[PATCH v4 11/17] KVM: introduce a 'mmap' method for KVM devices

[Cédric Le Goater]

Some KVM devices will want to handle special mappings related to the
underlying HW. For instance, the XIVE interrupt controller of the
POWER9 processor has MMIO pages for thread interrupt management and
for interrupt source control that need to be exposed to the guest when
the OS has the required support.

Cc: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Cédric Le Goater <clg at kaod.org>
Reviewed-by: David Gibson <david at gibson.dropbear.id.au>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9d55c63db09b..831d963451d8 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1245,6 +1245,7 @@ struct kvm_device_ops {
 	int (*has_attr)(struct kvm_device *dev, struct kvm_device_attr *attr);
 	long (*ioctl)(struct kvm_device *dev, unsigned int ioctl,
 		      unsigned long arg);
+	int (*mmap)(struct kvm_device *dev, struct vm_area_struct *vma);
 };
 
 void kvm_device_get(struct kvm_device *dev);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f25aa98a94df..5e2fa5c7dd1a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2884,6 +2884,16 @@ static long kvm_vcpu_compat_ioctl(struct file *filp,
 }
 #endif
 
+static int kvm_device_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct kvm_device *dev = filp->private_data;
+
+	if (dev->ops->mmap)
+		return dev->ops->mmap(dev, vma);
+
+	return -ENODEV;
+}
+
 static int kvm_device_ioctl_attr(struct kvm_device *dev,
 				 int (*accessor)(struct kvm_device *dev,
 						 struct kvm_device_attr *attr),
@@ -2933,6 +2943,7 @@ static const struct file_operations kvm_device_fops = {
 	.unlocked_ioctl = kvm_device_ioctl,
 	.release = kvm_device_release,
 	KVM_COMPAT(kvm_device_ioctl),
+	.mmap = kvm_device_mmap,
 };
 
 struct kvm_device *kvm_device_from_filp(struct file *filp)
-- 
2.20.1