KVM: remove in_range from io devices

This changes bus accesses to use high-level kvm_io_bus_read/kvm_io_bus_write
functions. in_range now becomes unused so it is removed from device ops in
favor of read/write callbacks performing range checks internally.

This allows aliasing (mostly for in-kernel virtio), as well as better error
handling by making it possible to pass errors up to userspace.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 15 insertions, 24 deletions

diff --git a/virt/kvm/iodev.h b/virt/kvm/iodev.h
index 06e38b23fa61..12fd3caffd2b 100644
--- a/virt/kvm/iodev.h
+++ b/virt/kvm/iodev.h
@@ -17,23 +17,24 @@
 #define __KVM_IODEV_H__
 
 #include <linux/kvm_types.h>
+#include <asm/errno.h>
 
 struct kvm_io_device;
 
 /**
  * kvm_io_device_ops are called under kvm slots_lock.
+ * read and write handlers return 0 if the transaction has been handled,
+ * or non-zero to have it passed to the next device.
  **/
 struct kvm_io_device_ops {
-        void (*read)(struct kvm_io_device *this,
+        int (*read)(struct kvm_io_device *this,
+                    gpa_t addr,
+                    int len,
+                    void *val);
+        int (*write)(struct kvm_io_device *this,
                      gpa_t addr,
                      int len,
-                     void *val);
-        void (*write)(struct kvm_io_device *this,
-                      gpa_t addr,
-                      int len,
-                      const void *val);
-        int (*in_range)(struct kvm_io_device *this, gpa_t addr, int len,
-                        int is_write);
+                     const void *val);
         void (*destructor)(struct kvm_io_device *this);
 };
 
@@ -48,26 +49,16 @@ static inline void kvm_iodevice_init(struct kvm_io_device *dev,
         dev->ops = ops;
 }
 
-static inline void kvm_iodevice_read(struct kvm_io_device *dev,
-                                     gpa_t addr,
-                                     int len,
-                                     void *val)
+static inline int kvm_iodevice_read(struct kvm_io_device *dev,
+                                    gpa_t addr, int l, void *v)
 {
-        dev->ops->read(dev, addr, len, val);
+        return dev->ops->read ? dev->ops->read(dev, addr, l, v) : -EOPNOTSUPP;
 }
 
-static inline void kvm_iodevice_write(struct kvm_io_device *dev,
-                                      gpa_t addr,
-                                      int len,
-                                      const void *val)
+static inline int kvm_iodevice_write(struct kvm_io_device *dev,
+                                     gpa_t addr, int l, const void *v)
 {
-        dev->ops->write(dev, addr, len, val);
-}
-
-static inline int kvm_iodevice_in_range(struct kvm_io_device *dev,
-                                        gpa_t addr, int len, int is_write)
-{
-        return dev->ops->in_range(dev, addr, len, is_write);
+        return dev->ops->write ? dev->ops->write(dev, addr, l, v) : -EOPNOTSUPP;
 }
 
 static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)