 	return device->ops->write(device, buf, count, ppos);
 }
 
+#ifdef CONFIG_MMU
 static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
 {
 	struct vfio_device *device = filep->private_data;
@@ -1610,6 +1615,7 @@ static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
 
 	return device->ops->mmap(device, vma);
 }
+#endif /* CONFIG_MMU */
 
 static const struct file_operations vfio_device_fops = {
 	.owner		= THIS_MODULE,
@@ -1618,7 +1624,9 @@ static const struct file_operations vfio_device_fops = {
 	.write		= vfio_device_fops_write,
 	.unlocked_ioctl	= vfio_device_fops_unl_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
+#ifdef CONFIG_MMU
 	.mmap		= vfio_device_fops_mmap,
+#endif /* CONFIG_MMU */
 };
 
 /**
-- 
2.25.1

Re: [PATCH] vfio: Add "#ifdef CONFIG_MMU" for vma operations

[Cornelia Huck]

On Tue, Jul 27 2021, Cai Huoqing <caihuoqing@baidu.com> wrote:

> Add "#ifdef CONFIG_MMU",
> because vma mmap and vm_operations_struct depend on MMU

vfio_pci already depends on MMU -- what problems are you trying to fix?

>
> Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
> ---
>  drivers/vfio/pci/vfio_pci.c | 4 ++++
>  drivers/vfio/vfio.c         | 8 ++++++++
>  2 files changed, 12 insertions(+)

Re: [PATCH] vfio: Add "#ifdef CONFIG_MMU" for vma operations

[Alex Williamson]

On Tue, 27 Jul 2021 18:35:14 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Tue, Jul 27 2021, Cai Huoqing <caihuoqing@baidu.com> wrote:
> 
> > Add "#ifdef CONFIG_MMU",
> > because vma mmap and vm_operations_struct depend on MMU  
> 
> vfio_pci already depends on MMU -- what problems are you trying to fix?

Exactly my question, we silenced the randconfig builds without
CONFIG_MMU in commit 2a55ca373501 ("vfio/pci: zap_vma_ptes() needs
MMU").  Surely there are prototypes for vma_area_struct regardless of
CONFIG_MMU and vfio-core having an mmap callback has no dependency on
vm_operations_struct.  Thanks,

Alex