diff mbox

[v2,1/4] KVM: device: add simple registration mechanism for kvm_device_ops

Message ID 1404225918-8903-1-git-send-email-will.deacon@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Will Deacon July 1, 2014, 2:45 p.m. UTC
kvm_ioctl_create_device currently has knowledge of all the device types
and their associated ops. This is fairly inflexible when adding support
for new in-kernel device emulations, so move what we currently have out
into a table, which can support dynamic registration of ops by new
drivers for virtual hardware.

I didn't try to port all current drivers over, as it's not always clear
which initialisation hook the ops should be registered from.

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Alex Williamson <Alex.Williamson@redhat.com>
Cc: Alex Graf <agraf@suse.de>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---

v1 -> v2: Added enum for KVM_DEV_TYPE* IDs, changed limits to ARRAY_SIZE,
          removed stray semicolon, had a crack at porting VFIO, included
	  Cornelia's s390 FLIC patch.

 include/linux/kvm_host.h |  1 +
 include/uapi/linux/kvm.h | 22 +++++++++++-----
 virt/kvm/kvm_main.c      | 65 ++++++++++++++++++++++++++++--------------------
 3 files changed, 55 insertions(+), 33 deletions(-)

Comments

Cornelia Huck July 2, 2014, 9:17 a.m. UTC | #1
On Tue,  1 Jul 2014 15:45:15 +0100
Will Deacon <will.deacon@arm.com> wrote:

> kvm_ioctl_create_device currently has knowledge of all the device types
> and their associated ops. This is fairly inflexible when adding support
> for new in-kernel device emulations, so move what we currently have out
> into a table, which can support dynamic registration of ops by new
> drivers for virtual hardware.
> 
> I didn't try to port all current drivers over, as it's not always clear
> which initialisation hook the ops should be registered from.

I think that last paragraph should rather go into a cover letter :)

> 
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Alex Williamson <Alex.Williamson@redhat.com>
> Cc: Alex Graf <agraf@suse.de>
> Cc: Gleb Natapov <gleb@kernel.org>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> ---
> 
> v1 -> v2: Added enum for KVM_DEV_TYPE* IDs, changed limits to ARRAY_SIZE,
>           removed stray semicolon, had a crack at porting VFIO, included
> 	  Cornelia's s390 FLIC patch.

...and the changelog as well (or keep changelogs for individual
patches).

> 
>  include/linux/kvm_host.h |  1 +
>  include/uapi/linux/kvm.h | 22 +++++++++++-----
>  virt/kvm/kvm_main.c      | 65 ++++++++++++++++++++++++++++--------------------
>  3 files changed, 55 insertions(+), 33 deletions(-)
> 

> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index e11d8f170a62..6875cc225dff 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -940,15 +940,25 @@ struct kvm_device_attr {
>  	__u64	addr;		/* userspace address of attr data */
>  };
> 
> -#define KVM_DEV_TYPE_FSL_MPIC_20	1
> -#define KVM_DEV_TYPE_FSL_MPIC_42	2
> -#define KVM_DEV_TYPE_XICS		3
> -#define KVM_DEV_TYPE_VFIO		4
>  #define  KVM_DEV_VFIO_GROUP			1
>  #define   KVM_DEV_VFIO_GROUP_ADD			1
>  #define   KVM_DEV_VFIO_GROUP_DEL			2
> -#define KVM_DEV_TYPE_ARM_VGIC_V2	5
> -#define KVM_DEV_TYPE_FLIC		6
> +
> +enum kvm_device_type {
> +	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
> +#define KVM_DEV_TYPE_FSL_MPIC_20	KVM_DEV_TYPE_FSL_MPIC_20
> +	KVM_DEV_TYPE_FSL_MPIC_42,
> +#define KVM_DEV_TYPE_FSL_MPIC_42	KVM_DEV_TYPE_FSL_MPIC_42
> +	KVM_DEV_TYPE_XICS,
> +#define KVM_DEV_TYPE_XICS		KVM_DEV_TYPE_XICS
> +	KVM_DEV_TYPE_VFIO,
> +#define KVM_DEV_TYPE_VFIO		KVM_DEV_TYPE_VFIO
> +	KVM_DEV_TYPE_ARM_VGIC_V2,
> +#define KVM_DEV_TYPE_ARM_VGIC_V2	KVM_DEV_TYPE_ARM_VGIC_V2
> +	KVM_DEV_TYPE_FLIC,
> +#define KVM_DEV_TYPE_FLIC		KVM_DEV_TYPE_FLIC
> +	KVM_DEV_TYPE_MAX,

Do you want to add the individual values to the enum? A removal of a
type would be an API break (so we should be safe against renumbering),
but it's sometimes helpful if one can get the numeric value at a glance.

> +};
> 
>  /*
>   * ioctls for VM fds

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Will Deacon July 2, 2014, 9:32 a.m. UTC | #2
On Wed, Jul 02, 2014 at 10:17:20AM +0100, Cornelia Huck wrote:
> On Tue,  1 Jul 2014 15:45:15 +0100
> Will Deacon <will.deacon@arm.com> wrote:
> 
> > kvm_ioctl_create_device currently has knowledge of all the device types
> > and their associated ops. This is fairly inflexible when adding support
> > for new in-kernel device emulations, so move what we currently have out
> > into a table, which can support dynamic registration of ops by new
> > drivers for virtual hardware.
> > 
> > I didn't try to port all current drivers over, as it's not always clear
> > which initialisation hook the ops should be registered from.
> 
> I think that last paragraph should rather go into a cover letter :)
> 
> > 
> > Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> > Cc: Alex Williamson <Alex.Williamson@redhat.com>
> > Cc: Alex Graf <agraf@suse.de>
> > Cc: Gleb Natapov <gleb@kernel.org>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Marc Zyngier <marc.zyngier@arm.com>
> > Cc: Christoffer Dall <christoffer.dall@linaro.org>
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> > ---
> > 
> > v1 -> v2: Added enum for KVM_DEV_TYPE* IDs, changed limits to ARRAY_SIZE,
> >           removed stray semicolon, had a crack at porting VFIO, included
> > 	  Cornelia's s390 FLIC patch.
> 
> ...and the changelog as well (or keep changelogs for individual
> patches).

Yeah... this has grown to be bigger than one patch now. I can include that
for v3.

> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index e11d8f170a62..6875cc225dff 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -940,15 +940,25 @@ struct kvm_device_attr {
> >  	__u64	addr;		/* userspace address of attr data */
> >  };
> > 
> > -#define KVM_DEV_TYPE_FSL_MPIC_20	1
> > -#define KVM_DEV_TYPE_FSL_MPIC_42	2
> > -#define KVM_DEV_TYPE_XICS		3
> > -#define KVM_DEV_TYPE_VFIO		4
> >  #define  KVM_DEV_VFIO_GROUP			1
> >  #define   KVM_DEV_VFIO_GROUP_ADD			1
> >  #define   KVM_DEV_VFIO_GROUP_DEL			2
> > -#define KVM_DEV_TYPE_ARM_VGIC_V2	5
> > -#define KVM_DEV_TYPE_FLIC		6
> > +
> > +enum kvm_device_type {
> > +	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
> > +#define KVM_DEV_TYPE_FSL_MPIC_20	KVM_DEV_TYPE_FSL_MPIC_20
> > +	KVM_DEV_TYPE_FSL_MPIC_42,
> > +#define KVM_DEV_TYPE_FSL_MPIC_42	KVM_DEV_TYPE_FSL_MPIC_42
> > +	KVM_DEV_TYPE_XICS,
> > +#define KVM_DEV_TYPE_XICS		KVM_DEV_TYPE_XICS
> > +	KVM_DEV_TYPE_VFIO,
> > +#define KVM_DEV_TYPE_VFIO		KVM_DEV_TYPE_VFIO
> > +	KVM_DEV_TYPE_ARM_VGIC_V2,
> > +#define KVM_DEV_TYPE_ARM_VGIC_V2	KVM_DEV_TYPE_ARM_VGIC_V2
> > +	KVM_DEV_TYPE_FLIC,
> > +#define KVM_DEV_TYPE_FLIC		KVM_DEV_TYPE_FLIC
> > +	KVM_DEV_TYPE_MAX,
> 
> Do you want to add the individual values to the enum? A removal of a
> type would be an API break (so we should be safe against renumbering),
> but it's sometimes helpful if one can get the numeric value at a glance.

Could do, but then I think the advantage of the enum is questionable over
the #defines, since you could just as easily have two entries in the enum
with the same ID value as forgetting to update a KVM_DEV_TYPE_MAX #define
(which was the reason for the enum in the first place).

So I'd be inclined to keep the patch as-is, unless you have really strong
objections?

Will
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Cornelia Huck July 2, 2014, 10:18 a.m. UTC | #3
On Wed, 2 Jul 2014 10:32:41 +0100
Will Deacon <will.deacon@arm.com> wrote:

> On Wed, Jul 02, 2014 at 10:17:20AM +0100, Cornelia Huck wrote:
> > On Tue,  1 Jul 2014 15:45:15 +0100
> > Will Deacon <will.deacon@arm.com> wrote:

> > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > > index e11d8f170a62..6875cc225dff 100644
> > > --- a/include/uapi/linux/kvm.h
> > > +++ b/include/uapi/linux/kvm.h
> > > @@ -940,15 +940,25 @@ struct kvm_device_attr {
> > >  	__u64	addr;		/* userspace address of attr data */
> > >  };
> > > 
> > > -#define KVM_DEV_TYPE_FSL_MPIC_20	1
> > > -#define KVM_DEV_TYPE_FSL_MPIC_42	2
> > > -#define KVM_DEV_TYPE_XICS		3
> > > -#define KVM_DEV_TYPE_VFIO		4
> > >  #define  KVM_DEV_VFIO_GROUP			1
> > >  #define   KVM_DEV_VFIO_GROUP_ADD			1
> > >  #define   KVM_DEV_VFIO_GROUP_DEL			2
> > > -#define KVM_DEV_TYPE_ARM_VGIC_V2	5
> > > -#define KVM_DEV_TYPE_FLIC		6
> > > +
> > > +enum kvm_device_type {
> > > +	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
> > > +#define KVM_DEV_TYPE_FSL_MPIC_20	KVM_DEV_TYPE_FSL_MPIC_20
> > > +	KVM_DEV_TYPE_FSL_MPIC_42,
> > > +#define KVM_DEV_TYPE_FSL_MPIC_42	KVM_DEV_TYPE_FSL_MPIC_42
> > > +	KVM_DEV_TYPE_XICS,
> > > +#define KVM_DEV_TYPE_XICS		KVM_DEV_TYPE_XICS
> > > +	KVM_DEV_TYPE_VFIO,
> > > +#define KVM_DEV_TYPE_VFIO		KVM_DEV_TYPE_VFIO
> > > +	KVM_DEV_TYPE_ARM_VGIC_V2,
> > > +#define KVM_DEV_TYPE_ARM_VGIC_V2	KVM_DEV_TYPE_ARM_VGIC_V2
> > > +	KVM_DEV_TYPE_FLIC,
> > > +#define KVM_DEV_TYPE_FLIC		KVM_DEV_TYPE_FLIC
> > > +	KVM_DEV_TYPE_MAX,
> > 
> > Do you want to add the individual values to the enum? A removal of a
> > type would be an API break (so we should be safe against renumbering),
> > but it's sometimes helpful if one can get the numeric value at a glance.
> 
> Could do, but then I think the advantage of the enum is questionable over
> the #defines, since you could just as easily have two entries in the enum
> with the same ID value as forgetting to update a KVM_DEV_TYPE_MAX #define
> (which was the reason for the enum in the first place).
> 
> So I'd be inclined to keep the patch as-is, unless you have really strong
> objections?

I don't really have a strong opinion on that, so

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

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Christoffer Dall July 31, 2014, 12:10 p.m. UTC | #4
On Tue, Jul 01, 2014 at 03:45:15PM +0100, Will Deacon wrote:
> kvm_ioctl_create_device currently has knowledge of all the device types
> and their associated ops. This is fairly inflexible when adding support
> for new in-kernel device emulations, so move what we currently have out
> into a table, which can support dynamic registration of ops by new
> drivers for virtual hardware.
> 
> I didn't try to port all current drivers over, as it's not always clear
> which initialisation hook the ops should be registered from.
> 
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Alex Williamson <Alex.Williamson@redhat.com>
> Cc: Alex Graf <agraf@suse.de>
> Cc: Gleb Natapov <gleb@kernel.org>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> ---
> 
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
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diff mbox

Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ec4e3bd83d47..b75faaf0d76d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1083,6 +1083,7 @@  struct kvm_device_ops {
 void kvm_device_get(struct kvm_device *dev);
 void kvm_device_put(struct kvm_device *dev);
 struct kvm_device *kvm_device_from_filp(struct file *filp);
+int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type);
 
 extern struct kvm_device_ops kvm_mpic_ops;
 extern struct kvm_device_ops kvm_xics_ops;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index e11d8f170a62..6875cc225dff 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -940,15 +940,25 @@  struct kvm_device_attr {
 	__u64	addr;		/* userspace address of attr data */
 };
 
-#define KVM_DEV_TYPE_FSL_MPIC_20	1
-#define KVM_DEV_TYPE_FSL_MPIC_42	2
-#define KVM_DEV_TYPE_XICS		3
-#define KVM_DEV_TYPE_VFIO		4
 #define  KVM_DEV_VFIO_GROUP			1
 #define   KVM_DEV_VFIO_GROUP_ADD			1
 #define   KVM_DEV_VFIO_GROUP_DEL			2
-#define KVM_DEV_TYPE_ARM_VGIC_V2	5
-#define KVM_DEV_TYPE_FLIC		6
+
+enum kvm_device_type {
+	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
+#define KVM_DEV_TYPE_FSL_MPIC_20	KVM_DEV_TYPE_FSL_MPIC_20
+	KVM_DEV_TYPE_FSL_MPIC_42,
+#define KVM_DEV_TYPE_FSL_MPIC_42	KVM_DEV_TYPE_FSL_MPIC_42
+	KVM_DEV_TYPE_XICS,
+#define KVM_DEV_TYPE_XICS		KVM_DEV_TYPE_XICS
+	KVM_DEV_TYPE_VFIO,
+#define KVM_DEV_TYPE_VFIO		KVM_DEV_TYPE_VFIO
+	KVM_DEV_TYPE_ARM_VGIC_V2,
+#define KVM_DEV_TYPE_ARM_VGIC_V2	KVM_DEV_TYPE_ARM_VGIC_V2
+	KVM_DEV_TYPE_FLIC,
+#define KVM_DEV_TYPE_FLIC		KVM_DEV_TYPE_FLIC
+	KVM_DEV_TYPE_MAX,
+};
 
 /*
  * ioctls for VM fds
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4b6c01b477f9..a8539ae10247 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2257,44 +2257,55 @@  struct kvm_device *kvm_device_from_filp(struct file *filp)
 	return filp->private_data;
 }
 
-static int kvm_ioctl_create_device(struct kvm *kvm,
-				   struct kvm_create_device *cd)
-{
-	struct kvm_device_ops *ops = NULL;
-	struct kvm_device *dev;
-	bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
-	int ret;
-
-	switch (cd->type) {
+static struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
 #ifdef CONFIG_KVM_MPIC
-	case KVM_DEV_TYPE_FSL_MPIC_20:
-	case KVM_DEV_TYPE_FSL_MPIC_42:
-		ops = &kvm_mpic_ops;
-		break;
+	[KVM_DEV_TYPE_FSL_MPIC_20]	= &kvm_mpic_ops,
+	[KVM_DEV_TYPE_FSL_MPIC_42]	= &kvm_mpic_ops,
 #endif
+
 #ifdef CONFIG_KVM_XICS
-	case KVM_DEV_TYPE_XICS:
-		ops = &kvm_xics_ops;
-		break;
+	[KVM_DEV_TYPE_XICS]		= &kvm_xics_ops,
 #endif
+
 #ifdef CONFIG_KVM_VFIO
-	case KVM_DEV_TYPE_VFIO:
-		ops = &kvm_vfio_ops;
-		break;
+	[KVM_DEV_TYPE_VFIO]		= &kvm_vfio_ops,
 #endif
+
 #ifdef CONFIG_KVM_ARM_VGIC
-	case KVM_DEV_TYPE_ARM_VGIC_V2:
-		ops = &kvm_arm_vgic_v2_ops;
-		break;
+	[KVM_DEV_TYPE_ARM_VGIC_V2]	= &kvm_arm_vgic_v2_ops,
 #endif
+
 #ifdef CONFIG_S390
-	case KVM_DEV_TYPE_FLIC:
-		ops = &kvm_flic_ops;
-		break;
+	[KVM_DEV_TYPE_FLIC]		= &kvm_flic_ops,
 #endif
-	default:
+};
+
+int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type)
+{
+	if (type >= ARRAY_SIZE(kvm_device_ops_table))
+		return -ENOSPC;
+
+	if (kvm_device_ops_table[type] != NULL)
+		return -EEXIST;
+
+	kvm_device_ops_table[type] = ops;
+	return 0;
+}
+
+static int kvm_ioctl_create_device(struct kvm *kvm,
+				   struct kvm_create_device *cd)
+{
+	struct kvm_device_ops *ops = NULL;
+	struct kvm_device *dev;
+	bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
+	int ret;
+
+	if (cd->type >= ARRAY_SIZE(kvm_device_ops_table))
+		return -ENODEV;
+
+	ops = kvm_device_ops_table[cd->type];
+	if (ops == NULL)
 		return -ENODEV;
-	}
 
 	if (test)
 		return 0;