kvm: add device control API

Currently, devices that are emulated inside KVM are configured in a
hardcoded manner based on an assumption that any given architecture
only has one way to do it.  If there's any need to access device state,
it is done through inflexible one-purpose-only IOCTLs (e.g.
KVM_GET/SET_LAPIC).  Defining new IOCTLs for every little thing is
cumbersome and depletes a limited numberspace.

This API provides a mechanism to instantiate a device of a certain
type, returning an ID that can be used to set/get attributes of the
device.  Attributes may include configuration parameters (e.g.
register base address), device state, operational commands, etc.  It
is similar to the ONE_REG API, except that it acts on devices rather
than vcpus.

Both device types and individual attributes can be tested without having
to create the device or get/set the attribute, without the need for
separately managing enumerated capabilities.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 27 insertions, 0 deletions

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index c741902c9e0b..38a0be0c199f 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -666,6 +666,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_PPC_EPR 86
 #define KVM_CAP_ARM_PSCI 87
 #define KVM_CAP_ARM_SET_DEVICE_ADDR 88
+#define KVM_CAP_DEVICE_CTRL 89
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -819,6 +820,24 @@ struct kvm_arm_device_addr {
 };
 
 /*
+ * Device control API, available with KVM_CAP_DEVICE_CTRL
+ */
+#define KVM_CREATE_DEVICE_TEST          1
+
+struct kvm_create_device {
+        __u32   type;   /* in: KVM_DEV_TYPE_xxx */
+        __u32   fd;     /* out: device handle */
+        __u32   flags;  /* in: KVM_CREATE_DEVICE_xxx */
+};
+
+struct kvm_device_attr {
+        __u32   flags;          /* no flags currently defined */
+        __u32   group;          /* device-defined */
+        __u64   attr;           /* group-defined */
+        __u64   addr;           /* userspace address of attr data */
+};
+
+/*
  * ioctls for VM fds
  */
 #define KVM_SET_MEMORY_REGION     _IOW(KVMIO,  0x40, struct kvm_memory_region)
@@ -906,6 +925,14 @@ struct kvm_s390_ucas_mapping {
 /* Available with KVM_CAP_ARM_SET_DEVICE_ADDR */
 #define KVM_ARM_SET_DEVICE_ADDR   _IOW(KVMIO,  0xab, struct kvm_arm_device_addr)
 
+/* ioctl for vm fd */
+#define KVM_CREATE_DEVICE         _IOWR(KVMIO,  0xe0, struct kvm_create_device)
+
+/* ioctls for fds returned by KVM_CREATE_DEVICE */
+#define KVM_SET_DEVICE_ATTR       _IOW(KVMIO,  0xe1, struct kvm_device_attr)
+#define KVM_GET_DEVICE_ATTR       _IOW(KVMIO,  0xe2, struct kvm_device_attr)
+#define KVM_HAS_DEVICE_ATTR       _IOW(KVMIO,  0xe3, struct kvm_device_attr)
+
 /*
  * ioctls for vcpu fds
  */